** "experimental".  Experimental interfaces are normally new
** features recently added to SQLite.  We do not anticipate changes
** to experimental interfaces but reserve the right to make minor changes
** if experience from use "in the wild" suggest such changes are prudent.
**
** The official C-language API documentation for SQLite is derived
** from comments in this file.  This file is the authoritative source
** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
*/
#ifndef _SQLITE3_H_
................................................................................
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.8.11"
#define SQLITE_VERSION_NUMBER 3008011
#define SQLITE_SOURCE_ID      "2015-05-30 22:05:17 73fc058b3a74c1b018cff990de793f19a602c12f"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
#define OP_OpenWrite      55 /* synopsis: root=P2 iDb=P3                   */
#define OP_OpenAutoindex  56 /* synopsis: nColumn=P2                       */
#define OP_OpenEphemeral  57 /* synopsis: nColumn=P2                       */
#define OP_SorterOpen     58
#define OP_SequenceTest   59 /* synopsis: if( cursor[P1].ctr++ ) pc = P2   */
#define OP_OpenPseudo     60 /* synopsis: P3 columns in r[P2]              */
#define OP_Close          61

#define OP_SeekLT         62 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekLE         63 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekGE         64 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekGT         65 /* synopsis: key=r[P3@P4]                     */
#define OP_Seek           66 /* synopsis: intkey=r[P2]                     */
#define OP_NoConflict     67 /* synopsis: key=r[P3@P4]                     */
#define OP_NotFound       68 /* synopsis: key=r[P3@P4]                     */
#define OP_Found          69 /* synopsis: key=r[P3@P4]                     */
#define OP_NotExists      70 /* synopsis: intkey=r[P3]                     */
#define OP_Or             71 /* same as TK_OR, synopsis: r[P3]=(r[P1] || r[P2]) */
#define OP_And            72 /* same as TK_AND, synopsis: r[P3]=(r[P1] && r[P2]) */

#define OP_Sequence       73 /* synopsis: r[P2]=cursor[P1].ctr++           */
#define OP_NewRowid       74 /* synopsis: r[P2]=rowid                      */
#define OP_Insert         75 /* synopsis: intkey=r[P3] data=r[P2]          */
#define OP_IsNull         76 /* same as TK_ISNULL, synopsis: if r[P1]==NULL goto P2 */
#define OP_NotNull        77 /* same as TK_NOTNULL, synopsis: if r[P1]!=NULL goto P2 */
#define OP_Ne             78 /* same as TK_NE, synopsis: if r[P1]!=r[P3] goto P2 */
#define OP_Eq             79 /* same as TK_EQ, synopsis: if r[P1]==r[P3] goto P2 */
#define OP_Gt             80 /* same as TK_GT, synopsis: if r[P1]>r[P3] goto P2 */
#define OP_Le             81 /* same as TK_LE, synopsis: if r[P1]<=r[P3] goto P2 */
#define OP_Lt             82 /* same as TK_LT, synopsis: if r[P1]<r[P3] goto P2 */
#define OP_Ge             83 /* same as TK_GE, synopsis: if r[P1]>=r[P3] goto P2 */
#define OP_InsertInt      84 /* synopsis: intkey=P3 data=r[P2]             */
#define OP_BitAnd         85 /* same as TK_BITAND, synopsis: r[P3]=r[P1]&r[P2] */
#define OP_BitOr          86 /* same as TK_BITOR, synopsis: r[P3]=r[P1]|r[P2] */
#define OP_ShiftLeft      87 /* same as TK_LSHIFT, synopsis: r[P3]=r[P2]<<r[P1] */
#define OP_ShiftRight     88 /* same as TK_RSHIFT, synopsis: r[P3]=r[P2]>>r[P1] */
#define OP_Add            89 /* same as TK_PLUS, synopsis: r[P3]=r[P1]+r[P2] */
#define OP_Subtract       90 /* same as TK_MINUS, synopsis: r[P3]=r[P2]-r[P1] */
#define OP_Multiply       91 /* same as TK_STAR, synopsis: r[P3]=r[P1]*r[P2] */
#define OP_Divide         92 /* same as TK_SLASH, synopsis: r[P3]=r[P2]/r[P1] */
#define OP_Remainder      93 /* same as TK_REM, synopsis: r[P3]=r[P2]%r[P1] */
#define OP_Concat         94 /* same as TK_CONCAT, synopsis: r[P3]=r[P2]+r[P1] */
#define OP_Delete         95
#define OP_BitNot         96 /* same as TK_BITNOT, synopsis: r[P1]= ~r[P1] */
#define OP_String8        97 /* same as TK_STRING, synopsis: r[P2]='P4'    */

#define OP_ResetCount     98
#define OP_SorterCompare  99 /* synopsis: if key(P1)!=trim(r[P3],P4) goto P2 */
#define OP_SorterData    100 /* synopsis: r[P2]=data                       */
#define OP_RowKey        101 /* synopsis: r[P2]=key                        */
#define OP_RowData       102 /* synopsis: r[P2]=data                       */
#define OP_Rowid         103 /* synopsis: r[P2]=rowid                      */
#define OP_NullRow       104
#define OP_Last          105
#define OP_SorterSort    106
#define OP_Sort          107
#define OP_Rewind        108
#define OP_SorterInsert  109
#define OP_IdxInsert     110 /* synopsis: key=r[P2]                        */
#define OP_IdxDelete     111 /* synopsis: key=r[P2@P3]                     */
#define OP_IdxRowid      112 /* synopsis: r[P2]=rowid                      */
#define OP_IdxLE         113 /* synopsis: key=r[P3@P4]                     */
#define OP_IdxGT         114 /* synopsis: key=r[P3@P4]                     */
#define OP_IdxLT         115 /* synopsis: key=r[P3@P4]                     */
#define OP_IdxGE         116 /* synopsis: key=r[P3@P4]                     */
#define OP_Destroy       117
#define OP_Clear         118
#define OP_ResetSorter   119
#define OP_CreateIndex   120 /* synopsis: r[P2]=root iDb=P1                */
#define OP_CreateTable   121 /* synopsis: r[P2]=root iDb=P1                */
#define OP_ParseSchema   122
#define OP_LoadAnalysis  123
#define OP_DropTable     124
#define OP_DropIndex     125
#define OP_DropTrigger   126
#define OP_IntegrityCk   127
#define OP_RowSetAdd     128 /* synopsis: rowset(P1)=r[P2]                 */
#define OP_RowSetRead    129 /* synopsis: r[P3]=rowset(P1)                 */
#define OP_RowSetTest    130 /* synopsis: if r[P3] in rowset(P1) goto P2   */
#define OP_Program       131
#define OP_Param         132
#define OP_Real          133 /* same as TK_FLOAT, synopsis: r[P2]=P4       */

#define OP_FkCounter     134 /* synopsis: fkctr[P1]+=P2                    */
#define OP_FkIfZero      135 /* synopsis: if fkctr[P1]==0 goto P2          */
#define OP_MemMax        136 /* synopsis: r[P1]=max(r[P1],r[P2])           */
#define OP_IfPos         137 /* synopsis: if r[P1]>0 goto P2               */
#define OP_IfNeg         138 /* synopsis: r[P1]+=P3, if r[P1]<0 goto P2    */
#define OP_IfNotZero     139 /* synopsis: if r[P1]!=0 then r[P1]+=P3, goto P2 */
#define OP_DecrJumpZero  140 /* synopsis: if (--r[P1])==0 goto P2          */
#define OP_JumpZeroIncr  141 /* synopsis: if (r[P1]++)==0 ) goto P2        */
#define OP_AggFinal      142 /* synopsis: accum=r[P1] N=P2                 */
#define OP_IncrVacuum    143
#define OP_Expire        144
#define OP_TableLock     145 /* synopsis: iDb=P1 root=P2 write=P3          */
#define OP_VBegin        146
#define OP_VCreate       147
#define OP_VDestroy      148
#define OP_VOpen         149
#define OP_VColumn       150 /* synopsis: r[P3]=vcolumn(P2)                */
#define OP_VNext         151
#define OP_VRename       152
#define OP_Pagecount     153
#define OP_MaxPgcnt      154
#define OP_Init          155 /* synopsis: Start at P2                      */
#define OP_Noop          156
#define OP_Explain       157


/* Properties such as "out2" or "jump" that are specified in
** comments following the "case" for each opcode in the vdbe.c
** are encoded into bitvectors as follows:
*/
#define OPFLG_JUMP            0x0001  /* jump:  P2 holds jmp target */
................................................................................
/*   0 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01,\
/*   8 */ 0x01, 0x01, 0x00, 0x00, 0x10, 0x00, 0x01, 0x00,\
/*  16 */ 0x01, 0x01, 0x02, 0x12, 0x01, 0x02, 0x03, 0x08,\
/*  24 */ 0x00, 0x10, 0x10, 0x10, 0x10, 0x00, 0x10, 0x10,\
/*  32 */ 0x00, 0x00, 0x10, 0x00, 0x00, 0x02, 0x03, 0x02,\
/*  40 */ 0x02, 0x00, 0x00, 0x01, 0x01, 0x03, 0x03, 0x00,\
/*  48 */ 0x00, 0x00, 0x10, 0x10, 0x08, 0x00, 0x00, 0x00,\
/*  56 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x09, 0x09,\
/*  64 */ 0x09, 0x09, 0x04, 0x09, 0x09, 0x09, 0x09, 0x26,\
/*  72 */ 0x26, 0x10, 0x10, 0x00, 0x03, 0x03, 0x0b, 0x0b,\
/*  80 */ 0x0b, 0x0b, 0x0b, 0x0b, 0x00, 0x26, 0x26, 0x26,\
/*  88 */ 0x26, 0x26, 0x26, 0x26, 0x26, 0x26, 0x26, 0x00,\
/*  96 */ 0x12, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,\
/* 104 */ 0x00, 0x01, 0x01, 0x01, 0x01, 0x04, 0x04, 0x00,\
/* 112 */ 0x10, 0x01, 0x01, 0x01, 0x01, 0x10, 0x00, 0x00,\
/* 120 */ 0x10, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
/* 128 */ 0x06, 0x23, 0x0b, 0x01, 0x10, 0x10, 0x00, 0x01,\
/* 136 */ 0x04, 0x03, 0x03, 0x03, 0x03, 0x03, 0x00, 0x01,\
/* 144 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,\
/* 152 */ 0x00, 0x10, 0x10, 0x01, 0x00, 0x00,}

/************** End of opcodes.h *********************************************/
/************** Continuing where we left off in vdbe.h ***********************/

/*
** Prototypes for the VDBE interface.  See comments on the implementation
** for a description of what each of these routines does.
................................................................................
*/
SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(Parse*);
SQLITE_PRIVATE int sqlite3VdbeAddOp0(Vdbe*,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp1(Vdbe*,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp2(Vdbe*,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp3(Vdbe*,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4(Vdbe*,int,int,int,int,const char *zP4,int);

SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(Vdbe*,int,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp, int iLineno);
SQLITE_PRIVATE void sqlite3VdbeAddParseSchemaOp(Vdbe*,int,char*);
SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe*, u32 addr, int P1);
SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe*, u32 addr, int P2);
SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe*, u32 addr, int P3);
SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe*, u8 P5);
................................................................................
** the speed a little by numbering the values consecutively.  
**
** But rather than start with 0 or 1, we begin with 'A'.  That way,
** when multiple affinity types are concatenated into a string and
** used as the P4 operand, they will be more readable.
**
** Note also that the numeric types are grouped together so that testing
** for a numeric type is a single comparison.  And the NONE type is first.
*/
#define SQLITE_AFF_NONE     'A'
#define SQLITE_AFF_TEXT     'B'
#define SQLITE_AFF_NUMERIC  'C'
#define SQLITE_AFF_INTEGER  'D'
#define SQLITE_AFF_REAL     'E'

#define sqlite3IsNumericAffinity(X)  ((X)>=SQLITE_AFF_NUMERIC)

................................................................................
#ifndef SQLITE_OMIT_EXPLAIN
    u8 iSelectId;     /* If pSelect!=0, the id of the sub-select in EQP */
#endif
    int iCursor;      /* The VDBE cursor number used to access this table */
    Expr *pOn;        /* The ON clause of a join */
    IdList *pUsing;   /* The USING clause of a join */
    Bitmask colUsed;  /* Bit N (1<<N) set if column N of pTab is used */
    char *zIndex;     /* Identifier from "INDEXED BY <zIndex>" clause */
    Index *pIndex;    /* Index structure corresponding to zIndex, if any */
  } a[1];             /* One entry for each identifier on the list */
};

/*
** Permitted values of the SrcList.a.jointype field
*/
................................................................................
# define sqlite3Isspace(x)   isspace((unsigned char)(x))
# define sqlite3Isalnum(x)   isalnum((unsigned char)(x))
# define sqlite3Isalpha(x)   isalpha((unsigned char)(x))
# define sqlite3Isdigit(x)   isdigit((unsigned char)(x))
# define sqlite3Isxdigit(x)  isxdigit((unsigned char)(x))
# define sqlite3Tolower(x)   tolower((unsigned char)(x))
#endif

SQLITE_PRIVATE int sqlite3IsIdChar(u8);


/*
** Internal function prototypes
*/
#define sqlite3StrICmp sqlite3_stricmp
SQLITE_PRIVATE int sqlite3Strlen30(const char*);
#define sqlite3StrNICmp sqlite3_strnicmp
................................................................................
SQLITE_PRIVATE int sqlite3MallocSize(void*);
SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3*, void*);
SQLITE_PRIVATE void *sqlite3ScratchMalloc(int);
SQLITE_PRIVATE void sqlite3ScratchFree(void*);
SQLITE_PRIVATE void *sqlite3PageMalloc(int);
SQLITE_PRIVATE void sqlite3PageFree(void*);
SQLITE_PRIVATE void sqlite3MemSetDefault(void);

SQLITE_PRIVATE void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));

SQLITE_PRIVATE int sqlite3HeapNearlyFull(void);

/*
** On systems with ample stack space and that support alloca(), make
** use of alloca() to obtain space for large automatic objects.  By default,
** obtain space from malloc().
**
................................................................................
SQLITE_PRIVATE   void sqlite3DebugPrintf(const char*, ...);
#endif
#if defined(SQLITE_TEST)
SQLITE_PRIVATE   void *sqlite3TestTextToPtr(const char*);
#endif

#if defined(SQLITE_DEBUG)
SQLITE_PRIVATE   TreeView *sqlite3TreeViewPush(TreeView*,u8);
SQLITE_PRIVATE   void sqlite3TreeViewPop(TreeView*);
SQLITE_PRIVATE   void sqlite3TreeViewLine(TreeView*, const char*, ...);
SQLITE_PRIVATE   void sqlite3TreeViewItem(TreeView*, const char*, u8);
SQLITE_PRIVATE   void sqlite3TreeViewExpr(TreeView*, const Expr*, u8);
SQLITE_PRIVATE   void sqlite3TreeViewExprList(TreeView*, const ExprList*, u8, const char*);
SQLITE_PRIVATE   void sqlite3TreeViewSelect(TreeView*, const Select*, u8);
#endif


SQLITE_PRIVATE void sqlite3SetString(char **, sqlite3*, const char*);
................................................................................

SQLITE_PRIVATE Bitvec *sqlite3BitvecCreate(u32);
SQLITE_PRIVATE int sqlite3BitvecTest(Bitvec*, u32);
SQLITE_PRIVATE int sqlite3BitvecSet(Bitvec*, u32);
SQLITE_PRIVATE void sqlite3BitvecClear(Bitvec*, u32, void*);
SQLITE_PRIVATE void sqlite3BitvecDestroy(Bitvec*);
SQLITE_PRIVATE u32 sqlite3BitvecSize(Bitvec*);

SQLITE_PRIVATE int sqlite3BitvecBuiltinTest(int,int*);


SQLITE_PRIVATE RowSet *sqlite3RowSetInit(sqlite3*, void*, unsigned int);
SQLITE_PRIVATE void sqlite3RowSetClear(RowSet*);
SQLITE_PRIVATE void sqlite3RowSetInsert(RowSet*, i64);
SQLITE_PRIVATE int sqlite3RowSetTest(RowSet*, int iBatch, i64);
SQLITE_PRIVATE int sqlite3RowSetNext(RowSet*, i64*);

................................................................................
SQLITE_PRIVATE int sqlite3ExprCodeTarget(Parse*, Expr*, int);
SQLITE_PRIVATE void sqlite3ExprCodeAndCache(Parse*, Expr*, int);
SQLITE_PRIVATE int sqlite3ExprCodeExprList(Parse*, ExprList*, int, u8);
#define SQLITE_ECEL_DUP      0x01  /* Deep, not shallow copies */
#define SQLITE_ECEL_FACTOR   0x02  /* Factor out constant terms */
SQLITE_PRIVATE void sqlite3ExprIfTrue(Parse*, Expr*, int, int);
SQLITE_PRIVATE void sqlite3ExprIfFalse(Parse*, Expr*, int, int);

SQLITE_PRIVATE Table *sqlite3FindTable(sqlite3*,const char*, const char*);
SQLITE_PRIVATE Table *sqlite3LocateTable(Parse*,int isView,const char*, const char*);
SQLITE_PRIVATE Table *sqlite3LocateTableItem(Parse*,int isView,struct SrcList_item *);
SQLITE_PRIVATE Index *sqlite3FindIndex(sqlite3*,const char*, const char*);
SQLITE_PRIVATE void sqlite3UnlinkAndDeleteTable(sqlite3*,int,const char*);
SQLITE_PRIVATE void sqlite3UnlinkAndDeleteIndex(sqlite3*,int,const char*);
SQLITE_PRIVATE void sqlite3Vacuum(Parse*);
................................................................................
SQLITE_PRIVATE int sqlite3ExprCompare(Expr*, Expr*, int);
SQLITE_PRIVATE int sqlite3ExprListCompare(ExprList*, ExprList*, int);
SQLITE_PRIVATE int sqlite3ExprImpliesExpr(Expr*, Expr*, int);
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
SQLITE_PRIVATE int sqlite3FunctionUsesThisSrc(Expr*, SrcList*);
SQLITE_PRIVATE Vdbe *sqlite3GetVdbe(Parse*);

SQLITE_PRIVATE void sqlite3PrngSaveState(void);
SQLITE_PRIVATE void sqlite3PrngRestoreState(void);

SQLITE_PRIVATE void sqlite3RollbackAll(sqlite3*,int);
SQLITE_PRIVATE void sqlite3CodeVerifySchema(Parse*, int);
SQLITE_PRIVATE void sqlite3CodeVerifyNamedSchema(Parse*, const char *zDb);
SQLITE_PRIVATE void sqlite3BeginTransaction(Parse*, int);
SQLITE_PRIVATE void sqlite3CommitTransaction(Parse*);
SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse*);
SQLITE_PRIVATE void sqlite3Savepoint(Parse*, int, Token*);
................................................................................
SQLITE_PRIVATE void sqlite3AlterFunctions(void);
SQLITE_PRIVATE void sqlite3AlterRenameTable(Parse*, SrcList*, Token*);
SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *, int *);
SQLITE_PRIVATE void sqlite3NestedParse(Parse*, const char*, ...);
SQLITE_PRIVATE void sqlite3ExpirePreparedStatements(sqlite3*);
SQLITE_PRIVATE int sqlite3CodeSubselect(Parse *, Expr *, int, int);
SQLITE_PRIVATE void sqlite3SelectPrep(Parse*, Select*, NameContext*);

SQLITE_PRIVATE int sqlite3MatchSpanName(const char*, const char*, const char*, const char*);
SQLITE_PRIVATE int sqlite3ResolveExprNames(NameContext*, Expr*);
SQLITE_PRIVATE void sqlite3ResolveSelectNames(Parse*, Select*, NameContext*);
SQLITE_PRIVATE void sqlite3ResolveSelfReference(Parse*,Table*,int,Expr*,ExprList*);
SQLITE_PRIVATE int sqlite3ResolveOrderGroupBy(Parse*, Select*, ExprList*, const char*);
SQLITE_PRIVATE void sqlite3ColumnDefault(Vdbe *, Table *, int, int);
SQLITE_PRIVATE void sqlite3AlterFinishAddColumn(Parse *, Token *);
................................................................................
  Bool isTable:1;       /* True if a table requiring integer keys */
  Bool isOrdered:1;     /* True if the underlying table is BTREE_UNORDERED */
  Pgno pgnoRoot;        /* Root page of the open btree cursor */
  sqlite3_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
  i64 seqCount;         /* Sequence counter */
  i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
  VdbeSorter *pSorter;  /* Sorter object for OP_SorterOpen cursors */




  /* Cached information about the header for the data record that the
  ** cursor is currently pointing to.  Only valid if cacheStatus matches
  ** Vdbe.cacheCtr.  Vdbe.cacheCtr will never take on the value of
  ** CACHE_STALE and so setting cacheStatus=CACHE_STALE guarantees that
  ** the cache is out of date.
  **
................................................................................
    sqlite3_mutex_methods *pTo = &sqlite3GlobalConfig.mutex;

    if( sqlite3GlobalConfig.bCoreMutex ){
      pFrom = sqlite3DefaultMutex();
    }else{
      pFrom = sqlite3NoopMutex();
    }
    memcpy(pTo, pFrom, offsetof(sqlite3_mutex_methods, xMutexAlloc));
    memcpy(&pTo->xMutexFree, &pFrom->xMutexFree,
           sizeof(*pTo) - offsetof(sqlite3_mutex_methods, xMutexFree));





    pTo->xMutexAlloc = pFrom->xMutexAlloc;
  }
  rc = sqlite3GlobalConfig.mutex.xMutexInit();

#ifdef SQLITE_DEBUG
  GLOBAL(int, mutexIsInit) = 1;
#endif
................................................................................
  return rc & db->errMask;
}

/************** End of malloc.c **********************************************/
/************** Begin file printf.c ******************************************/
/*
** The "printf" code that follows dates from the 1980's.  It is in
** the public domain.  The original comments are included here for
** completeness.  They are very out-of-date but might be useful as
** an historical reference.  Most of the "enhancements" have been backed
** out so that the functionality is now the same as standard printf().
**
**************************************************************************
**
** This file contains code for a set of "printf"-like routines.  These
** routines format strings much like the printf() from the standard C
** library, though the implementation here has enhancements to support
** SQLlite.
*/

/*
** Conversion types fall into various categories as defined by the
** following enumeration.
*/
#define etRADIX       1 /* Integer types.  %d, %x, %o, and so forth */
................................................................................
  va_end(ap);
  sqlite3StrAccumFinish(&acc);
  fprintf(stdout,"%s", zBuf);
  fflush(stdout);
}
#endif

#ifdef SQLITE_DEBUG























/*************************************************************************
** Routines for implementing the "TreeView" display of hierarchical
** data structures for debugging.
**
** The main entry points (coded elsewhere) are:
**     sqlite3TreeViewExpr(0, pExpr, 0);
**     sqlite3TreeViewExprList(0, pList, 0, 0);
**     sqlite3TreeViewSelect(0, pSelect, 0);
** Insert calls to those routines while debugging in order to display
** a diagram of Expr, ExprList, and Select objects.



**


*/



/* Add a new subitem to the tree.  The moreToFollow flag indicates that this
** is not the last item in the tree. */

SQLITE_PRIVATE TreeView *sqlite3TreeViewPush(TreeView *p, u8 moreToFollow){
  if( p==0 ){
    p = sqlite3_malloc64( sizeof(*p) );
    if( p==0 ) return 0;
    memset(p, 0, sizeof(*p));
  }else{
    p->iLevel++;
  }
  assert( moreToFollow==0 || moreToFollow==1 );
  if( p->iLevel<sizeof(p->bLine) ) p->bLine[p->iLevel] = moreToFollow;
  return p;
}


/* Finished with one layer of the tree */

SQLITE_PRIVATE void sqlite3TreeViewPop(TreeView *p){
  if( p==0 ) return;
  p->iLevel--;
  if( p->iLevel<0 ) sqlite3_free(p);
}


/* Generate a single line of output for the tree, with a prefix that contains
** all the appropriate tree lines */

SQLITE_PRIVATE void sqlite3TreeViewLine(TreeView *p, const char *zFormat, ...){
  va_list ap;
  int i;
  StrAccum acc;
  char zBuf[500];
  sqlite3StrAccumInit(&acc, 0, zBuf, sizeof(zBuf), 0);
  if( p ){
    for(i=0; i<p->iLevel && i<sizeof(p->bLine)-1; i++){
................................................................................
  sqlite3VXPrintf(&acc, 0, zFormat, ap);
  va_end(ap);
  if( zBuf[acc.nChar-1]!='\n' ) sqlite3StrAccumAppend(&acc, "\n", 1);
  sqlite3StrAccumFinish(&acc);
  fprintf(stdout,"%s", zBuf);
  fflush(stdout);
}


/* Shorthand for starting a new tree item that consists of a single label */

SQLITE_PRIVATE void sqlite3TreeViewItem(TreeView *p, const char *zLabel, u8 moreToFollow){
  p = sqlite3TreeViewPush(p, moreToFollow);
  sqlite3TreeViewLine(p, "%s", zLabel);
}





















































































































































































#endif /* SQLITE_DEBUG */













































































/*
** variable-argument wrapper around sqlite3VXPrintf().









*/




























































SQLITE_PRIVATE void sqlite3XPrintf(StrAccum *p, u32 bFlags, const char *zFormat, ...){
  va_list ap;
  va_start(ap,zFormat);
  sqlite3VXPrintf(p, bFlags, zFormat, ap);
  va_end(ap);














}






/************** End of printf.c **********************************************/
/************** Begin file random.c ******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
................................................................................
     /*  55 */ "OpenWrite"        OpHelp("root=P2 iDb=P3"),
     /*  56 */ "OpenAutoindex"    OpHelp("nColumn=P2"),
     /*  57 */ "OpenEphemeral"    OpHelp("nColumn=P2"),
     /*  58 */ "SorterOpen"       OpHelp(""),
     /*  59 */ "SequenceTest"     OpHelp("if( cursor[P1].ctr++ ) pc = P2"),
     /*  60 */ "OpenPseudo"       OpHelp("P3 columns in r[P2]"),
     /*  61 */ "Close"            OpHelp(""),

     /*  62 */ "SeekLT"           OpHelp("key=r[P3@P4]"),
     /*  63 */ "SeekLE"           OpHelp("key=r[P3@P4]"),
     /*  64 */ "SeekGE"           OpHelp("key=r[P3@P4]"),
     /*  65 */ "SeekGT"           OpHelp("key=r[P3@P4]"),
     /*  66 */ "Seek"             OpHelp("intkey=r[P2]"),
     /*  67 */ "NoConflict"       OpHelp("key=r[P3@P4]"),
     /*  68 */ "NotFound"         OpHelp("key=r[P3@P4]"),
     /*  69 */ "Found"            OpHelp("key=r[P3@P4]"),
     /*  70 */ "NotExists"        OpHelp("intkey=r[P3]"),
     /*  71 */ "Or"               OpHelp("r[P3]=(r[P1] || r[P2])"),
     /*  72 */ "And"              OpHelp("r[P3]=(r[P1] && r[P2])"),

     /*  73 */ "Sequence"         OpHelp("r[P2]=cursor[P1].ctr++"),
     /*  74 */ "NewRowid"         OpHelp("r[P2]=rowid"),
     /*  75 */ "Insert"           OpHelp("intkey=r[P3] data=r[P2]"),
     /*  76 */ "IsNull"           OpHelp("if r[P1]==NULL goto P2"),
     /*  77 */ "NotNull"          OpHelp("if r[P1]!=NULL goto P2"),
     /*  78 */ "Ne"               OpHelp("if r[P1]!=r[P3] goto P2"),
     /*  79 */ "Eq"               OpHelp("if r[P1]==r[P3] goto P2"),
     /*  80 */ "Gt"               OpHelp("if r[P1]>r[P3] goto P2"),
     /*  81 */ "Le"               OpHelp("if r[P1]<=r[P3] goto P2"),
     /*  82 */ "Lt"               OpHelp("if r[P1]<r[P3] goto P2"),
     /*  83 */ "Ge"               OpHelp("if r[P1]>=r[P3] goto P2"),
     /*  84 */ "InsertInt"        OpHelp("intkey=P3 data=r[P2]"),
     /*  85 */ "BitAnd"           OpHelp("r[P3]=r[P1]&r[P2]"),
     /*  86 */ "BitOr"            OpHelp("r[P3]=r[P1]|r[P2]"),
     /*  87 */ "ShiftLeft"        OpHelp("r[P3]=r[P2]<<r[P1]"),
     /*  88 */ "ShiftRight"       OpHelp("r[P3]=r[P2]>>r[P1]"),
     /*  89 */ "Add"              OpHelp("r[P3]=r[P1]+r[P2]"),
     /*  90 */ "Subtract"         OpHelp("r[P3]=r[P2]-r[P1]"),
     /*  91 */ "Multiply"         OpHelp("r[P3]=r[P1]*r[P2]"),
     /*  92 */ "Divide"           OpHelp("r[P3]=r[P2]/r[P1]"),
     /*  93 */ "Remainder"        OpHelp("r[P3]=r[P2]%r[P1]"),
     /*  94 */ "Concat"           OpHelp("r[P3]=r[P2]+r[P1]"),
     /*  95 */ "Delete"           OpHelp(""),
     /*  96 */ "BitNot"           OpHelp("r[P1]= ~r[P1]"),
     /*  97 */ "String8"          OpHelp("r[P2]='P4'"),

     /*  98 */ "ResetCount"       OpHelp(""),
     /*  99 */ "SorterCompare"    OpHelp("if key(P1)!=trim(r[P3],P4) goto P2"),
     /* 100 */ "SorterData"       OpHelp("r[P2]=data"),
     /* 101 */ "RowKey"           OpHelp("r[P2]=key"),
     /* 102 */ "RowData"          OpHelp("r[P2]=data"),
     /* 103 */ "Rowid"            OpHelp("r[P2]=rowid"),
     /* 104 */ "NullRow"          OpHelp(""),
     /* 105 */ "Last"             OpHelp(""),
     /* 106 */ "SorterSort"       OpHelp(""),
     /* 107 */ "Sort"             OpHelp(""),
     /* 108 */ "Rewind"           OpHelp(""),
     /* 109 */ "SorterInsert"     OpHelp(""),
     /* 110 */ "IdxInsert"        OpHelp("key=r[P2]"),
     /* 111 */ "IdxDelete"        OpHelp("key=r[P2@P3]"),
     /* 112 */ "IdxRowid"         OpHelp("r[P2]=rowid"),
     /* 113 */ "IdxLE"            OpHelp("key=r[P3@P4]"),
     /* 114 */ "IdxGT"            OpHelp("key=r[P3@P4]"),
     /* 115 */ "IdxLT"            OpHelp("key=r[P3@P4]"),
     /* 116 */ "IdxGE"            OpHelp("key=r[P3@P4]"),
     /* 117 */ "Destroy"          OpHelp(""),
     /* 118 */ "Clear"            OpHelp(""),
     /* 119 */ "ResetSorter"      OpHelp(""),
     /* 120 */ "CreateIndex"      OpHelp("r[P2]=root iDb=P1"),
     /* 121 */ "CreateTable"      OpHelp("r[P2]=root iDb=P1"),
     /* 122 */ "ParseSchema"      OpHelp(""),
     /* 123 */ "LoadAnalysis"     OpHelp(""),
     /* 124 */ "DropTable"        OpHelp(""),
     /* 125 */ "DropIndex"        OpHelp(""),
     /* 126 */ "DropTrigger"      OpHelp(""),
     /* 127 */ "IntegrityCk"      OpHelp(""),
     /* 128 */ "RowSetAdd"        OpHelp("rowset(P1)=r[P2]"),
     /* 129 */ "RowSetRead"       OpHelp("r[P3]=rowset(P1)"),
     /* 130 */ "RowSetTest"       OpHelp("if r[P3] in rowset(P1) goto P2"),
     /* 131 */ "Program"          OpHelp(""),
     /* 132 */ "Param"            OpHelp(""),
     /* 133 */ "Real"             OpHelp("r[P2]=P4"),

     /* 134 */ "FkCounter"        OpHelp("fkctr[P1]+=P2"),
     /* 135 */ "FkIfZero"         OpHelp("if fkctr[P1]==0 goto P2"),
     /* 136 */ "MemMax"           OpHelp("r[P1]=max(r[P1],r[P2])"),
     /* 137 */ "IfPos"            OpHelp("if r[P1]>0 goto P2"),
     /* 138 */ "IfNeg"            OpHelp("r[P1]+=P3, if r[P1]<0 goto P2"),
     /* 139 */ "IfNotZero"        OpHelp("if r[P1]!=0 then r[P1]+=P3, goto P2"),
     /* 140 */ "DecrJumpZero"     OpHelp("if (--r[P1])==0 goto P2"),
     /* 141 */ "JumpZeroIncr"     OpHelp("if (r[P1]++)==0 ) goto P2"),
     /* 142 */ "AggFinal"         OpHelp("accum=r[P1] N=P2"),
     /* 143 */ "IncrVacuum"       OpHelp(""),
     /* 144 */ "Expire"           OpHelp(""),
     /* 145 */ "TableLock"        OpHelp("iDb=P1 root=P2 write=P3"),
     /* 146 */ "VBegin"           OpHelp(""),
     /* 147 */ "VCreate"          OpHelp(""),
     /* 148 */ "VDestroy"         OpHelp(""),
     /* 149 */ "VOpen"            OpHelp(""),
     /* 150 */ "VColumn"          OpHelp("r[P3]=vcolumn(P2)"),
     /* 151 */ "VNext"            OpHelp(""),
     /* 152 */ "VRename"          OpHelp(""),
     /* 153 */ "Pagecount"        OpHelp(""),
     /* 154 */ "MaxPgcnt"         OpHelp(""),
     /* 155 */ "Init"             OpHelp("Start at P2"),
     /* 156 */ "Noop"             OpHelp(""),
     /* 157 */ "Explain"          OpHelp(""),
  };
  return azName[i];
}
#endif

/************** End of opcodes.c *********************************************/
/************** Begin file os_unix.c *****************************************/
................................................................................
  int szPage;                         /* Size of every page in this cache */
  int szExtra;                        /* Size of extra space for each page */
  u8 bPurgeable;                      /* True if pages are on backing store */
  u8 eCreate;                         /* eCreate value for for xFetch() */
  int (*xStress)(void*,PgHdr*);       /* Call to try make a page clean */
  void *pStress;                      /* Argument to xStress */
  sqlite3_pcache *pCache;             /* Pluggable cache module */
  PgHdr *pPage1;                      /* Reference to page 1 */
};

/********************************** Linked List Management ********************/

/* Allowed values for second argument to pcacheManageDirtyList() */
#define PCACHE_DIRTYLIST_REMOVE   1    /* Remove pPage from dirty list */
#define PCACHE_DIRTYLIST_ADD      2    /* Add pPage to the dirty list */
................................................................................

/*
** Wrapper around the pluggable caches xUnpin method. If the cache is
** being used for an in-memory database, this function is a no-op.
*/
static void pcacheUnpin(PgHdr *p){
  if( p->pCache->bPurgeable ){
    if( p->pgno==1 ){
      p->pCache->pPage1 = 0;
    }
    sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 0);
  }
}

/*
** Compute the number of pages of cache requested.  p->szCache is the
** cache size requested by the "PRAGMA cache_size" statement.
................................................................................
    );
    if( pNew==0 ) return SQLITE_NOMEM;
    sqlite3GlobalConfig.pcache2.xCachesize(pNew, numberOfCachePages(pCache));
    if( pCache->pCache ){
      sqlite3GlobalConfig.pcache2.xDestroy(pCache->pCache);
    }
    pCache->pCache = pNew;
    pCache->pPage1 = 0;
    pCache->szPage = szPage;
  }
  return SQLITE_OK;
}

/*
** Try to obtain a page from the cache.
................................................................................
  if( !pPgHdr->pPage ){
    return pcacheFetchFinishWithInit(pCache, pgno, pPage);
  }
  if( 0==pPgHdr->nRef ){
    pCache->nRef++;
  }
  pPgHdr->nRef++;
  if( pgno==1 ){
    pCache->pPage1 = pPgHdr;
  }
  return pPgHdr;
}

/*
** Decrement the reference count on a page. If the page is clean and the
** reference count drops to 0, then it is made eligible for recycling.
*/
................................................................................
*/
SQLITE_PRIVATE void sqlite3PcacheDrop(PgHdr *p){
  assert( p->nRef==1 );
  if( p->flags&PGHDR_DIRTY ){
    pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE);
  }
  p->pCache->nRef--;
  if( p->pgno==1 ){
    p->pCache->pPage1 = 0;
  }
  sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 1);
}

/*
** Make sure the page is marked as dirty. If it isn't dirty already,
** make it so.
*/
................................................................................
      */
      assert( p->pgno>0 );
      if( ALWAYS(p->pgno>pgno) ){
        assert( p->flags&PGHDR_DIRTY );
        sqlite3PcacheMakeClean(p);
      }
    }
    if( pgno==0 && pCache->pPage1 ){




      memset(pCache->pPage1->pData, 0, pCache->szPage);
      pgno = 1;

    }
    sqlite3GlobalConfig.pcache2.xTruncate(pCache->pCache, pgno+1);
  }
}

/*
** Close a cache.
................................................................................
** compiling for systems that do not support real WSD.
*/
#define pcache1 (GLOBAL(struct PCacheGlobal, pcache1_g))

/*
** Macros to enter and leave the PCache LRU mutex.
*/





#define pcache1EnterMutex(X) sqlite3_mutex_enter((X)->mutex)
#define pcache1LeaveMutex(X) sqlite3_mutex_leave((X)->mutex)



/******************************************************************************/
/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/

/*
** This function is called during initialization if a static buffer is 
** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE
................................................................................
/*
** This function is used internally to remove the page pPage from the 
** PGroup LRU list, if is part of it. If pPage is not part of the PGroup
** LRU list, then this function is a no-op.
**
** The PGroup mutex must be held when this function is called.
*/
static void pcache1PinPage(PgHdr1 *pPage){
  PCache1 *pCache;
  PGroup *pGroup;

  assert( pPage!=0 );
  assert( pPage->isPinned==0 );
  pCache = pPage->pCache;
  pGroup = pCache->pGroup;
  assert( pPage->pLruNext || pPage==pGroup->pLruTail );
  assert( pPage->pLruPrev || pPage==pGroup->pLruHead );
  assert( sqlite3_mutex_held(pGroup->mutex) );
  if( pPage->pLruPrev ){
    pPage->pLruPrev->pLruNext = pPage->pLruNext;
  }else{
    pGroup->pLruHead = pPage->pLruNext;
  }
  if( pPage->pLruNext ){
    pPage->pLruNext->pLruPrev = pPage->pLruPrev;
  }else{
    pGroup->pLruTail = pPage->pLruPrev;
  }
  pPage->pLruNext = 0;
  pPage->pLruPrev = 0;
  pPage->isPinned = 1;
  pCache->nRecyclable--;

}


/*
** Remove the page supplied as an argument from the hash table 
** (PCache1.apHash structure) that it is currently stored in.
**
................................................................................
/*
** Implementation of the sqlite3_pcache.xInit method.
*/
static int pcache1Init(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  assert( pcache1.isInit==0 );
  memset(&pcache1, 0, sizeof(pcache1));

  if( sqlite3GlobalConfig.bCoreMutex ){
    pcache1.grp.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PMEM);
  }

  pcache1.grp.mxPinned = 10;
  pcache1.isInit = 1;
  return SQLITE_OK;
}

/*
** Implementation of the sqlite3_pcache.xShutdown method.
................................................................................
    }
  }

  /* Step 5. If a usable page buffer has still not been found, 
  ** attempt to allocate a new one. 
  */
  if( !pPage ){
    if( createFlag==1 ) sqlite3BeginBenignMalloc();
    pPage = pcache1AllocPage(pCache);
    if( createFlag==1 ) sqlite3EndBenignMalloc();
  }

  if( pPage ){
    unsigned int h = iKey % pCache->nHash;
    pCache->nPage++;
    pPage->iKey = iKey;
    pPage->pNext = pCache->apHash[h];
................................................................................
**           unnecessary pages cache entry allocations
**
**      then attempt to recycle a page from the LRU list. If it is the right
**      size, return the recycled buffer. Otherwise, free the buffer and
**      proceed to step 5. 
**
**   5. Otherwise, allocate and return a new page buffer.





*/
static sqlite3_pcache_page *pcache1Fetch(

  sqlite3_pcache *p, 
  unsigned int iKey, 
  int createFlag
){
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = 0;

  assert( offsetof(PgHdr1,page)==0 );
  assert( pCache->bPurgeable || createFlag!=1 );
  assert( pCache->bPurgeable || pCache->nMin==0 );
  assert( pCache->bPurgeable==0 || pCache->nMin==10 );
  assert( pCache->nMin==0 || pCache->bPurgeable );
  assert( pCache->nHash>0 );
  pcache1EnterMutex(pCache->pGroup);

  /* Step 1: Search the hash table for an existing entry. */
  pPage = pCache->apHash[iKey % pCache->nHash];
  while( pPage && pPage->iKey!=iKey ){ pPage = pPage->pNext; }

  /* Step 2: Abort if no existing page is found and createFlag is 0 */
  if( pPage ){
    if( !pPage->isPinned ) pcache1PinPage(pPage);




  }else if( createFlag ){
    /* Steps 3, 4, and 5 implemented by this subroutine */
    pPage = pcache1FetchStage2(pCache, iKey, createFlag);


  }












  assert( pPage==0 || pCache->iMaxKey>=iKey );
  pcache1LeaveMutex(pCache->pGroup);
























  return (sqlite3_pcache_page*)pPage;

}


/*
** Implementation of the sqlite3_pcache.xUnpin method.
**
** Mark a page as unpinned (eligible for asynchronous recycling).
................................................................................
** small cells will be rare, but they are possible.
*/
#define MX_CELL(pBt) ((pBt->pageSize-8)/6)

/* Forward declarations */
typedef struct MemPage MemPage;
typedef struct BtLock BtLock;


/*
** This is a magic string that appears at the beginning of every
** SQLite database in order to identify the file as a real database.
**
** You can change this value at compile-time by specifying a
** -DSQLITE_FILE_HEADER="..." on the compiler command-line.  The
................................................................................
                       ** non-overflow cell */
  u8 *apOvfl[5];       /* Pointers to the body of overflow cells */
  BtShared *pBt;       /* Pointer to BtShared that this page is part of */
  u8 *aData;           /* Pointer to disk image of the page data */
  u8 *aDataEnd;        /* One byte past the end of usable data */
  u8 *aCellIdx;        /* The cell index area */
  DbPage *pDbPage;     /* Pager page handle */


  Pgno pgno;           /* Page number for this page */
};

/*
** The in-memory image of a disk page has the auxiliary information appended
** to the end.  EXTRA_SIZE is the number of bytes of space needed to hold
** that extra information.
................................................................................
*/
struct Btree {
  sqlite3 *db;       /* The database connection holding this btree */
  BtShared *pBt;     /* Sharable content of this btree */
  u8 inTrans;        /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
  u8 sharable;       /* True if we can share pBt with another db */
  u8 locked;         /* True if db currently has pBt locked */

  int wantToLock;    /* Number of nested calls to sqlite3BtreeEnter() */
  int nBackup;       /* Number of backup operations reading this btree */
  u32 iDataVersion;  /* Combines with pBt->pPager->iDataVersion */
  Btree *pNext;      /* List of other sharable Btrees from the same db */
  Btree *pPrev;      /* Back pointer of the same list */
#ifndef SQLITE_OMIT_SHARED_CACHE
  BtLock lock;       /* Object used to lock page 1 */
................................................................................
#define BTS_PENDING          0x0040   /* Waiting for read-locks to clear */

/*
** An instance of the following structure is used to hold information
** about a cell.  The parseCellPtr() function fills in this structure
** based on information extract from the raw disk page.
*/
typedef struct CellInfo CellInfo;
struct CellInfo {
  i64 nKey;      /* The key for INTKEY tables, or nPayload otherwise */
  u8 *pPayload;  /* Pointer to the start of payload */
  u32 nPayload;  /* Bytes of payload */
  u16 nLocal;    /* Amount of payload held locally, not on overflow */
  u16 iOverflow; /* Offset to overflow page number.  Zero if no overflow */
  u16 nSize;     /* Size of the cell content on the main b-tree page */
................................................................................
*/
static void invalidateIncrblobCursors(
  Btree *pBtree,          /* The database file to check */
  i64 iRow,               /* The rowid that might be changing */
  int isClearTable        /* True if all rows are being deleted */
){
  BtCursor *p;
  BtShared *pBt = pBtree->pBt;
  assert( sqlite3BtreeHoldsMutex(pBtree) );

  for(p=pBt->pCursor; p; p=p->pNext){
    if( (p->curFlags & BTCF_Incrblob)!=0

     && (isClearTable || p->info.nKey==iRow)
    ){
      p->eState = CURSOR_INVALID;

    }
  }
}

#else
  /* Stub function when INCRBLOB is omitted */
  #define invalidateIncrblobCursors(x,y,z)
................................................................................
** the page, 1 means the second cell, and so forth) return a pointer
** to the cell content.
**
** This routine works only for pages that do not contain overflow cells.
*/
#define findCell(P,I) \
  ((P)->aData + ((P)->maskPage & get2byte(&(P)->aCellIdx[2*(I)])))
#define findCellv2(D,M,O,I) (D+(M&get2byte(D+(O+2*(I)))))


/*


** This a more complex version of findCell() that works for
** pages that do contain overflow cells.
*/
static u8 *findOverflowCell(MemPage *pPage, int iCell){
  int i;
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  for(i=pPage->nOverflow-1; i>=0; i--){
    int k;

    k = pPage->aiOvfl[i];
    if( k<=iCell ){
      if( k==iCell ){
        return pPage->apOvfl[i];








      }
      iCell--;









    }


  }
  return findCell(pPage, iCell);
}

/*



** Parse a cell content block and fill in the CellInfo structure.  There
** are two versions of this function.  btreeParseCell() takes a 
** cell index as the second argument and btreeParseCellPtr() 
** takes a pointer to the body of the cell as its second argument.








*/
















static void btreeParseCellPtr(
  MemPage *pPage,         /* Page containing the cell */
  u8 *pCell,              /* Pointer to the cell text. */
  CellInfo *pInfo         /* Fill in this structure */
){
  u8 *pIter;              /* For scanning through pCell */
  u32 nPayload;           /* Number of bytes of cell payload */


  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( pPage->leaf==0 || pPage->leaf==1 );


  if( pPage->intKeyLeaf ){
    assert( pPage->childPtrSize==0 );
    pIter = pCell + getVarint32(pCell, nPayload);



















    pIter += getVarint(pIter, (u64*)&pInfo->nKey);
  }else if( pPage->noPayload ){
    assert( pPage->childPtrSize==4 );
    pInfo->nSize = 4 + getVarint(&pCell[4], (u64*)&pInfo->nKey);



















    pInfo->nPayload = 0;









    pInfo->nLocal = 0;
    pInfo->iOverflow = 0;
    pInfo->pPayload = 0;
    return;
  }else{















    pIter = pCell + pPage->childPtrSize;
    pIter += getVarint32(pIter, nPayload);

    pInfo->nKey = nPayload;





  }


  pInfo->nPayload = nPayload;
  pInfo->pPayload = pIter;
  testcase( nPayload==pPage->maxLocal );
  testcase( nPayload==pPage->maxLocal+1 );
  if( nPayload<=pPage->maxLocal ){
    /* This is the (easy) common case where the entire payload fits
    ** on the local page.  No overflow is required.
    */
    pInfo->nSize = nPayload + (u16)(pIter - pCell);
    if( pInfo->nSize<4 ) pInfo->nSize = 4;
    pInfo->nLocal = (u16)nPayload;
    pInfo->iOverflow = 0;
  }else{
    /* If the payload will not fit completely on the local page, we have
    ** to decide how much to store locally and how much to spill onto
    ** overflow pages.  The strategy is to minimize the amount of unused
    ** space on overflow pages while keeping the amount of local storage
    ** in between minLocal and maxLocal.
    **
    ** Warning:  changing the way overflow payload is distributed in any
    ** way will result in an incompatible file format.
    */
    int minLocal;  /* Minimum amount of payload held locally */
    int maxLocal;  /* Maximum amount of payload held locally */
    int surplus;   /* Overflow payload available for local storage */

    minLocal = pPage->minLocal;
    maxLocal = pPage->maxLocal;
    surplus = minLocal + (nPayload - minLocal)%(pPage->pBt->usableSize - 4);
    testcase( surplus==maxLocal );
    testcase( surplus==maxLocal+1 );
    if( surplus <= maxLocal ){
      pInfo->nLocal = (u16)surplus;
    }else{
      pInfo->nLocal = (u16)minLocal;
    }
    pInfo->iOverflow = (u16)(&pInfo->pPayload[pInfo->nLocal] - pCell);
    pInfo->nSize = pInfo->iOverflow + 4;
  }
}
static void btreeParseCell(
  MemPage *pPage,         /* Page containing the cell */
  int iCell,              /* The cell index.  First cell is 0 */
  CellInfo *pInfo         /* Fill in this structure */
){
  btreeParseCellPtr(pPage, findCell(pPage, iCell), pInfo);
}

/*



** Compute the total number of bytes that a Cell needs in the cell
** data area of the btree-page.  The return number includes the cell
** data header and the local payload, but not any overflow page or
** the space used by the cell pointer.



*/
static u16 cellSizePtr(MemPage *pPage, u8 *pCell){
  u8 *pIter = pCell + pPage->childPtrSize; /* For looping over bytes of pCell */
  u8 *pEnd;                                /* End mark for a varint */
  u32 nSize;                               /* Size value to return */

#ifdef SQLITE_DEBUG
  /* The value returned by this function should always be the same as
  ** the (CellInfo.nSize) value found by doing a full parse of the
  ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of
  ** this function verifies that this invariant is not violated. */
  CellInfo debuginfo;
  btreeParseCellPtr(pPage, pCell, &debuginfo);
#endif

  if( pPage->noPayload ){
    pEnd = &pIter[9];
    while( (*pIter++)&0x80 && pIter<pEnd );
    assert( pPage->childPtrSize==4 );
    return (u16)(pIter - pCell);
  }
  nSize = *pIter;
  if( nSize>=0x80 ){
    pEnd = &pIter[9];
    nSize &= 0x7f;
    do{
      nSize = (nSize<<7) | (*++pIter & 0x7f);
    }while( *(pIter)>=0x80 && pIter<pEnd );
  }
  pIter++;
  if( pPage->intKey ){
................................................................................
      nSize = minLocal;
    }
    nSize += 4 + (u16)(pIter - pCell);
  }
  assert( nSize==debuginfo.nSize || CORRUPT_DB );
  return (u16)nSize;
}





















#ifdef SQLITE_DEBUG
/* This variation on cellSizePtr() is used inside of assert() statements
** only. */
static u16 cellSize(MemPage *pPage, int iCell){
  return cellSizePtr(pPage, findCell(pPage, iCell));
}
#endif

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** If the cell pCell, part of page pPage contains a pointer
** to an overflow page, insert an entry into the pointer-map
** for the overflow page.
*/
static void ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell, int *pRC){
  CellInfo info;
  if( *pRC ) return;
  assert( pCell!=0 );
  btreeParseCellPtr(pPage, pCell, &info);
  if( info.iOverflow ){
    Pgno ovfl = get4byte(&pCell[info.iOverflow]);
    ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno, pRC);
  }
}
#endif

................................................................................
    /* These conditions have already been verified in btreeInitPage()
    ** if PRAGMA cell_size_check=ON.
    */
    if( pc<iCellFirst || pc>iCellLast ){
      return SQLITE_CORRUPT_BKPT;
    }
    assert( pc>=iCellFirst && pc<=iCellLast );
    size = cellSizePtr(pPage, &src[pc]);
    cbrk -= size;
    if( cbrk<iCellFirst || pc+size>usableSize ){
      return SQLITE_CORRUPT_BKPT;
    }
    assert( cbrk+size<=usableSize && cbrk>=iCellFirst );
    testcase( cbrk+size==usableSize );
    testcase( pc+size==usableSize );
................................................................................
** from the free-list.
**
** If no suitable space can be found on the free-list, return NULL.
**
** This function may detect corruption within pPg.  If corruption is
** detected then *pRc is set to SQLITE_CORRUPT and NULL is returned.
**
** If a slot of at least nByte bytes is found but cannot be used because 
** there are already at least 60 fragmented bytes on the page, return NULL.
** In this case, if pbDefrag parameter is not NULL, set *pbDefrag to true.
*/
static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc, int *pbDefrag){
  const int hdr = pPg->hdrOffset;
  u8 * const aData = pPg->aData;
  int iAddr;

  int pc;
  int usableSize = pPg->pBt->usableSize;

  for(iAddr=hdr+1; (pc = get2byte(&aData[iAddr]))>0; iAddr=pc){


    int size;            /* Size of the free slot */
    /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of
    ** increasing offset. */
    if( pc>usableSize-4 || pc<iAddr+4 ){
      *pRc = SQLITE_CORRUPT_BKPT;
      return 0;
    }
    /* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each
    ** freeblock form a big-endian integer which is the size of the freeblock
    ** in bytes, including the 4-byte header. */
    size = get2byte(&aData[pc+2]);
    if( size>=nByte ){
      int x = size - nByte;
      testcase( x==4 );
      testcase( x==3 );



      if( x<4 ){
        /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total
        ** number of bytes in fragments may not exceed 60. */
        if( aData[hdr+7]>=60 ){
          if( pbDefrag ) *pbDefrag = 1;
          return 0;
        }
        /* Remove the slot from the free-list. Update the number of
        ** fragmented bytes within the page. */
        memcpy(&aData[iAddr], &aData[pc], 2);
        aData[hdr+7] += (u8)x;
      }else if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){
        *pRc = SQLITE_CORRUPT_BKPT;
        return 0;
      }else{
        /* The slot remains on the free-list. Reduce its size to account
         ** for the portion used by the new allocation. */
        put2byte(&aData[pc+2], x);
      }
      return &aData[pc + x];
    }
  }



  return 0;
}

/*
** Allocate nByte bytes of space from within the B-Tree page passed
** as the first argument. Write into *pIdx the index into pPage->aData[]
................................................................................
  gap = pPage->cellOffset + 2*pPage->nCell;
  assert( gap<=65536 );
  /* EVIDENCE-OF: R-29356-02391 If the database uses a 65536-byte page size
  ** and the reserved space is zero (the usual value for reserved space)
  ** then the cell content offset of an empty page wants to be 65536.
  ** However, that integer is too large to be stored in a 2-byte unsigned
  ** integer, so a value of 0 is used in its place. */
  top = get2byteNotZero(&data[hdr+5]);
  if( gap>top || NEVER((u32)top>pPage->pBt->usableSize) ){
    /* The NEVER() is because a oversize "top" value will be blocked from
    ** reaching this point by btreeInitPage() or btreeGetUnusedPage() */


    return SQLITE_CORRUPT_BKPT;

  }

  /* If there is enough space between gap and top for one more cell pointer
  ** array entry offset, and if the freelist is not empty, then search the
  ** freelist looking for a free slot big enough to satisfy the request.
  */
  testcase( gap+2==top );
  testcase( gap+1==top );
  testcase( gap==top );
  if( gap+2<=top && (data[hdr+1] || data[hdr+2]) ){
    int bDefrag = 0;
    u8 *pSpace = pageFindSlot(pPage, nByte, &rc, &bDefrag);
    if( rc ) return rc;
    if( bDefrag ) goto defragment_page;
    if( pSpace ){
      assert( pSpace>=data && (pSpace - data)<65536 );
      *pIdx = (int)(pSpace - data);
      return SQLITE_OK;


    }
  }

  /* The request could not be fulfilled using a freelist slot.  Check
  ** to see if defragmentation is necessary.
  */
  testcase( gap+2+nByte==top );
  if( gap+2+nByte>top ){
 defragment_page:
    assert( pPage->nCell>0 || CORRUPT_DB );
    rc = defragmentPage(pPage);
    if( rc ) return rc;
    top = get2byteNotZero(&data[hdr+5]);
    assert( gap+nByte<=top );
  }

................................................................................
      iPtr = iFreeBlk;
    }
    if( iFreeBlk>iLast ) return SQLITE_CORRUPT_BKPT;
    assert( iFreeBlk>iPtr || iFreeBlk==0 );
  
    /* At this point:
    **    iFreeBlk:   First freeblock after iStart, or zero if none
    **    iPtr:       The address of a pointer iFreeBlk
    **
    ** Check to see if iFreeBlk should be coalesced onto the end of iStart.
    */
    if( iFreeBlk && iEnd+3>=iFreeBlk ){
      nFrag = iFreeBlk - iEnd;
      if( iEnd>iFreeBlk ) return SQLITE_CORRUPT_BKPT;
      iEnd = iFreeBlk + get2byte(&data[iFreeBlk+2]);

      iSize = iEnd - iStart;
      iFreeBlk = get2byte(&data[iFreeBlk]);
    }
  
    /* If iPtr is another freeblock (that is, if iPtr is not the freelist
    ** pointer in the page header) then check to see if iStart should be
    ** coalesced onto the end of iPtr.
................................................................................
  BtShared *pBt;     /* A copy of pPage->pBt */

  assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  pPage->leaf = (u8)(flagByte>>3);  assert( PTF_LEAF == 1<<3 );
  flagByte &= ~PTF_LEAF;
  pPage->childPtrSize = 4-4*pPage->leaf;

  pBt = pPage->pBt;
  if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){
    /* EVIDENCE-OF: R-03640-13415 A value of 5 means the page is an interior
    ** table b-tree page. */
    assert( (PTF_LEAFDATA|PTF_INTKEY)==5 );
    /* EVIDENCE-OF: R-20501-61796 A value of 13 means the page is a leaf
    ** table b-tree page. */
    assert( (PTF_LEAFDATA|PTF_INTKEY|PTF_LEAF)==13 );
    pPage->intKey = 1;

    pPage->intKeyLeaf = pPage->leaf;
    pPage->noPayload = !pPage->leaf;







    pPage->maxLocal = pBt->maxLeaf;
    pPage->minLocal = pBt->minLeaf;
  }else if( flagByte==PTF_ZERODATA ){
    /* EVIDENCE-OF: R-27225-53936 A value of 2 means the page is an interior
    ** index b-tree page. */
    assert( (PTF_ZERODATA)==2 );
    /* EVIDENCE-OF: R-16571-11615 A value of 10 means the page is a leaf
    ** index b-tree page. */
    assert( (PTF_ZERODATA|PTF_LEAF)==10 );
    pPage->intKey = 0;
    pPage->intKeyLeaf = 0;
    pPage->noPayload = 0;

    pPage->maxLocal = pBt->maxLocal;
    pPage->minLocal = pBt->minLocal;
  }else{
    /* EVIDENCE-OF: R-47608-56469 Any other value for the b-tree page type is
    ** an error. */
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
      for(i=0; i<pPage->nCell; i++){
        pc = get2byte(&data[cellOffset+i*2]);
        testcase( pc==iCellFirst );
        testcase( pc==iCellLast );
        if( pc<iCellFirst || pc>iCellLast ){
          return SQLITE_CORRUPT_BKPT;
        }
        sz = cellSizePtr(pPage, &data[pc]);
        testcase( pc+sz==usableSize );
        if( pc+sz>usableSize ){
          return SQLITE_CORRUPT_BKPT;
        }
      }
      if( !pPage->leaf ) iCellLast++;
    }  
................................................................................
    if( rc ) return rc;
    nCell = pPage->nCell;

    for(i=0; i<nCell; i++){
      u8 *pCell = findCell(pPage, i);
      if( eType==PTRMAP_OVERFLOW1 ){
        CellInfo info;
        btreeParseCellPtr(pPage, pCell, &info);
        if( info.iOverflow
         && pCell+info.iOverflow+3<=pPage->aData+pPage->maskPage
         && iFrom==get4byte(&pCell[info.iOverflow])
        ){
          put4byte(&pCell[info.iOverflow], iTo);
          break;
        }
................................................................................
/*
** Make sure the BtCursor* given in the argument has a valid
** BtCursor.info structure.  If it is not already valid, call
** btreeParseCell() to fill it in.
**
** BtCursor.info is a cache of the information in the current cell.
** Using this cache reduces the number of calls to btreeParseCell().
**
** 2007-06-25:  There is a bug in some versions of MSVC that cause the
** compiler to crash when getCellInfo() is implemented as a macro.
** But there is a measureable speed advantage to using the macro on gcc
** (when less compiler optimizations like -Os or -O0 are used and the
** compiler is not doing aggressive inlining.)  So we use a real function
** for MSVC and a macro for everything else.  Ticket #2457.
*/
#ifndef NDEBUG
  static void assertCellInfo(BtCursor *pCur){
    CellInfo info;
    int iPage = pCur->iPage;
    memset(&info, 0, sizeof(info));
    btreeParseCell(pCur->apPage[iPage], pCur->aiIdx[iPage], &info);
    assert( CORRUPT_DB || memcmp(&info, &pCur->info, sizeof(info))==0 );
  }
#else
  #define assertCellInfo(x)
#endif
#ifdef _MSC_VER
  /* Use a real function in MSVC to work around bugs in that compiler. */
  static void getCellInfo(BtCursor *pCur){
    if( pCur->info.nSize==0 ){
      int iPage = pCur->iPage;
      btreeParseCell(pCur->apPage[iPage],pCur->aiIdx[iPage],&pCur->info);
      pCur->curFlags |= BTCF_ValidNKey;

    }else{
      assertCellInfo(pCur);
    }
  }
#else /* if not _MSC_VER */
  /* Use a macro in all other compilers so that the function is inlined */
#define getCellInfo(pCur)                                                      \
  if( pCur->info.nSize==0 ){                                                   \
    int iPage = pCur->iPage;                                                   \
    btreeParseCell(pCur->apPage[iPage],pCur->aiIdx[iPage],&pCur->info);        \
    pCur->curFlags |= BTCF_ValidNKey;                                          \
  }else{                                                                       \
    assertCellInfo(pCur);                                                      \
  }
#endif /* _MSC_VER */

#ifndef NDEBUG  /* The next routine used only within assert() statements */
/*
** Return true if the given BtCursor is valid.  A valid cursor is one
** that is currently pointing to a row in a (non-empty) table.
** This is a verification routine is used only within assert() statements.
*/
................................................................................
          **
          ** If the record is corrupt, the xRecordCompare routine may read
          ** up to two varints past the end of the buffer. An extra 18 
          ** bytes of padding is allocated at the end of the buffer in
          ** case this happens.  */
          void *pCellKey;
          u8 * const pCellBody = pCell - pPage->childPtrSize;
          btreeParseCellPtr(pPage, pCellBody, &pCur->info);
          nCell = (int)pCur->info.nKey;
          testcase( nCell<0 );   /* True if key size is 2^32 or more */
          testcase( nCell==0 );  /* Invalid key size:  0x80 0x80 0x00 */
          testcase( nCell==1 );  /* Invalid key size:  0x80 0x80 0x01 */
          testcase( nCell==2 );  /* Minimum legal index key size */
          if( nCell<2 ){
            rc = SQLITE_CORRUPT_BKPT;
................................................................................
  if( n>=mxPage ){
    return SQLITE_CORRUPT_BKPT;
  }
  if( n>0 ){
    /* There are pages on the freelist.  Reuse one of those pages. */
    Pgno iTrunk;
    u8 searchList = 0; /* If the free-list must be searched for 'nearby' */

    
    /* If eMode==BTALLOC_EXACT and a query of the pointer-map
    ** shows that the page 'nearby' is somewhere on the free-list, then
    ** the entire-list will be searched for that page.
    */
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( eMode==BTALLOC_EXACT ){
................................................................................
      }else{
        /* EVIDENCE-OF: R-59841-13798 The 4-byte big-endian integer at offset 32
        ** stores the page number of the first page of the freelist, or zero if
        ** the freelist is empty. */
        iTrunk = get4byte(&pPage1->aData[32]);
      }
      testcase( iTrunk==mxPage );
      if( iTrunk>mxPage ){
        rc = SQLITE_CORRUPT_BKPT;
      }else{
        rc = btreeGetUnusedPage(pBt, iTrunk, &pTrunk, 0);
      }
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
................................................................................
  CellInfo info;
  Pgno ovflPgno;
  int rc;
  int nOvfl;
  u32 ovflPageSize;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  btreeParseCellPtr(pPage, pCell, &info);
  *pnSize = info.nSize;
  if( info.iOverflow==0 ){
    return SQLITE_OK;  /* No overflow pages. Return without doing anything */
  }
  if( pCell+info.iOverflow+3 > pPage->aData+pPage->maskPage ){
    return SQLITE_CORRUPT_BKPT;  /* Cell extends past end of page */
  }
................................................................................
  **
  ** Use a call to btreeParseCellPtr() to verify that the values above
  ** were computed correctly.
  */
#if SQLITE_DEBUG
  {
    CellInfo info;
    btreeParseCellPtr(pPage, pCell, &info);
    assert( nHeader=(int)(info.pPayload - pCell) );
    assert( info.nKey==nKey );
    assert( *pnSize == info.nSize );
    assert( spaceLeft == info.nLocal );
    assert( pPrior == &pCell[info.iOverflow] );
  }
#endif
................................................................................
  int sz,           /* Bytes of content in pCell */
  u8 *pTemp,        /* Temp storage space for pCell, if needed */
  Pgno iChild,      /* If non-zero, replace first 4 bytes with this value */
  int *pRC          /* Read and write return code from here */
){
  int idx = 0;      /* Where to write new cell content in data[] */
  int j;            /* Loop counter */
  int end;          /* First byte past the last cell pointer in data[] */
  int ins;          /* Index in data[] where new cell pointer is inserted */
  int cellOffset;   /* Address of first cell pointer in data[] */
  u8 *data;         /* The content of the whole page */


  if( *pRC ) return;

  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
  assert( MX_CELL(pPage->pBt)<=10921 );
  assert( pPage->nCell<=MX_CELL(pPage->pBt) || CORRUPT_DB );
  assert( pPage->nOverflow<=ArraySize(pPage->apOvfl) );
................................................................................
  assert( ArraySize(pPage->apOvfl)==ArraySize(pPage->aiOvfl) );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  /* The cell should normally be sized correctly.  However, when moving a
  ** malformed cell from a leaf page to an interior page, if the cell size
  ** wanted to be less than 4 but got rounded up to 4 on the leaf, then size
  ** might be less than 8 (leaf-size + pointer) on the interior node.  Hence
  ** the term after the || in the following assert(). */
  assert( sz==cellSizePtr(pPage, pCell) || (sz==8 && iChild>0) );
  if( pPage->nOverflow || sz+2>pPage->nFree ){
    if( pTemp ){
      memcpy(pTemp, pCell, sz);
      pCell = pTemp;
    }
    if( iChild ){
      put4byte(pCell, iChild);
    }
    j = pPage->nOverflow++;
    assert( j<(int)(sizeof(pPage->apOvfl)/sizeof(pPage->apOvfl[0])) );
    pPage->apOvfl[j] = pCell;
    pPage->aiOvfl[j] = (u16)i;








  }else{
    int rc = sqlite3PagerWrite(pPage->pDbPage);
    if( rc!=SQLITE_OK ){
      *pRC = rc;
      return;
    }
    assert( sqlite3PagerIswriteable(pPage->pDbPage) );
    data = pPage->aData;
    cellOffset = pPage->cellOffset;
    end = cellOffset + 2*pPage->nCell;
    ins = cellOffset + 2*i;
    rc = allocateSpace(pPage, sz, &idx);
    if( rc ){ *pRC = rc; return; }
    /* The allocateSpace() routine guarantees the following two properties
    ** if it returns success */
    assert( idx >= end+2 );

    assert( idx+sz <= (int)pPage->pBt->usableSize );
    pPage->nCell++;
    pPage->nFree -= (u16)(2 + sz);
    memcpy(&data[idx], pCell, sz);
    if( iChild ){
      put4byte(&data[idx], iChild);
    }
    memmove(&data[ins+2], &data[ins], end-ins);

    put2byte(&data[ins], idx);



    put2byte(&data[pPage->hdrOffset+3], pPage->nCell);
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pPage->pBt->autoVacuum ){
      /* The cell may contain a pointer to an overflow page. If so, write
      ** the entry for the overflow page into the pointer map.
      */
      ptrmapPutOvflPtr(pPage, pCell, pRC);
    }
#endif
  }
}















































/*
** Array apCell[] contains pointers to nCell b-tree page cells. The 
** szCell[] array contains the size in bytes of each cell. This function
** replaces the current contents of page pPg with the contents of the cell
** array.
**
................................................................................
** Some of the cells in apCell[] may currently be stored in pPg. This
** function works around problems caused by this by making a copy of any 
** such cells before overwriting the page data.
**
** The MemPage.nFree field is invalidated by this function. It is the 
** responsibility of the caller to set it correctly.
*/
static void rebuildPage(
  MemPage *pPg,                   /* Edit this page */
  int nCell,                      /* Final number of cells on page */
  u8 **apCell,                    /* Array of cells */
  u16 *szCell                     /* Array of cell sizes */
){
  const int hdr = pPg->hdrOffset;          /* Offset of header on pPg */
  u8 * const aData = pPg->aData;           /* Pointer to data for pPg */
................................................................................
  pData = pEnd;
  for(i=0; i<nCell; i++){
    u8 *pCell = apCell[i];
    if( pCell>aData && pCell<pEnd ){
      pCell = &pTmp[pCell - aData];
    }
    pData -= szCell[i];
    memcpy(pData, pCell, szCell[i]);
    put2byte(pCellptr, (pData - aData));
    pCellptr += 2;


    assert( szCell[i]==cellSizePtr(pPg, pCell) || CORRUPT_DB );
    testcase( szCell[i]==cellSizePtr(pPg,pCell) );
  }

  /* The pPg->nFree field is now set incorrectly. The caller will fix it. */
  pPg->nCell = nCell;
  pPg->nOverflow = 0;

  put2byte(&aData[hdr+1], 0);
  put2byte(&aData[hdr+3], pPg->nCell);
  put2byte(&aData[hdr+5], pData - aData);
  aData[hdr+7] = 0x00;

}

/*
** Array apCell[] contains nCell pointers to b-tree cells. Array szCell
** contains the size in bytes of each such cell. This function attempts to 
** add the cells stored in the array to page pPg. If it cannot (because 
** the page needs to be defragmented before the cells will fit), non-zero
................................................................................
** cells in apCell[], then the cells do not fit and non-zero is returned.
*/
static int pageInsertArray(
  MemPage *pPg,                   /* Page to add cells to */
  u8 *pBegin,                     /* End of cell-pointer array */
  u8 **ppData,                    /* IN/OUT: Page content -area pointer */
  u8 *pCellptr,                   /* Pointer to cell-pointer area */
  int nCell,                      /* Number of cells to add to pPg */
  u8 **apCell,                    /* Array of cells */
  u16 *szCell                     /* Array of cell sizes */
){
  int i;
  u8 *aData = pPg->aData;
  u8 *pData = *ppData;
  const int bFreelist = aData[1] || aData[2];
  assert( CORRUPT_DB || pPg->hdrOffset==0 );    /* Never called on page 1 */
  for(i=0; i<nCell; i++){
    int sz = szCell[i];
    int rc;
    u8 *pSlot;

    if( bFreelist==0 || (pSlot = pageFindSlot(pPg, sz, &rc, 0))==0 ){
      pData -= sz;
      if( pData<pBegin ) return 1;
      pSlot = pData;
    }
    memcpy(pSlot, apCell[i], sz);
    put2byte(pCellptr, (pSlot - aData));
    pCellptr += 2;
  }
  *ppData = pData;
  return 0;
}

................................................................................
** within the body of pPg to the pPg free-list. The cell-pointers and other
** fields of the page are not updated.
**
** This function returns the total number of cells added to the free-list.
*/
static int pageFreeArray(
  MemPage *pPg,                   /* Page to edit */
  int nCell,                      /* Cells to delete */
  u8 **apCell,                    /* Array of cells */
  u16 *szCell                     /* Array of cell sizes */
){
  u8 * const aData = pPg->aData;
  u8 * const pEnd = &aData[pPg->pBt->usableSize];
  u8 * const pStart = &aData[pPg->hdrOffset + 8 + pPg->childPtrSize];
  int nRet = 0;
  int i;

  u8 *pFree = 0;
  int szFree = 0;

  for(i=0; i<nCell; i++){
    u8 *pCell = apCell[i];
    if( pCell>=pStart && pCell<pEnd ){
      int sz = szCell[i];




      if( pFree!=(pCell + sz) ){
        if( pFree ){
          assert( pFree>aData && (pFree - aData)<65536 );
          freeSpace(pPg, (u16)(pFree - aData), szFree);
        }
        pFree = pCell;
        szFree = sz;
................................................................................
**
** This routine makes the necessary adjustments to pPg so that it contains
** the correct cells after being balanced.
**
** The pPg->nFree field is invalid when this function returns. It is the
** responsibility of the caller to set it correctly.
*/
static void editPage(
  MemPage *pPg,                   /* Edit this page */
  int iOld,                       /* Index of first cell currently on page */
  int iNew,                       /* Index of new first cell on page */
  int nNew,                       /* Final number of cells on page */
  u8 **apCell,                    /* Array of cells */
  u16 *szCell                     /* Array of cell sizes */
){
  u8 * const aData = pPg->aData;
  const int hdr = pPg->hdrOffset;
  u8 *pBegin = &pPg->aCellIdx[nNew * 2];
  int nCell = pPg->nCell;       /* Cells stored on pPg */
  u8 *pData;
  u8 *pCellptr;
................................................................................
#ifdef SQLITE_DEBUG
  u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager);
  memcpy(pTmp, aData, pPg->pBt->usableSize);
#endif

  /* Remove cells from the start and end of the page */
  if( iOld<iNew ){
    int nShift = pageFreeArray(
        pPg, iNew-iOld, &apCell[iOld], &szCell[iOld]
    );
    memmove(pPg->aCellIdx, &pPg->aCellIdx[nShift*2], nCell*2);
    nCell -= nShift;
  }
  if( iNewEnd < iOldEnd ){
    nCell -= pageFreeArray(
        pPg, iOldEnd-iNewEnd, &apCell[iNewEnd], &szCell[iNewEnd]
    );
  }

  pData = &aData[get2byteNotZero(&aData[hdr+5])];
  if( pData<pBegin ) goto editpage_fail;

  /* Add cells to the start of the page */
  if( iNew<iOld ){
    int nAdd = MIN(nNew,iOld-iNew);
    assert( (iOld-iNew)<nNew || nCell==0 || CORRUPT_DB );
    pCellptr = pPg->aCellIdx;
    memmove(&pCellptr[nAdd*2], pCellptr, nCell*2);
    if( pageInsertArray(
          pPg, pBegin, &pData, pCellptr,
          nAdd, &apCell[iNew], &szCell[iNew]
    ) ) goto editpage_fail;
    nCell += nAdd;
  }

  /* Add any overflow cells */
  for(i=0; i<pPg->nOverflow; i++){
    int iCell = (iOld + pPg->aiOvfl[i]) - iNew;
    if( iCell>=0 && iCell<nNew ){
      pCellptr = &pPg->aCellIdx[iCell * 2];
      memmove(&pCellptr[2], pCellptr, (nCell - iCell) * 2);
      nCell++;
      if( pageInsertArray(
            pPg, pBegin, &pData, pCellptr,
            1, &apCell[iCell + iNew], &szCell[iCell + iNew]
      ) ) goto editpage_fail;
    }
  }

  /* Append cells to the end of the page */
  pCellptr = &pPg->aCellIdx[nCell*2];
  if( pageInsertArray(
        pPg, pBegin, &pData, pCellptr,
        nNew-nCell, &apCell[iNew+nCell], &szCell[iNew+nCell]
  ) ) goto editpage_fail;

  pPg->nCell = nNew;
  pPg->nOverflow = 0;

  put2byte(&aData[hdr+3], pPg->nCell);
  put2byte(&aData[hdr+5], pData - aData);

#ifdef SQLITE_DEBUG
  for(i=0; i<nNew && !CORRUPT_DB; i++){
    u8 *pCell = apCell[i+iNew];
    int iOff = get2byte(&pPg->aCellIdx[i*2]);
    if( pCell>=aData && pCell<&aData[pPg->pBt->usableSize] ){
      pCell = &pTmp[pCell - aData];
    }
    assert( 0==memcmp(pCell, &aData[iOff], szCell[i+iNew]) );

  }
#endif

  return;
 editpage_fail:
  /* Unable to edit this page. Rebuild it from scratch instead. */
  rebuildPage(pPg, nNew, &apCell[iNew], &szCell[iNew]);

}

/*
** The following parameters determine how many adjacent pages get involved
** in a balancing operation.  NN is the number of neighbors on either side
** of the page that participate in the balancing operation.  NB is the
** total number of pages that participate, including the target page and
................................................................................
  */
  rc = allocateBtreePage(pBt, &pNew, &pgnoNew, 0, 0);

  if( rc==SQLITE_OK ){

    u8 *pOut = &pSpace[4];
    u8 *pCell = pPage->apOvfl[0];
    u16 szCell = cellSizePtr(pPage, pCell);
    u8 *pStop;

    assert( sqlite3PagerIswriteable(pNew->pDbPage) );
    assert( pPage->aData[0]==(PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF) );
    zeroPage(pNew, PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF);
    rebuildPage(pNew, 1, &pCell, &szCell);

    pNew->nFree = pBt->usableSize - pNew->cellOffset - 2 - szCell;

    /* If this is an auto-vacuum database, update the pointer map
    ** with entries for the new page, and any pointer from the 
    ** cell on the page to an overflow page. If either of these
    ** operations fails, the return code is set, but the contents
    ** of the parent page are still manipulated by thh code below.
................................................................................
    assert( pPage->isInit );

    for(j=0; j<pPage->nCell; j++){
      CellInfo info;
      u8 *z;
     
      z = findCell(pPage, j);
      btreeParseCellPtr(pPage, z, &info);
      if( info.iOverflow ){
        Pgno ovfl = get4byte(&z[info.iOverflow]);
        ptrmapGet(pBt, ovfl, &e, &n);
        assert( n==pPage->pgno && e==PTRMAP_OVERFLOW1 );
      }
      if( !pPage->leaf ){
        Pgno child = get4byte(z);
................................................................................
  MemPage *pParent,               /* Parent page of siblings being balanced */
  int iParentIdx,                 /* Index of "the page" in pParent */
  u8 *aOvflSpace,                 /* page-size bytes of space for parent ovfl */
  int isRoot,                     /* True if pParent is a root-page */
  int bBulk                       /* True if this call is part of a bulk load */
){
  BtShared *pBt;               /* The whole database */
  int nCell = 0;               /* Number of cells in apCell[] */
  int nMaxCells = 0;           /* Allocated size of apCell, szCell, aFrom. */
  int nNew = 0;                /* Number of pages in apNew[] */
  int nOld;                    /* Number of pages in apOld[] */
  int i, j, k;                 /* Loop counters */
  int nxDiv;                   /* Next divider slot in pParent->aCell[] */
  int rc = SQLITE_OK;          /* The return code */
  u16 leafCorrection;          /* 4 if pPage is a leaf.  0 if not */
  int leafData;                /* True if pPage is a leaf of a LEAFDATA tree */
  int usableSpace;             /* Bytes in pPage beyond the header */
  int pageFlags;               /* Value of pPage->aData[0] */
  int subtotal;                /* Subtotal of bytes in cells on one page */
  int iSpace1 = 0;             /* First unused byte of aSpace1[] */
  int iOvflSpace = 0;          /* First unused byte of aOvflSpace[] */
  int szScratch;               /* Size of scratch memory requested */
  MemPage *apOld[NB];          /* pPage and up to two siblings */
  MemPage *apNew[NB+2];        /* pPage and up to NB siblings after balancing */
  u8 *pRight;                  /* Location in parent of right-sibling pointer */
  u8 *apDiv[NB-1];             /* Divider cells in pParent */
  int cntNew[NB+2];            /* Index in aCell[] of cell after i-th page */
  int cntOld[NB+2];            /* Old index in aCell[] after i-th page */
  int szNew[NB+2];             /* Combined size of cells placed on i-th page */
  u8 **apCell = 0;             /* All cells begin balanced */
  u16 *szCell;                 /* Local size of all cells in apCell[] */
  u8 *aSpace1;                 /* Space for copies of dividers cells */
  Pgno pgno;                   /* Temp var to store a page number in */
  u8 abDone[NB+2];             /* True after i'th new page is populated */
  Pgno aPgno[NB+2];            /* Page numbers of new pages before shuffling */
  Pgno aPgOrder[NB+2];         /* Copy of aPgno[] used for sorting pages */
  u16 aPgFlags[NB+2];          /* flags field of new pages before shuffling */


  memset(abDone, 0, sizeof(abDone));


  pBt = pParent->pBt;
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( sqlite3PagerIswriteable(pParent->pDbPage) );

#if 0
  TRACE(("BALANCE: begin page %d child of %d\n", pPage->pgno, pParent->pgno));
#endif
................................................................................
    }
    nMaxCells += 1+apOld[i]->nCell+apOld[i]->nOverflow;
    if( (i--)==0 ) break;

    if( i+nxDiv==pParent->aiOvfl[0] && pParent->nOverflow ){
      apDiv[i] = pParent->apOvfl[0];
      pgno = get4byte(apDiv[i]);
      szNew[i] = cellSizePtr(pParent, apDiv[i]);
      pParent->nOverflow = 0;
    }else{
      apDiv[i] = findCell(pParent, i+nxDiv-pParent->nOverflow);
      pgno = get4byte(apDiv[i]);
      szNew[i] = cellSizePtr(pParent, apDiv[i]);

      /* Drop the cell from the parent page. apDiv[i] still points to
      ** the cell within the parent, even though it has been dropped.
      ** This is safe because dropping a cell only overwrites the first
      ** four bytes of it, and this function does not need the first
      ** four bytes of the divider cell. So the pointer is safe to use
      ** later on.  
................................................................................
  ** alignment */
  nMaxCells = (nMaxCells + 3)&~3;

  /*
  ** Allocate space for memory structures
  */
  szScratch =
       nMaxCells*sizeof(u8*)                       /* apCell */
     + nMaxCells*sizeof(u16)                       /* szCell */
     + pBt->pageSize;                              /* aSpace1 */

  /* EVIDENCE-OF: R-28375-38319 SQLite will never request a scratch buffer
  ** that is more than 6 times the database page size. */
  assert( szScratch<=6*(int)pBt->pageSize );
  apCell = sqlite3ScratchMalloc( szScratch ); 
  if( apCell==0 ){
    rc = SQLITE_NOMEM;
    goto balance_cleanup;
  }
  szCell = (u16*)&apCell[nMaxCells];
  aSpace1 = (u8*)&szCell[nMaxCells];
  assert( EIGHT_BYTE_ALIGNMENT(aSpace1) );

  /*
  ** Load pointers to all cells on sibling pages and the divider cells
  ** into the local apCell[] array.  Make copies of the divider cells
  ** into space obtained from aSpace1[]. The divider cells have already
  ** been removed from pParent.
  **
  ** If the siblings are on leaf pages, then the child pointers of the
  ** divider cells are stripped from the cells before they are copied
  ** into aSpace1[].  In this way, all cells in apCell[] are without
  ** child pointers.  If siblings are not leaves, then all cell in
  ** apCell[] include child pointers.  Either way, all cells in apCell[]
  ** are alike.
  **
  ** leafCorrection:  4 if pPage is a leaf.  0 if pPage is not a leaf.
  **       leafData:  1 if pPage holds key+data and pParent holds only keys.
  */

  leafCorrection = apOld[0]->leaf*4;
  leafData = apOld[0]->intKeyLeaf;
  for(i=0; i<nOld; i++){
    int limit;
    MemPage *pOld = apOld[i];






    /* Verify that all sibling pages are of the same "type" (table-leaf,
    ** table-interior, index-leaf, or index-interior).
    */
    if( pOld->aData[0]!=apOld[0]->aData[0] ){
      rc = SQLITE_CORRUPT_BKPT;
      goto balance_cleanup;
    }

    limit = pOld->nCell+pOld->nOverflow;

















    if( pOld->nOverflow>0 ){


      for(j=0; j<limit; j++){
        assert( nCell<nMaxCells );
        apCell[nCell] = findOverflowCell(pOld, j);
        szCell[nCell] = cellSizePtr(pOld, apCell[nCell]);


        nCell++;
      }
    }else{
      u8 *aData = pOld->aData;
      u16 maskPage = pOld->maskPage;






      u16 cellOffset = pOld->cellOffset;
      for(j=0; j<limit; j++){

        assert( nCell<nMaxCells );
        apCell[nCell] = findCellv2(aData, maskPage, cellOffset, j);
        szCell[nCell] = cellSizePtr(pOld, apCell[nCell]);


        nCell++;
      }
    }       
    cntOld[i] = nCell;
    if( i<nOld-1 && !leafData){
      u16 sz = (u16)szNew[i];
      u8 *pTemp;
      assert( nCell<nMaxCells );
      szCell[nCell] = sz;
      pTemp = &aSpace1[iSpace1];
      iSpace1 += sz;
      assert( sz<=pBt->maxLocal+23 );
      assert( iSpace1 <= (int)pBt->pageSize );
      memcpy(pTemp, apDiv[i], sz);
      apCell[nCell] = pTemp+leafCorrection;
      assert( leafCorrection==0 || leafCorrection==4 );
      szCell[nCell] = szCell[nCell] - leafCorrection;
      if( !pOld->leaf ){
        assert( leafCorrection==0 );
        assert( pOld->hdrOffset==0 );
        /* The right pointer of the child page pOld becomes the left
        ** pointer of the divider cell */
        memcpy(apCell[nCell], &pOld->aData[8], 4);
      }else{
        assert( leafCorrection==4 );
        while( szCell[nCell]<4 ){
          /* Do not allow any cells smaller than 4 bytes. If a smaller cell
          ** does exist, pad it with 0x00 bytes. */
          assert( szCell[nCell]==3 || CORRUPT_DB );
          assert( apCell[nCell]==&aSpace1[iSpace1-3] || CORRUPT_DB );
          aSpace1[iSpace1++] = 0x00;
          szCell[nCell]++;
        }
      }
      nCell++;
    }
  }

  /*
  ** Figure out the number of pages needed to hold all nCell cells.
  ** Store this number in "k".  Also compute szNew[] which is the total
  ** size of all cells on the i-th page and cntNew[] which is the index
  ** in apCell[] of the cell that divides page i from page i+1.  
  ** cntNew[k] should equal nCell.
  **
  ** Values computed by this block:
  **
  **           k: The total number of sibling pages
  **    szNew[i]: Spaced used on the i-th sibling page.
  **   cntNew[i]: Index in apCell[] and szCell[] for the first cell to
  **              the right of the i-th sibling page.
  ** usableSpace: Number of bytes of space available on each sibling.
  ** 
  */
  usableSpace = pBt->usableSize - 12 + leafCorrection;
  for(subtotal=k=i=0; i<nCell; i++){
    assert( i<nMaxCells );
    subtotal += szCell[i] + 2;









    if( subtotal > usableSpace ){
      szNew[k] = subtotal - szCell[i] - 2;




      cntNew[k] = i;



      if( leafData ){ i--; }



      subtotal = 0;









      k++;












      if( k>NB+1 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }

    }
  }
  szNew[k] = subtotal;
  cntNew[k] = nCell;
  k++;

  /*
  ** The packing computed by the previous block is biased toward the siblings
  ** on the left side (siblings with smaller keys). The left siblings are
  ** always nearly full, while the right-most sibling might be nearly empty.
  ** The next block of code attempts to adjust the packing of siblings to
  ** get a better balance.
................................................................................
    int szRight = szNew[i];  /* Size of sibling on the right */
    int szLeft = szNew[i-1]; /* Size of sibling on the left */
    int r;              /* Index of right-most cell in left sibling */
    int d;              /* Index of first cell to the left of right sibling */

    r = cntNew[i-1] - 1;
    d = r + 1 - leafData;


    assert( d<nMaxCells );
    assert( r<nMaxCells );

    while( szRight==0 
       || (!bBulk && szRight+szCell[d]+2<=szLeft-(szCell[r]+2)) 
    ){



      szRight += szCell[d] + 2;
      szLeft -= szCell[r] + 2;
      cntNew[i-1]--;
      r = cntNew[i-1] - 1;
      d = r + 1 - leafData;
    }



    szNew[i] = szRight;
    szNew[i-1] = szLeft;




  }

  /* Sanity check:  For a non-corrupt database file one of the follwing
  ** must be true:
  **    (1) We found one or more cells (cntNew[0])>0), or
  **    (2) pPage is a virtual root page.  A virtual root page is when
  **        the real root page is page 1 and we are the only child of
................................................................................
    }else{
      assert( i>0 );
      rc = allocateBtreePage(pBt, &pNew, &pgno, (bBulk ? 1 : pgno), 0);
      if( rc ) goto balance_cleanup;
      zeroPage(pNew, pageFlags);
      apNew[i] = pNew;
      nNew++;
      cntOld[i] = nCell;

      /* Set the pointer-map entry for the new sibling page. */
      if( ISAUTOVACUUM ){
        ptrmapPut(pBt, pNew->pgno, PTRMAP_BTREE, pParent->pgno, &rc);
        if( rc!=SQLITE_OK ){
          goto balance_cleanup;
        }
................................................................................
    MemPage *pNew = apNew[0];
    u8 *aOld = pNew->aData;
    int cntOldNext = pNew->nCell + pNew->nOverflow;
    int usableSize = pBt->usableSize;
    int iNew = 0;
    int iOld = 0;

    for(i=0; i<nCell; i++){
      u8 *pCell = apCell[i];
      if( i==cntOldNext ){
        MemPage *pOld = (++iOld)<nNew ? apNew[iOld] : apOld[iOld];
        cntOldNext += pOld->nCell + pOld->nOverflow + !leafData;
        aOld = pOld->aData;
      }
      if( i==cntNew[iNew] ){
        pNew = apNew[++iNew];
................................................................................
       || pNew->pgno!=aPgno[iOld]
       || pCell<aOld
       || pCell>=&aOld[usableSize]
      ){
        if( !leafCorrection ){
          ptrmapPut(pBt, get4byte(pCell), PTRMAP_BTREE, pNew->pgno, &rc);
        }
        if( szCell[i]>pNew->minLocal ){
          ptrmapPutOvflPtr(pNew, pCell, &rc);
        }

      }
    }
  }

  /* Insert new divider cells into pParent. */
  for(i=0; i<nNew-1; i++){
    u8 *pCell;
    u8 *pTemp;
    int sz;
    MemPage *pNew = apNew[i];
    j = cntNew[i];

    assert( j<nMaxCells );

    pCell = apCell[j];
    sz = szCell[j] + leafCorrection;
    pTemp = &aOvflSpace[iOvflSpace];
    if( !pNew->leaf ){
      memcpy(&pNew->aData[8], pCell, 4);
    }else if( leafData ){
      /* If the tree is a leaf-data tree, and the siblings are leaves, 
      ** then there is no divider cell in apCell[]. Instead, the divider 
      ** cell consists of the integer key for the right-most cell of 
      ** the sibling-page assembled above only.
      */
      CellInfo info;
      j--;
      btreeParseCellPtr(pNew, apCell[j], &info);
      pCell = pTemp;
      sz = 4 + putVarint(&pCell[4], info.nKey);
      pTemp = 0;
    }else{
      pCell -= 4;
      /* Obscure case for non-leaf-data trees: If the cell at pCell was
      ** previously stored on a leaf node, and its reported size was 4
................................................................................
      ** any cell). But it is important to pass the correct size to 
      ** insertCell(), so reparse the cell now.
      **
      ** Note that this can never happen in an SQLite data file, as all
      ** cells are at least 4 bytes. It only happens in b-trees used
      ** to evaluate "IN (SELECT ...)" and similar clauses.
      */
      if( szCell[j]==4 ){
        assert(leafCorrection==4);
        sz = cellSizePtr(pParent, pCell);
      }
    }
    iOvflSpace += sz;
    assert( sz<=pBt->maxLocal+23 );
    assert( iOvflSpace <= (int)pBt->pageSize );
    insertCell(pParent, nxDiv+i, pCell, sz, pTemp, pNew->pgno, &rc);
    if( rc!=SQLITE_OK ) goto balance_cleanup;
................................................................................
      ** only after iPg+1 has already been updated. */
      assert( cntNew[iPg]>=cntOld[iPg] || abDone[iPg+1] );

      if( iPg==0 ){
        iNew = iOld = 0;
        nNewCell = cntNew[0];
      }else{
        iOld = iPg<nOld ? (cntOld[iPg-1] + !leafData) : nCell;
        iNew = cntNew[iPg-1] + !leafData;
        nNewCell = cntNew[iPg] - iNew;
      }

      editPage(apNew[iPg], iOld, iNew, nNewCell, apCell, szCell);

      abDone[iPg]++;
      apNew[iPg]->nFree = usableSpace-szNew[iPg];
      assert( apNew[iPg]->nOverflow==0 );
      assert( apNew[iPg]->nCell==nNewCell );
    }
  }

................................................................................
      u32 key = get4byte(&apNew[i]->aData[8]);
      ptrmapPut(pBt, key, PTRMAP_BTREE, apNew[i]->pgno, &rc);
    }
  }

  assert( pParent->isInit );
  TRACE(("BALANCE: finished: old=%d new=%d cells=%d\n",
          nOld, nNew, nCell));

  /* Free any old pages that were not reused as new pages.
  */
  for(i=nNew; i<nOld; i++){
    freePage(apOld[i], &rc);
  }

................................................................................
  }
#endif

  /*
  ** Cleanup before returning.
  */
balance_cleanup:
  sqlite3ScratchFree(apCell);
  for(i=0; i<nOld; i++){
    releasePage(apOld[i]);
  }
  for(i=0; i<nNew; i++){
    releasePage(apNew[i]);
  }

................................................................................
          pCur->pgnoRoot, nKey, nData, pPage->pgno,
          loc==0 ? "overwrite" : "new entry"));
  assert( pPage->isInit );
  newCell = pBt->pTmpSpace;
  assert( newCell!=0 );
  rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, nZero, &szNew);
  if( rc ) goto end_insert;
  assert( szNew==cellSizePtr(pPage, newCell) );
  assert( szNew <= MX_CELL_SIZE(pBt) );
  idx = pCur->aiIdx[pCur->iPage];
  if( loc==0 ){
    u16 szOld;
    assert( idx<pPage->nCell );
    rc = sqlite3PagerWrite(pPage->pDbPage);
    if( rc ){
................................................................................
    MemPage *pLeaf = pCur->apPage[pCur->iPage];
    int nCell;
    Pgno n = pCur->apPage[iCellDepth+1]->pgno;
    unsigned char *pTmp;

    pCell = findCell(pLeaf, pLeaf->nCell-1);
    if( pCell<&pLeaf->aData[4] ) return SQLITE_CORRUPT_BKPT;
    nCell = cellSizePtr(pLeaf, pCell);
    assert( MX_CELL_SIZE(pBt) >= nCell );
    pTmp = pBt->pTmpSpace;
    assert( pTmp!=0 );
    rc = sqlite3PagerWrite(pLeaf->pDbPage);
    insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc);
    dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc);
    if( rc ) return rc;
................................................................................

    /* Check payload overflow pages
    */
    pCheck->zPfx = "On tree page %d cell %d: ";
    pCheck->v1 = iPage;
    pCheck->v2 = i;
    pCell = findCell(pPage,i);
    btreeParseCellPtr(pPage, pCell, &info);
    sz = info.nPayload;
    /* For intKey pages, check that the keys are in order.
    */
    if( pPage->intKey ){
      if( i==0 ){
        nMinKey = nMaxKey = info.nKey;
      }else if( info.nKey <= nMaxKey ){
................................................................................
    cellStart = hdr + 12 - 4*pPage->leaf;
    /* EVIDENCE-OF: R-02776-14802 The cell pointer array consists of K 2-byte
    ** integer offsets to the cell contents. */
    for(i=0; i<nCell; i++){
      int pc = get2byte(&data[cellStart+i*2]);
      u32 size = 65536;
      if( pc<=usableSize-4 ){
        size = cellSizePtr(pPage, &data[pc]);
      }
      if( (int)(pc+size-1)>=usableSize ){
        pCheck->zPfx = 0;
        checkAppendMsg(pCheck,
            "Corruption detected in cell %d on page %d",i,iPage);
      }else{
        btreeHeapInsert(heap, (pc<<16)|(pc+size-1));
................................................................................
}

/* 
** Mark this cursor as an incremental blob cursor.
*/
SQLITE_PRIVATE void sqlite3BtreeIncrblobCursor(BtCursor *pCur){
  pCur->curFlags |= BTCF_Incrblob;

}
#endif

/*
** Set both the "read version" (single byte at byte offset 18) and 
** "write version" (single byte at byte offset 19) fields in the database
** header to iVersion.
................................................................................
** is forced.  In other words, the value is converted into the desired
** affinity even if that results in loss of data.  This routine is
** used (for example) to implement the SQL "cast()" operator.
*/
SQLITE_PRIVATE void sqlite3VdbeMemCast(Mem *pMem, u8 aff, u8 encoding){
  if( pMem->flags & MEM_Null ) return;
  switch( aff ){
    case SQLITE_AFF_NONE: {   /* Really a cast to BLOB */
      if( (pMem->flags & MEM_Blob)==0 ){
        sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
        assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
        MemSetTypeFlag(pMem, MEM_Blob);
      }else{
        pMem->flags &= ~(MEM_TypeMask&~MEM_Blob);
      }
................................................................................

/*
** Make an shallow copy of pFrom into pTo.  Prior contents of
** pTo are freed.  The pFrom->z field is not duplicated.  If
** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
** and flags gets srcType (either MEM_Ephem or MEM_Static).
*/





SQLITE_PRIVATE void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
  assert( (pFrom->flags & MEM_RowSet)==0 );
  assert( pTo->db==pFrom->db );
  if( VdbeMemDynamic(pTo) ) vdbeMemClearExternAndSetNull(pTo);
  memcpy(pTo, pFrom, MEMCELLSIZE);
  if( (pFrom->flags&MEM_Static)==0 ){
    pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
    assert( srcType==MEM_Ephem || srcType==MEM_Static );
    pTo->flags |= srcType;
  }
}
................................................................................
** pMem->zMalloc space will be allocated if necessary.  The calling routine
** is responsible for making sure that the pMem object is eventually
** destroyed.
**
** If this routine fails for any reason (malloc returns NULL or unable
** to read from the disk) then the pMem is left in an inconsistent state.
*/


























SQLITE_PRIVATE int sqlite3VdbeMemFromBtree(
  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
  u32 offset,       /* Offset from the start of data to return bytes from. */
  u32 amt,          /* Number of bytes to return. */
  int key,          /* If true, retrieve from the btree key, not data. */
  Mem *pMem         /* OUT: Return data in this Mem structure. */
){
................................................................................
  assert( zData!=0 );

  if( offset+amt<=available ){
    pMem->z = &zData[offset];
    pMem->flags = MEM_Blob|MEM_Ephem;
    pMem->n = (int)amt;
  }else{
    pMem->flags = MEM_Null;
    if( SQLITE_OK==(rc = sqlite3VdbeMemClearAndResize(pMem, amt+2)) ){
      if( key ){
        rc = sqlite3BtreeKey(pCur, offset, amt, pMem->z);
      }else{
        rc = sqlite3BtreeData(pCur, offset, amt, pMem->z);
      }
      if( rc==SQLITE_OK ){
        pMem->z[amt] = 0;
        pMem->z[amt+1] = 0;
        pMem->flags = MEM_Blob|MEM_Term;
        pMem->n = (int)amt;
      }else{
        sqlite3VdbeMemRelease(pMem);
      }
    }
  }

  return rc;
}

/*
** The pVal argument is known to be a value other than NULL.
................................................................................
    if( ExprHasProperty(pExpr, EP_IntValue) ){
      sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
    }else{
      zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
      if( zVal==0 ) goto no_mem;
      sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
    }
    if( (op==TK_INTEGER || op==TK_FLOAT ) && affinity==SQLITE_AFF_NONE ){
      sqlite3ValueApplyAffinity(pVal, SQLITE_AFF_NUMERIC, SQLITE_UTF8);
    }else{
      sqlite3ValueApplyAffinity(pVal, affinity, SQLITE_UTF8);
    }
    if( pVal->flags & (MEM_Int|MEM_Real) ) pVal->flags &= ~MEM_Str;
    if( enc!=SQLITE_UTF8 ){
      rc = sqlite3VdbeChangeEncoding(pVal, enc);
................................................................................
SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value *v){
  if( !v ) return;
  sqlite3VdbeMemRelease((Mem *)v);
  sqlite3DbFree(((Mem*)v)->db, v);
}

/*
** Return the number of bytes in the sqlite3_value object assuming
** that it uses the encoding "enc"

*/



SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value *pVal, u8 enc){
  Mem *p = (Mem*)pVal;




  if( (p->flags & MEM_Blob)!=0 || sqlite3ValueText(pVal, enc) ){
    if( p->flags & MEM_Zero ){
      return p->n + p->u.nZero;
    }else{
      return p->n;
    }
  }
  return 0;

}

/************** End of vdbemem.c *********************************************/
/************** Begin file vdbeaux.c *****************************************/
/*
** 2003 September 6
**
................................................................................
  const char *zP4,    /* The P4 operand */
  int p4type          /* P4 operand type */
){
  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
  sqlite3VdbeChangeP4(p, addr, zP4, p4type);
  return addr;
}


















/*
** Add an OP_ParseSchema opcode.  This routine is broken out from
** sqlite3VdbeAddOp4() since it needs to also needs to mark all btrees
** as having been used.
**
** The zWhere string must have been obtained from sqlite3_malloc().
................................................................................
**
**   *  OP_Halt with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
**   *  OP_HaltIfNull with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
**   *  OP_Destroy
**   *  OP_VUpdate
**   *  OP_VRename
**   *  OP_FkCounter with P2==0 (immediate foreign key constraint)

**
** Then check that the value of Parse.mayAbort is true if an
** ABORT may be thrown, or false otherwise. Return true if it does
** match, or false otherwise. This function is intended to be used as
** part of an assert statement in the compiler. Similar to:
**
**   assert( sqlite3VdbeAssertMayAbort(pParse->pVdbe, pParse->mayAbort) );
*/
SQLITE_PRIVATE int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
  int hasAbort = 0;
  int hasFkCounter = 0;


  Op *pOp;
  VdbeOpIter sIter;
  memset(&sIter, 0, sizeof(sIter));
  sIter.v = v;

  while( (pOp = opIterNext(&sIter))!=0 ){
    int opcode = pOp->opcode;
................................................................................
    if( opcode==OP_Destroy || opcode==OP_VUpdate || opcode==OP_VRename 
     || ((opcode==OP_Halt || opcode==OP_HaltIfNull) 
      && ((pOp->p1&0xff)==SQLITE_CONSTRAINT && pOp->p2==OE_Abort))
    ){
      hasAbort = 1;
      break;
    }


#ifndef SQLITE_OMIT_FOREIGN_KEY
    if( opcode==OP_FkCounter && pOp->p1==0 && pOp->p2==1 ){
      hasFkCounter = 1;
    }
#endif
  }
  sqlite3DbFree(v->db, sIter.apSub);

  /* Return true if hasAbort==mayAbort. Or if a malloc failure occurred.
  ** If malloc failed, then the while() loop above may not have iterated
  ** through all opcodes and hasAbort may be set incorrectly. Return
  ** true for this case to prevent the assert() in the callers frame
  ** from failing.  */
  return ( v->db->mallocFailed || hasAbort==mayAbort || hasFkCounter );

}
#endif /* SQLITE_DEBUG - the sqlite3AssertMayAbort() function */

/*
** Loop through the program looking for P2 values that are negative
** on jump instructions.  Each such value is a label.  Resolve the
** label by setting the P2 value to its correct non-zero value.
................................................................................
}
#endif

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
/*
** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter().
*/
SQLITE_PRIVATE void sqlite3VdbeLeave(Vdbe *p){
  int i;
  sqlite3 *db;
  Db *aDb;
  int nDb;
  if( DbMaskAllZero(p->lockMask) ) return;  /* The common case */
  db = p->db;
  aDb = db->aDb;
  nDb = db->nDb;
  for(i=0; i<nDb; i++){
    if( i!=1 && DbMaskTest(p->lockMask,i) && ALWAYS(aDb[i].pBt!=0) ){
      sqlite3BtreeLeave(aDb[i].pBt);
    }
  }




}
#endif

#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
/*
** Print a single opcode.  This routine is used for debugging only.
*/
................................................................................
**    is not possible.  Note that the integer representation is
**    always preferred, even if the affinity is REAL, because
**    an integer representation is more space efficient on disk.
**
** SQLITE_AFF_TEXT:
**    Convert pRec to a text representation.
**
** SQLITE_AFF_NONE:
**    No-op.  pRec is unchanged.
*/
static void applyAffinity(
  Mem *pRec,          /* The value to apply affinity to */
  char affinity,      /* The affinity to be applied */
  u8 enc              /* Use this text encoding */
){
................................................................................
  assert( p->explain==0 );
  p->pResultSet = 0;
  db->busyHandler.nBusy = 0;
  if( db->u1.isInterrupted ) goto abort_due_to_interrupt;
  sqlite3VdbeIOTraceSql(p);
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  if( db->xProgress ){

    assert( 0 < db->nProgressOps );
    nProgressLimit = (unsigned)p->aCounter[SQLITE_STMTSTATUS_VM_STEP];
    if( nProgressLimit==0 ){
      nProgressLimit = db->nProgressOps;
    }else{
      nProgressLimit %= (unsigned)db->nProgressOps;
    }
  }
#endif
#ifdef SQLITE_DEBUG
  sqlite3BeginBenignMalloc();
  if( p->pc==0
   && (p->db->flags & (SQLITE_VdbeListing|SQLITE_VdbeEQP|SQLITE_VdbeTrace))!=0
  ){
................................................................................
** <li value="100"> INTEGER
** <li value="101"> REAL
** </ul>
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_Cast: {                  /* in1 */
  assert( pOp->p2>=SQLITE_AFF_NONE && pOp->p2<=SQLITE_AFF_REAL );
  testcase( pOp->p2==SQLITE_AFF_TEXT );
  testcase( pOp->p2==SQLITE_AFF_NONE );
  testcase( pOp->p2==SQLITE_AFF_NUMERIC );
  testcase( pOp->p2==SQLITE_AFF_INTEGER );
  testcase( pOp->p2==SQLITE_AFF_REAL );
  pIn1 = &aMem[pOp->p1];
  memAboutToChange(p, pIn1);
  rc = ExpandBlob(pIn1);
  sqlite3VdbeMemCast(pIn1, pOp->p2, encoding);
................................................................................
** P4 may be a string that is P2 characters long.  The nth character of the
** string indicates the column affinity that should be used for the nth
** field of the index key.
**
** The mapping from character to affinity is given by the SQLITE_AFF_
** macros defined in sqliteInt.h.
**
** If P4 is NULL then all index fields have the affinity NONE.
*/
case OP_MakeRecord: {
  u8 *zNewRecord;        /* A buffer to hold the data for the new record */
  Mem *pRec;             /* The new record */
  u64 nData;             /* Number of bytes of data space */
  int nHdr;              /* Number of bytes of header space */
  i64 nByte;             /* Data space required for this record */
................................................................................
*/
case OP_Close: {
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  sqlite3VdbeFreeCursor(p, p->apCsr[pOp->p1]);
  p->apCsr[pOp->p1] = 0;
  break;
}





















/* Opcode: SeekGE P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as the key.  If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
................................................................................
        if( ExprHasProperty(pItem->pExpr, EP_Agg) ){
          sqlite3ErrorMsg(pParse, "aggregate functions are not allowed in "
              "the GROUP BY clause");
          return WRC_Abort;
        }
      }
    }








    /* Advance to the next term of the compound
    */
    p = p->pPrior;
    nCompound++;
  }

................................................................................
  if( aff1 && aff2 ){
    /* Both sides of the comparison are columns. If one has numeric
    ** affinity, use that. Otherwise use no affinity.
    */
    if( sqlite3IsNumericAffinity(aff1) || sqlite3IsNumericAffinity(aff2) ){
      return SQLITE_AFF_NUMERIC;
    }else{
      return SQLITE_AFF_NONE;
    }
  }else if( !aff1 && !aff2 ){
    /* Neither side of the comparison is a column.  Compare the
    ** results directly.
    */
    return SQLITE_AFF_NONE;
  }else{
    /* One side is a column, the other is not. Use the columns affinity. */
    assert( aff1==0 || aff2==0 );
    return (aff1 + aff2);
  }
}

................................................................................
  assert( pExpr->pLeft );
  aff = sqlite3ExprAffinity(pExpr->pLeft);
  if( pExpr->pRight ){
    aff = sqlite3CompareAffinity(pExpr->pRight, aff);
  }else if( ExprHasProperty(pExpr, EP_xIsSelect) ){
    aff = sqlite3CompareAffinity(pExpr->x.pSelect->pEList->a[0].pExpr, aff);
  }else if( !aff ){
    aff = SQLITE_AFF_NONE;
  }
  return aff;
}

/*
** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.
** idx_affinity is the affinity of an indexed column. Return true
** if the index with affinity idx_affinity may be used to implement
** the comparison in pExpr.
*/
SQLITE_PRIVATE int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity){
  char aff = comparisonAffinity(pExpr);
  switch( aff ){
    case SQLITE_AFF_NONE:
      return 1;
    case SQLITE_AFF_TEXT:
      return idx_affinity==SQLITE_AFF_TEXT;
    default:
      return sqlite3IsNumericAffinity(idx_affinity);
  }
}
................................................................................
    pNewItem->jointype = pOldItem->jointype;
    pNewItem->iCursor = pOldItem->iCursor;
    pNewItem->addrFillSub = pOldItem->addrFillSub;
    pNewItem->regReturn = pOldItem->regReturn;
    pNewItem->isCorrelated = pOldItem->isCorrelated;
    pNewItem->viaCoroutine = pOldItem->viaCoroutine;
    pNewItem->isRecursive = pOldItem->isRecursive;
    pNewItem->zIndex = sqlite3DbStrDup(db, pOldItem->zIndex);
    pNewItem->notIndexed = pOldItem->notIndexed;
    pNewItem->pIndex = pOldItem->pIndex;
    pTab = pNewItem->pTab = pOldItem->pTab;
    if( pTab ){
      pTab->nRef++;
    }
    pNewItem->pSelect = sqlite3SelectDup(db, pOldItem->pSelect, flags);
................................................................................
** Walker.eCode value determines the type of "constant" we are looking
** for.
**
** These callback routines are used to implement the following:
**
**     sqlite3ExprIsConstant()                  pWalker->eCode==1
**     sqlite3ExprIsConstantNotJoin()           pWalker->eCode==2
**     sqlite3ExprRefOneTableOnly()             pWalker->eCode==3
**     sqlite3ExprIsConstantOrFunction()        pWalker->eCode==4 or 5
**
** In all cases, the callbacks set Walker.eCode=0 and abort if the expression
** is found to not be a constant.
**
** The sqlite3ExprIsConstantOrFunction() is used for evaluating expressions
** in a CREATE TABLE statement.  The Walker.eCode value is 5 when parsing
................................................................................
** an ON or USING clause.
*/
SQLITE_PRIVATE int sqlite3ExprIsConstantNotJoin(Expr *p){
  return exprIsConst(p, 2, 0);
}

/*
** Walk an expression tree.  Return non-zero if the expression constant
** for any single row of the table with cursor iCur.  In other words, the
** expression must not refer to any non-deterministic function nor any
** table other than iCur.
*/
SQLITE_PRIVATE int sqlite3ExprIsTableConstant(Expr *p, int iCur){
  return exprIsConst(p, 3, iCur);
}
................................................................................
** This routine is used to determine if the OP_Affinity operation
** can be omitted.  When in doubt return FALSE.  A false negative
** is harmless.  A false positive, however, can result in the wrong
** answer.
*/
SQLITE_PRIVATE int sqlite3ExprNeedsNoAffinityChange(const Expr *p, char aff){
  u8 op;
  if( aff==SQLITE_AFF_NONE ) return 1;
  while( p->op==TK_UPLUS || p->op==TK_UMINUS ){ p = p->pLeft; }
  op = p->op;
  if( op==TK_REGISTER ) op = p->op2;
  switch( op ){
    case TK_INTEGER: {
      return aff==SQLITE_AFF_INTEGER || aff==SQLITE_AFF_NUMERIC;
    }
................................................................................
        */
        int i;
        ExprList *pList = pExpr->x.pList;
        struct ExprList_item *pItem;
        int r1, r2, r3;

        if( !affinity ){
          affinity = SQLITE_AFF_NONE;
        }
        if( pKeyInfo ){
          assert( sqlite3KeyInfoIsWriteable(pKeyInfo) );
          pKeyInfo->aColl[0] = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
        }

        /* Loop through each expression in <exprlist>. */
................................................................................
  }
  sqlite3ReleaseTempReg(pParse, r1);
  sqlite3ExprCachePop(pParse);
  VdbeComment((v, "end IN expr"));
}
#endif /* SQLITE_OMIT_SUBQUERY */

/*
** Duplicate an 8-byte value
*/
static char *dup8bytes(Vdbe *v, const char *in){
  char *out = sqlite3DbMallocRaw(sqlite3VdbeDb(v), 8);
  if( out ){
    memcpy(out, in, 8);
  }
  return out;
}

#ifndef SQLITE_OMIT_FLOATING_POINT
/*
** Generate an instruction that will put the floating point
** value described by z[0..n-1] into register iMem.
**
** The z[] string will probably not be zero-terminated.  But the 
** z[n] character is guaranteed to be something that does not look
** like the continuation of the number.
*/
static void codeReal(Vdbe *v, const char *z, int negateFlag, int iMem){
  if( ALWAYS(z!=0) ){
    double value;
    char *zV;
    sqlite3AtoF(z, &value, sqlite3Strlen30(z), SQLITE_UTF8);
    assert( !sqlite3IsNaN(value) ); /* The new AtoF never returns NaN */
    if( negateFlag ) value = -value;
    zV = dup8bytes(v, (char*)&value);
    sqlite3VdbeAddOp4(v, OP_Real, 0, iMem, 0, zV, P4_REAL);
  }
}
#endif


/*
** Generate an instruction that will put the integer describe by
................................................................................
  }else{
    int c;
    i64 value;
    const char *z = pExpr->u.zToken;
    assert( z!=0 );
    c = sqlite3DecOrHexToI64(z, &value);
    if( c==0 || (c==2 && negFlag) ){
      char *zV;
      if( negFlag ){ value = c==2 ? SMALLEST_INT64 : -value; }
      zV = dup8bytes(v, (char*)&value);
      sqlite3VdbeAddOp4(v, OP_Int64, 0, iMem, 0, zV, P4_INT64);
    }else{
#ifdef SQLITE_OMIT_FLOATING_POINT
      sqlite3ErrorMsg(pParse, "oversized integer: %s%s", negFlag ? "-" : "", z);
#else
#ifndef SQLITE_OMIT_HEX_INTEGER
      if( sqlite3_strnicmp(z,"0x",2)==0 ){
        sqlite3ErrorMsg(pParse, "hex literal too big: %s", z);
................................................................................
      }

      /* The UNLIKELY() function is a no-op.  The result is the value
      ** of the first argument.
      */
      if( pDef->funcFlags & SQLITE_FUNC_UNLIKELY ){
        assert( nFarg>=1 );
        sqlite3ExprCode(pParse, pFarg->a[0].pExpr, target);
        break;
      }

      for(i=0; i<nFarg; i++){
        if( i<32 && sqlite3ExprIsConstant(pFarg->a[i].pExpr) ){
          testcase( i==31 );
          constMask |= MASKBIT32(i);
................................................................................
  assert( pExpr->op!=TK_REGISTER );
  sqlite3ExprCode(pParse, pExpr, target);
  iMem = ++pParse->nMem;
  sqlite3VdbeAddOp2(v, OP_Copy, target, iMem);
  exprToRegister(pExpr, iMem);
}

#ifdef SQLITE_DEBUG
/*
** Generate a human-readable explanation of an expression tree.
*/
SQLITE_PRIVATE void sqlite3TreeViewExpr(TreeView *pView, const Expr *pExpr, u8 moreToFollow){
  const char *zBinOp = 0;   /* Binary operator */
  const char *zUniOp = 0;   /* Unary operator */
  pView = sqlite3TreeViewPush(pView, moreToFollow);
  if( pExpr==0 ){
    sqlite3TreeViewLine(pView, "nil");
    sqlite3TreeViewPop(pView);
    return;
  }
  switch( pExpr->op ){
    case TK_AGG_COLUMN: {
      sqlite3TreeViewLine(pView, "AGG{%d:%d}",
            pExpr->iTable, pExpr->iColumn);
      break;
    }
    case TK_COLUMN: {
      if( pExpr->iTable<0 ){
        /* This only happens when coding check constraints */
        sqlite3TreeViewLine(pView, "COLUMN(%d)", pExpr->iColumn);
      }else{
        sqlite3TreeViewLine(pView, "{%d:%d}",
                             pExpr->iTable, pExpr->iColumn);
      }
      break;
    }
    case TK_INTEGER: {
      if( pExpr->flags & EP_IntValue ){
        sqlite3TreeViewLine(pView, "%d", pExpr->u.iValue);
      }else{
        sqlite3TreeViewLine(pView, "%s", pExpr->u.zToken);
      }
      break;
    }
#ifndef SQLITE_OMIT_FLOATING_POINT
    case TK_FLOAT: {
      sqlite3TreeViewLine(pView,"%s", pExpr->u.zToken);
      break;
    }
#endif
    case TK_STRING: {
      sqlite3TreeViewLine(pView,"%Q", pExpr->u.zToken);
      break;
    }
    case TK_NULL: {
      sqlite3TreeViewLine(pView,"NULL");
      break;
    }
#ifndef SQLITE_OMIT_BLOB_LITERAL
    case TK_BLOB: {
      sqlite3TreeViewLine(pView,"%s", pExpr->u.zToken);
      break;
    }
#endif
    case TK_VARIABLE: {
      sqlite3TreeViewLine(pView,"VARIABLE(%s,%d)",
                          pExpr->u.zToken, pExpr->iColumn);
      break;
    }
    case TK_REGISTER: {
      sqlite3TreeViewLine(pView,"REGISTER(%d)", pExpr->iTable);
      break;
    }
    case TK_AS: {
      sqlite3TreeViewLine(pView,"AS %Q", pExpr->u.zToken);
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
      break;
    }
    case TK_ID: {
      sqlite3TreeViewLine(pView,"ID \"%w\"", pExpr->u.zToken);
      break;
    }
#ifndef SQLITE_OMIT_CAST
    case TK_CAST: {
      /* Expressions of the form:   CAST(pLeft AS token) */
      sqlite3TreeViewLine(pView,"CAST %Q", pExpr->u.zToken);
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
      break;
    }
#endif /* SQLITE_OMIT_CAST */
    case TK_LT:      zBinOp = "LT";     break;
    case TK_LE:      zBinOp = "LE";     break;
    case TK_GT:      zBinOp = "GT";     break;
    case TK_GE:      zBinOp = "GE";     break;
    case TK_NE:      zBinOp = "NE";     break;
    case TK_EQ:      zBinOp = "EQ";     break;
    case TK_IS:      zBinOp = "IS";     break;
    case TK_ISNOT:   zBinOp = "ISNOT";  break;
    case TK_AND:     zBinOp = "AND";    break;
    case TK_OR:      zBinOp = "OR";     break;
    case TK_PLUS:    zBinOp = "ADD";    break;
    case TK_STAR:    zBinOp = "MUL";    break;
    case TK_MINUS:   zBinOp = "SUB";    break;
    case TK_REM:     zBinOp = "REM";    break;
    case TK_BITAND:  zBinOp = "BITAND"; break;
    case TK_BITOR:   zBinOp = "BITOR";  break;
    case TK_SLASH:   zBinOp = "DIV";    break;
    case TK_LSHIFT:  zBinOp = "LSHIFT"; break;
    case TK_RSHIFT:  zBinOp = "RSHIFT"; break;
    case TK_CONCAT:  zBinOp = "CONCAT"; break;
    case TK_DOT:     zBinOp = "DOT";    break;

    case TK_UMINUS:  zUniOp = "UMINUS"; break;
    case TK_UPLUS:   zUniOp = "UPLUS";  break;
    case TK_BITNOT:  zUniOp = "BITNOT"; break;
    case TK_NOT:     zUniOp = "NOT";    break;
    case TK_ISNULL:  zUniOp = "ISNULL"; break;
    case TK_NOTNULL: zUniOp = "NOTNULL"; break;

    case TK_COLLATE: {
      sqlite3TreeViewLine(pView, "COLLATE %Q", pExpr->u.zToken);
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
      break;
    }

    case TK_AGG_FUNCTION:
    case TK_FUNCTION: {
      ExprList *pFarg;       /* List of function arguments */
      if( ExprHasProperty(pExpr, EP_TokenOnly) ){
        pFarg = 0;
      }else{
        pFarg = pExpr->x.pList;
      }
      if( pExpr->op==TK_AGG_FUNCTION ){
        sqlite3TreeViewLine(pView, "AGG_FUNCTION%d %Q",
                             pExpr->op2, pExpr->u.zToken);
      }else{
        sqlite3TreeViewLine(pView, "FUNCTION %Q", pExpr->u.zToken);
      }
      if( pFarg ){
        sqlite3TreeViewExprList(pView, pFarg, 0, 0);
      }
      break;
    }
#ifndef SQLITE_OMIT_SUBQUERY
    case TK_EXISTS: {
      sqlite3TreeViewLine(pView, "EXISTS-expr");
      sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
      break;
    }
    case TK_SELECT: {
      sqlite3TreeViewLine(pView, "SELECT-expr");
      sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
      break;
    }
    case TK_IN: {
      sqlite3TreeViewLine(pView, "IN");
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
        sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
      }else{
        sqlite3TreeViewExprList(pView, pExpr->x.pList, 0, 0);
      }
      break;
    }
#endif /* SQLITE_OMIT_SUBQUERY */

    /*
    **    x BETWEEN y AND z
    **
    ** This is equivalent to
    **
    **    x>=y AND x<=z
    **
    ** X is stored in pExpr->pLeft.
    ** Y is stored in pExpr->pList->a[0].pExpr.
    ** Z is stored in pExpr->pList->a[1].pExpr.
    */
    case TK_BETWEEN: {
      Expr *pX = pExpr->pLeft;
      Expr *pY = pExpr->x.pList->a[0].pExpr;
      Expr *pZ = pExpr->x.pList->a[1].pExpr;
      sqlite3TreeViewLine(pView, "BETWEEN");
      sqlite3TreeViewExpr(pView, pX, 1);
      sqlite3TreeViewExpr(pView, pY, 1);
      sqlite3TreeViewExpr(pView, pZ, 0);
      break;
    }
    case TK_TRIGGER: {
      /* If the opcode is TK_TRIGGER, then the expression is a reference
      ** to a column in the new.* or old.* pseudo-tables available to
      ** trigger programs. In this case Expr.iTable is set to 1 for the
      ** new.* pseudo-table, or 0 for the old.* pseudo-table. Expr.iColumn
      ** is set to the column of the pseudo-table to read, or to -1 to
      ** read the rowid field.
      */
      sqlite3TreeViewLine(pView, "%s(%d)", 
          pExpr->iTable ? "NEW" : "OLD", pExpr->iColumn);
      break;
    }
    case TK_CASE: {
      sqlite3TreeViewLine(pView, "CASE");
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
      sqlite3TreeViewExprList(pView, pExpr->x.pList, 0, 0);
      break;
    }
#ifndef SQLITE_OMIT_TRIGGER
    case TK_RAISE: {
      const char *zType = "unk";
      switch( pExpr->affinity ){
        case OE_Rollback:   zType = "rollback";  break;
        case OE_Abort:      zType = "abort";     break;
        case OE_Fail:       zType = "fail";      break;
        case OE_Ignore:     zType = "ignore";    break;
      }
      sqlite3TreeViewLine(pView, "RAISE %s(%Q)", zType, pExpr->u.zToken);
      break;
    }
#endif
    default: {
      sqlite3TreeViewLine(pView, "op=%d", pExpr->op);
      break;
    }
  }
  if( zBinOp ){
    sqlite3TreeViewLine(pView, "%s", zBinOp);
    sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
    sqlite3TreeViewExpr(pView, pExpr->pRight, 0);
  }else if( zUniOp ){
    sqlite3TreeViewLine(pView, "%s", zUniOp);
    sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
  }
  sqlite3TreeViewPop(pView);
}
#endif /* SQLITE_DEBUG */

#ifdef SQLITE_DEBUG
/*
** Generate a human-readable explanation of an expression list.
*/
SQLITE_PRIVATE void sqlite3TreeViewExprList(
  TreeView *pView,
  const ExprList *pList,
  u8 moreToFollow,
  const char *zLabel
){
  int i;
  pView = sqlite3TreeViewPush(pView, moreToFollow);
  if( zLabel==0 || zLabel[0]==0 ) zLabel = "LIST";
  if( pList==0 ){
    sqlite3TreeViewLine(pView, "%s (empty)", zLabel);
  }else{
    sqlite3TreeViewLine(pView, "%s", zLabel);
    for(i=0; i<pList->nExpr; i++){
      sqlite3TreeViewExpr(pView, pList->a[i].pExpr, i<pList->nExpr-1);
#if 0
     if( pList->a[i].zName ){
        sqlite3ExplainPrintf(pOut, " AS %s", pList->a[i].zName);
      }
      if( pList->a[i].bSpanIsTab ){
        sqlite3ExplainPrintf(pOut, " (%s)", pList->a[i].zSpan);
      }
#endif
    }
  }
  sqlite3TreeViewPop(pView);
}
#endif /* SQLITE_DEBUG */

/*
** Generate code that pushes the value of every element of the given
** expression list into a sequence of registers beginning at target.
**
** Return the number of elements evaluated.
**
** The SQLITE_ECEL_DUP flag prevents the arguments from being
................................................................................
      }
      break;
    }
  }
  sqlite3ReleaseTempReg(pParse, regFree1);
  sqlite3ReleaseTempReg(pParse, regFree2);
}
















/*
** Do a deep comparison of two expression trees.  Return 0 if the two
** expressions are completely identical.  Return 1 if they differ only
** by a COLLATE operator at the top level.  Return 2 if there are differences
** other than the top-level COLLATE operator.
**
................................................................................

  /* Ensure the default expression is something that sqlite3ValueFromExpr()
  ** can handle (i.e. not CURRENT_TIME etc.)
  */
  if( pDflt ){
    sqlite3_value *pVal = 0;
    int rc;
    rc = sqlite3ValueFromExpr(db, pDflt, SQLITE_UTF8, SQLITE_AFF_NONE, &pVal);
    assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
    if( rc!=SQLITE_OK ){
      db->mallocFailed = 1;
      return;
    }
    if( !pVal ){
      sqlite3ErrorMsg(pParse, "Cannot add a column with non-constant default");
................................................................................
  ** indices.  Hence, the record number for the table must be allocated
  ** now.
  */
  if( !db->init.busy && (v = sqlite3GetVdbe(pParse))!=0 ){
    int j1;
    int fileFormat;
    int reg1, reg2, reg3;
    sqlite3BeginWriteOperation(pParse, 0, iDb);

#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( isVirtual ){
      sqlite3VdbeAddOp0(v, OP_VBegin);
    }
#endif

................................................................................
    p->aCol = aNew;
  }
  pCol = &p->aCol[p->nCol];
  memset(pCol, 0, sizeof(p->aCol[0]));
  pCol->zName = z;
 
  /* If there is no type specified, columns have the default affinity
  ** 'NONE'. If there is a type specified, then sqlite3AddColumnType() will
  ** be called next to set pCol->affinity correctly.
  */
  pCol->affinity = SQLITE_AFF_NONE;
  pCol->szEst = 1;
  p->nCol++;
}

/*
** This routine is called by the parser while in the middle of
** parsing a CREATE TABLE statement.  A "NOT NULL" constraint has
................................................................................
**
** Substring     | Affinity
** --------------------------------
** 'INT'         | SQLITE_AFF_INTEGER
** 'CHAR'        | SQLITE_AFF_TEXT
** 'CLOB'        | SQLITE_AFF_TEXT
** 'TEXT'        | SQLITE_AFF_TEXT
** 'BLOB'        | SQLITE_AFF_NONE
** 'REAL'        | SQLITE_AFF_REAL
** 'FLOA'        | SQLITE_AFF_REAL
** 'DOUB'        | SQLITE_AFF_REAL
**
** If none of the substrings in the above table are found,
** SQLITE_AFF_NUMERIC is returned.
*/
................................................................................
      zChar = zIn;
    }else if( h==(('c'<<24)+('l'<<16)+('o'<<8)+'b') ){       /* CLOB */
      aff = SQLITE_AFF_TEXT;
    }else if( h==(('t'<<24)+('e'<<16)+('x'<<8)+'t') ){       /* TEXT */
      aff = SQLITE_AFF_TEXT;
    }else if( h==(('b'<<24)+('l'<<16)+('o'<<8)+'b')          /* BLOB */
        && (aff==SQLITE_AFF_NUMERIC || aff==SQLITE_AFF_REAL) ){
      aff = SQLITE_AFF_NONE;
      if( zIn[0]=='(' ) zChar = zIn;
#ifndef SQLITE_OMIT_FLOATING_POINT
    }else if( h==(('r'<<24)+('e'<<16)+('a'<<8)+'l')          /* REAL */
        && aff==SQLITE_AFF_NUMERIC ){
      aff = SQLITE_AFF_REAL;
    }else if( h==(('f'<<24)+('l'<<16)+('o'<<8)+'a')          /* FLOA */
        && aff==SQLITE_AFF_NUMERIC ){
................................................................................
  }
  sqlite3_snprintf(n, zStmt, "CREATE TABLE ");
  k = sqlite3Strlen30(zStmt);
  identPut(zStmt, &k, p->zName);
  zStmt[k++] = '(';
  for(pCol=p->aCol, i=0; i<p->nCol; i++, pCol++){
    static const char * const azType[] = {
        /* SQLITE_AFF_NONE    */ "",
        /* SQLITE_AFF_TEXT    */ " TEXT",
        /* SQLITE_AFF_NUMERIC */ " NUM",
        /* SQLITE_AFF_INTEGER */ " INT",
        /* SQLITE_AFF_REAL    */ " REAL"
    };
    int len;
    const char *zType;

    sqlite3_snprintf(n-k, &zStmt[k], zSep);
    k += sqlite3Strlen30(&zStmt[k]);
    zSep = zSep2;
    identPut(zStmt, &k, pCol->zName);
    assert( pCol->affinity-SQLITE_AFF_NONE >= 0 );
    assert( pCol->affinity-SQLITE_AFF_NONE < ArraySize(azType) );
    testcase( pCol->affinity==SQLITE_AFF_NONE );
    testcase( pCol->affinity==SQLITE_AFF_TEXT );
    testcase( pCol->affinity==SQLITE_AFF_NUMERIC );
    testcase( pCol->affinity==SQLITE_AFF_INTEGER );
    testcase( pCol->affinity==SQLITE_AFF_REAL );
    
    zType = azType[pCol->affinity - SQLITE_AFF_NONE];
    len = sqlite3Strlen30(zType);
    assert( pCol->affinity==SQLITE_AFF_NONE 
            || pCol->affinity==sqlite3AffinityType(zType, 0) );
    memcpy(&zStmt[k], zType, len);
    k += len;
    assert( k<=n );
  }
  sqlite3_snprintf(n-k, &zStmt[k], "%s", zEnd);
  return zStmt;
................................................................................
      int addrInsLoop;    /* Top of the loop for inserting rows */
      Table *pSelTab;     /* A table that describes the SELECT results */

      regYield = ++pParse->nMem;
      regRec = ++pParse->nMem;
      regRowid = ++pParse->nMem;
      assert(pParse->nTab==1);

      sqlite3VdbeAddOp3(v, OP_OpenWrite, 1, pParse->regRoot, iDb);
      sqlite3VdbeChangeP5(v, OPFLAG_P2ISREG);
      pParse->nTab = 2;
      addrTop = sqlite3VdbeCurrentAddr(v) + 1;
      sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, addrTop);
      sqlite3SelectDestInit(&dest, SRT_Coroutine, regYield);
      sqlite3Select(pParse, pSelect, &dest);
................................................................................
  int i;
  struct SrcList_item *pItem;
  if( pList==0 ) return;
  for(pItem=pList->a, i=0; i<pList->nSrc; i++, pItem++){
    sqlite3DbFree(db, pItem->zDatabase);
    sqlite3DbFree(db, pItem->zName);
    sqlite3DbFree(db, pItem->zAlias);
    sqlite3DbFree(db, pItem->zIndex);
    sqlite3DeleteTable(db, pItem->pTab);
    sqlite3SelectDelete(db, pItem->pSelect);
    sqlite3ExprDelete(db, pItem->pOn);
    sqlite3IdListDelete(db, pItem->pUsing);
  }
  sqlite3DbFree(db, pList);
}
................................................................................
** Add an INDEXED BY or NOT INDEXED clause to the most recently added 
** element of the source-list passed as the second argument.
*/
SQLITE_PRIVATE void sqlite3SrcListIndexedBy(Parse *pParse, SrcList *p, Token *pIndexedBy){
  assert( pIndexedBy!=0 );
  if( p && ALWAYS(p->nSrc>0) ){
    struct SrcList_item *pItem = &p->a[p->nSrc-1];
    assert( pItem->notIndexed==0 && pItem->zIndex==0 );
    if( pIndexedBy->n==1 && !pIndexedBy->z ){
      /* A "NOT INDEXED" clause was supplied. See parse.y 
      ** construct "indexed_opt" for details. */
      pItem->notIndexed = 1;
    }else{
      pItem->zIndex = sqlite3NameFromToken(pParse->db, pIndexedBy);
    }
  }
}

/*
** When building up a FROM clause in the parser, the join operator
** is initially attached to the left operand.  But the code generator
................................................................................
  int nCol;

  if( piPartIdxLabel ){
    if( pIdx->pPartIdxWhere ){
      *piPartIdxLabel = sqlite3VdbeMakeLabel(v);
      pParse->iPartIdxTab = iDataCur;
      sqlite3ExprCachePush(pParse);
      sqlite3ExprIfFalse(pParse, pIdx->pPartIdxWhere, *piPartIdxLabel, 
                         SQLITE_JUMPIFNULL);
    }else{
      *piPartIdxLabel = 0;
    }
  }
  nCol = (prefixOnly && pIdx->uniqNotNull) ? pIdx->nKeyCol : pIdx->nColumn;
  regBase = sqlite3GetTempRange(pParse, nCol);
  if( pPrior && (regBase!=regPrior || pPrior->pPartIdxWhere) ) pPrior = 0;
................................................................................
  u8 matchOne;
  u8 matchSet;
  u8 noCase;
};

/*
** For LIKE and GLOB matching on EBCDIC machines, assume that every
** character is exactly one byte in size.  Also, all characters are
** able to participate in upper-case-to-lower-case mappings in EBCDIC
** whereas only characters less than 0x80 do in ASCII.
*/
#if defined(SQLITE_EBCDIC)
# define sqlite3Utf8Read(A)        (*((*A)++))
# define GlobUpperToLower(A)       A = sqlite3UpperToLower[A]
# define GlobUpperToLowerAscii(A)  A = sqlite3UpperToLower[A]
#else
# define GlobUpperToLower(A)       if( A<=0x7f ){ A = sqlite3UpperToLower[A]; }
# define GlobUpperToLowerAscii(A)  A = sqlite3UpperToLower[A]

#endif

static const struct compareInfo globInfo = { '*', '?', '[', 0 };
/* The correct SQL-92 behavior is for the LIKE operator to ignore
** case.  Thus  'a' LIKE 'A' would be true. */
static const struct compareInfo likeInfoNorm = { '%', '_',   0, 1 };
/* If SQLITE_CASE_SENSITIVE_LIKE is defined, then the LIKE operator
................................................................................
**      '%'       Matches any sequence of zero or more characters
**
***     '_'       Matches any one character
**
**      Ec        Where E is the "esc" character and c is any other
**                character, including '%', '_', and esc, match exactly c.
**
** The comments through this routine usually assume glob matching.
**
** This routine is usually quick, but can be N**2 in the worst case.
*/
static int patternCompare(
  const u8 *zPattern,              /* The glob pattern */
  const u8 *zString,               /* The string to compare against the glob */
  const struct compareInfo *pInfo, /* Information about how to do the compare */
................................................................................
  /* The GLOB operator does not have an ESCAPE clause.  And LIKE does not
  ** have the matchSet operator.  So we either have to look for one or
  ** the other, never both.  Hence the single variable matchOther is used
  ** to store the one we have to look for.
  */
  matchOther = esc ? esc : pInfo->matchSet;

  while( (c = sqlite3Utf8Read(&zPattern))!=0 ){
    if( c==matchAll ){  /* Match "*" */
      /* Skip over multiple "*" characters in the pattern.  If there
      ** are also "?" characters, skip those as well, but consume a
      ** single character of the input string for each "?" skipped */
      while( (c=sqlite3Utf8Read(&zPattern)) == matchAll
               || c == matchOne ){
        if( c==matchOne && sqlite3Utf8Read(&zString)==0 ){
          return 0;
        }
      }
      if( c==0 ){
        return 1;   /* "*" at the end of the pattern matches */
      }else if( c==matchOther ){
................................................................................
          cx = c;
        }
        while( (c2 = *(zString++))!=0 ){
          if( c2!=c && c2!=cx ) continue;
          if( patternCompare(zPattern,zString,pInfo,esc) ) return 1;
        }
      }else{
        while( (c2 = sqlite3Utf8Read(&zString))!=0 ){
          if( c2!=c ) continue;
          if( patternCompare(zPattern,zString,pInfo,esc) ) return 1;
        }
      }
      return 0;
    }
    if( c==matchOther ){
................................................................................
        }
        if( c2==0 || (seen ^ invert)==0 ){
          return 0;
        }
        continue;
      }
    }
    c2 = sqlite3Utf8Read(&zString);
    if( c==c2 ) continue;
    if( noCase && c<0x80 && c2<0x80 && sqlite3Tolower(c)==sqlite3Tolower(c2) ){
      continue;
    }
    if( c==matchOne && zPattern!=zEscaped && c2!=0 ) continue;
    return 0;
  }
................................................................................
/*
** Return a pointer to the column affinity string associated with index
** pIdx. A column affinity string has one character for each column in 
** the table, according to the affinity of the column:
**
**  Character      Column affinity
**  ------------------------------
**  'A'            NONE
**  'B'            TEXT
**  'C'            NUMERIC
**  'D'            INTEGER
**  'F'            REAL
**
** An extra 'D' is appended to the end of the string to cover the
** rowid that appears as the last column in every index.
................................................................................
  }
 
  return pIdx->zColAff;
}

/*
** Compute the affinity string for table pTab, if it has not already been
** computed.  As an optimization, omit trailing SQLITE_AFF_NONE affinities.
**
** If the affinity exists (if it is no entirely SQLITE_AFF_NONE values) and
** if iReg>0 then code an OP_Affinity opcode that will set the affinities
** for register iReg and following.  Or if affinities exists and iReg==0,
** then just set the P4 operand of the previous opcode (which should  be
** an OP_MakeRecord) to the affinity string.
**
** A column affinity string has one character per column:
**
**  Character      Column affinity
**  ------------------------------
**  'A'            NONE
**  'B'            TEXT
**  'C'            NUMERIC
**  'D'            INTEGER
**  'E'            REAL
*/
SQLITE_PRIVATE void sqlite3TableAffinity(Vdbe *v, Table *pTab, int iReg){
  int i;
................................................................................
    }

    for(i=0; i<pTab->nCol; i++){
      zColAff[i] = pTab->aCol[i].affinity;
    }
    do{
      zColAff[i--] = 0;
    }while( i>=0 && zColAff[i]==SQLITE_AFF_NONE );
    pTab->zColAff = zColAff;
  }
  i = sqlite3Strlen30(zColAff);
  if( i ){
    if( iReg ){
      sqlite3VdbeAddOp4(v, OP_Affinity, iReg, i, 0, zColAff, i);
    }else{
................................................................................
    iThisCur = iIdxCur+ix;
    addrUniqueOk = sqlite3VdbeMakeLabel(v);

    /* Skip partial indices for which the WHERE clause is not true */
    if( pIdx->pPartIdxWhere ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, aRegIdx[ix]);
      pParse->ckBase = regNewData+1;
      sqlite3ExprIfFalse(pParse, pIdx->pPartIdxWhere, addrUniqueOk,
                         SQLITE_JUMPIFNULL);
      pParse->ckBase = 0;
    }

    /* Create a record for this index entry as it should appear after
    ** the insert or update.  Store that record in the aRegIdx[ix] register
    */
    regIdx = sqlite3GetTempRange(pParse, pIdx->nColumn);
................................................................................
  void *(*realloc64)(void*,sqlite3_uint64);
  void (*reset_auto_extension)(void);
  void (*result_blob64)(sqlite3_context*,const void*,sqlite3_uint64,
                        void(*)(void*));
  void (*result_text64)(sqlite3_context*,const char*,sqlite3_uint64,
                         void(*)(void*), unsigned char);
  int (*strglob)(const char*,const char*);

  sqlite3_value (*value_dup)(const sqlite3_value*);
  void (*value_free)(sqlite3_value*);
};

/*
** The following macros redefine the API routines so that they are
** redirected through the global sqlite3_api structure.
**
................................................................................
  sqlite3_load_extension,
  sqlite3_malloc64,
  sqlite3_msize,
  sqlite3_realloc64,
  sqlite3_reset_auto_extension,
  sqlite3_result_blob64,
  sqlite3_result_text64,
  sqlite3_strglob



};

/*
** Attempt to load an SQLite extension library contained in the file
** zFile.  The entry point is zProc.  zProc may be 0 in which case a
** default entry point name (sqlite3_extension_init) is used.  Use
** of the default name is recommended.
................................................................................
/*
** Trace output macros
*/
#if SELECTTRACE_ENABLED
/***/ int sqlite3SelectTrace = 0;
# define SELECTTRACE(K,P,S,X)  \
  if(sqlite3SelectTrace&(K))   \
    sqlite3DebugPrintf("%*s%s.%p: ",(P)->nSelectIndent*2-2,"",(S)->zSelName,(S)),\

    sqlite3DebugPrintf X
#else
# define SELECTTRACE(K,P,S,X)
#endif


/*
................................................................................
*/
static void setJoinExpr(Expr *p, int iTable){
  while( p ){
    ExprSetProperty(p, EP_FromJoin);
    assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
    ExprSetVVAProperty(p, EP_NoReduce);
    p->iRightJoinTable = (i16)iTable;






    setJoinExpr(p->pLeft, iTable);
    p = p->pRight;
  } 
}

/*
** This routine processes the join information for a SELECT statement.
................................................................................
      case WHERE_DISTINCT_UNIQUE: {
        sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
        break;
      }

      default: {
        assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED );
        codeDistinct(pParse, pDistinct->tabTnct, iContinue, nResultCol, regResult);

        break;
      }
    }
    if( pSort==0 ){
      codeOffset(v, p->iOffset, iContinue);
    }
  }
................................................................................
      if( eDest==SRT_DistFifo ){
        /* If the destination is DistFifo, then cursor (iParm+1) is open
        ** on an ephemeral index. If the current row is already present
        ** in the index, do not write it to the output. If not, add the
        ** current row to the index and proceed with writing it to the
        ** output table as well.  */
        int addr = sqlite3VdbeCurrentAddr(v) + 4;
        sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0); VdbeCoverage(v);

        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r1);
        assert( pSort==0 );
      }
#endif
      if( pSort ){
        pushOntoSorter(pParse, pSort, p, r1+nPrefixReg, 1, nPrefixReg);
      }else{
................................................................................
** The declaration type for any expression other than a column is NULL.
**
** This routine has either 3 or 6 parameters depending on whether or not
** the SQLITE_ENABLE_COLUMN_METADATA compile-time option is used.
*/
#ifdef SQLITE_ENABLE_COLUMN_METADATA
# define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,C,D,E,F)



static const char *columnTypeImpl(
  NameContext *pNC, 
  Expr *pExpr,

  const char **pzOrigDb,
  const char **pzOrigTab,
  const char **pzOrigCol,

  u8 *pEstWidth
){




  char const *zOrigDb = 0;
  char const *zOrigTab = 0;
  char const *zOrigCol = 0;
#else /* if !defined(SQLITE_ENABLE_COLUMN_METADATA) */
# define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,F)
static const char *columnTypeImpl(
  NameContext *pNC, 
  Expr *pExpr,
  u8 *pEstWidth
){
#endif /* !defined(SQLITE_ENABLE_COLUMN_METADATA) */
  char const *zType = 0;
  int j;
  u8 estWidth = 1;

  if( NEVER(pExpr==0) || pNC->pSrcList==0 ) return 0;
  switch( pExpr->op ){
    case TK_AGG_COLUMN:
    case TK_COLUMN: {
      /* The expression is a column. Locate the table the column is being
      ** extracted from in NameContext.pSrcList. This table may be real
................................................................................

      assert( pTab && pExpr->pTab==pTab );
      if( pS ){
        /* The "table" is actually a sub-select or a view in the FROM clause
        ** of the SELECT statement. Return the declaration type and origin
        ** data for the result-set column of the sub-select.
        */
        if( iCol>=0 && iCol<pS->pEList->nExpr ){
          /* If iCol is less than zero, then the expression requests the
          ** rowid of the sub-select or view. This expression is legal (see 
          ** test case misc2.2.2) - it always evaluates to NULL.



          */
          NameContext sNC;
          Expr *p = pS->pEList->a[iCol].pExpr;
          sNC.pSrcList = pS->pSrc;
          sNC.pNext = pNC;
          sNC.pParse = pNC->pParse;
          zType = columnType(&sNC, p,&zOrigDb,&zOrigTab,&zOrigCol, &estWidth); 
................................................................................
  if( db->mallocFailed ) return;
  memset(&sNC, 0, sizeof(sNC));
  sNC.pSrcList = pSelect->pSrc;
  a = pSelect->pEList->a;
  for(i=0, pCol=pTab->aCol; i<pTab->nCol; i++, pCol++){
    p = a[i].pExpr;
    if( pCol->zType==0 ){

      pCol->zType = sqlite3DbStrDup(db, columnType(&sNC, p,0,0,0, &pCol->szEst));
    }
    szAll += pCol->szEst;
    pCol->affinity = sqlite3ExprAffinity(p);
    if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_NONE;
    pColl = sqlite3ExprCollSeq(pParse, p);
    if( pColl && pCol->zColl==0 ){
      pCol->zColl = sqlite3DbStrDup(db, pColl->zName);
    }
  }
  pTab->szTabRow = sqlite3LogEst(szAll*4);
}
................................................................................
  CollSeq *pRet;
  if( p->pPrior ){
    pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
  }else{
    pRet = 0;
  }
  assert( iCol>=0 );



  if( pRet==0 && iCol<p->pEList->nExpr ){
    pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
  }
  return pRet;
}

/*
** The select statement passed as the second parameter is a compound SELECT
................................................................................
  SelectDest *pDest     /* What to do with query results */
);

/*
** Error message for when two or more terms of a compound select have different
** size result sets.
*/
static void selectWrongNumTermsError(Parse *pParse, Select *p){
  if( p->selFlags & SF_Values ){
    sqlite3ErrorMsg(pParse, "all VALUES must have the same number of terms");
  }else{
    sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
      " do not have the same number of result columns", selectOpName(p->op));
  }
}
................................................................................
*/
static int multiSelectValues(
  Parse *pParse,        /* Parsing context */
  Select *p,            /* The right-most of SELECTs to be coded */
  SelectDest *pDest     /* What to do with query results */
){
  Select *pPrior;
  int nExpr = p->pEList->nExpr;
  int nRow = 1;
  int rc = 0;
  assert( p->selFlags & SF_MultiValue );
  do{
    assert( p->selFlags & SF_Values );
    assert( p->op==TK_ALL || (p->op==TK_SELECT && p->pPrior==0) );
    assert( p->pLimit==0 );
    assert( p->pOffset==0 );
    if( p->pEList->nExpr!=nExpr ){
      selectWrongNumTermsError(pParse, p);
      return 1;
    }
    if( p->pPrior==0 ) break;
    assert( p->pPrior->pNext==p );
    p = p->pPrior;
    nRow++;
  }while(1);
  while( p ){
    pPrior = p->pPrior;
................................................................................
    goto multi_select_end;
  }

  /* Make sure all SELECTs in the statement have the same number of elements
  ** in their result sets.
  */
  assert( p->pEList && pPrior->pEList );
  if( p->pEList->nExpr!=pPrior->pEList->nExpr ){
    selectWrongNumTermsError(pParse, p);
    rc = 1;
    goto multi_select_end;
  }

#ifndef SQLITE_OMIT_CTE
  if( p->selFlags & SF_Recursive ){
    generateWithRecursiveQuery(pParse, p, &dest);
  }else
#endif

................................................................................
  ** collation.
  */
  aPermute = sqlite3DbMallocRaw(db, sizeof(int)*nOrderBy);
  if( aPermute ){
    struct ExprList_item *pItem;
    for(i=0, pItem=pOrderBy->a; i<nOrderBy; i++, pItem++){
      assert( pItem->u.x.iOrderByCol>0 );
      /* assert( pItem->u.x.iOrderByCol<=p->pEList->nExpr ) is also true
      ** but only for well-formed SELECT statements. */
      testcase( pItem->u.x.iOrderByCol > p->pEList->nExpr );
      aPermute[i] = pItem->u.x.iOrderByCol - 1;
    }
    pKeyMerge = multiSelectOrderByKeyInfo(pParse, p, 1);
  }else{
    pKeyMerge = 0;
  }

................................................................................
**   (8)  The subquery does not use LIMIT or the outer query is not a join.
**
**   (9)  The subquery does not use LIMIT or the outer query does not use
**        aggregates.
**
**  (**)  Restriction (10) was removed from the code on 2005-02-05 but we
**        accidently carried the comment forward until 2014-09-15.  Original
**        text: "The subquery does not use aggregates or the outer query does not
**        use LIMIT."
**
**  (11)  The subquery and the outer query do not both have ORDER BY clauses.
**
**  (**)  Not implemented.  Subsumed into restriction (3).  Was previously
**        a separate restriction deriving from ticket #350.
**
**  (13)  The subquery and outer query do not both use LIMIT.
................................................................................
    if( isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){
      return 0;
    }
    for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
      testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
      testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
      assert( pSub->pSrc!=0 );

      if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0
       || (pSub1->pPrior && pSub1->op!=TK_ALL) 
       || pSub1->pSrc->nSrc<1
       || pSub->pEList->nExpr!=pSub1->pEList->nExpr
      ){
        return 0;
      }
      testcase( pSub1->pSrc->nSrc>1 );
    }

    /* Restriction 18. */
................................................................................
  /* Finially, delete what is left of the subquery and return
  ** success.
  */
  sqlite3SelectDelete(db, pSub1);

#if SELECTTRACE_ENABLED
  if( sqlite3SelectTrace & 0x100 ){
    sqlite3DebugPrintf("After flattening:\n");
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif

  return 1;



































































}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */

/*
** Based on the contents of the AggInfo structure indicated by the first
** argument, this function checks if the following are true:
**
................................................................................
** If the source-list item passed as an argument was augmented with an
** INDEXED BY clause, then try to locate the specified index. If there
** was such a clause and the named index cannot be found, return 
** SQLITE_ERROR and leave an error in pParse. Otherwise, populate 
** pFrom->pIndex and return SQLITE_OK.
*/
SQLITE_PRIVATE int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){
  if( pFrom->pTab && pFrom->zIndex ){
    Table *pTab = pFrom->pTab;
    char *zIndex = pFrom->zIndex;
    Index *pIdx;
    for(pIdx=pTab->pIndex; 
        pIdx && sqlite3StrICmp(pIdx->zName, zIndex); 
        pIdx=pIdx->pNext
    );
    if( !pIdx ){
      sqlite3ErrorMsg(pParse, "no such index: %s", zIndex, 0);
      pParse->checkSchema = 1;
      return SQLITE_ERROR;
    }
    pFrom->pIndex = pIdx;
  }
  return SQLITE_OK;
}
................................................................................
    p->pOrderBy = 0;
    p->selFlags &= ~SF_Distinct;
  }
  sqlite3SelectPrep(pParse, p, 0);
  memset(&sSort, 0, sizeof(sSort));
  sSort.pOrderBy = p->pOrderBy;
  pTabList = p->pSrc;
  pEList = p->pEList;
  if( pParse->nErr || db->mallocFailed ){
    goto select_end;
  }

  isAgg = (p->selFlags & SF_Aggregate)!=0;
  assert( pEList!=0 );
#if SELECTTRACE_ENABLED
  if( sqlite3SelectTrace & 0x100 ){
    SELECTTRACE(0x100,pParse,p, ("after name resolution:\n"));
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif


  /* Begin generating code.
  */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto select_end;

  /* If writing to memory or generating a set
  ** only a single column may be output.
  */
#ifndef SQLITE_OMIT_SUBQUERY
  if( checkForMultiColumnSelectError(pParse, pDest, pEList->nExpr) ){
    goto select_end;
  }
#endif














































  /* Generate code for all sub-queries in the FROM clause
  */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
  for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
    struct SrcList_item *pItem = &pTabList->a[i];
    SelectDest dest;
    Select *pSub = pItem->pSelect;
    int isAggSub;

    if( pSub==0 ) continue;

    /* Sometimes the code for a subquery will be generated more than
    ** once, if the subquery is part of the WHERE clause in a LEFT JOIN,
    ** for example.  In that case, do not regenerate the code to manifest
    ** a view or the co-routine to implement a view.  The first instance
    ** is sufficient, though the subroutine to manifest the view does need
................................................................................
    ** may contain expression trees of at most
    ** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
    ** more conservative than necessary, but much easier than enforcing
    ** an exact limit.
    */
    pParse->nHeight += sqlite3SelectExprHeight(p);

    isAggSub = (pSub->selFlags & SF_Aggregate)!=0;
    if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){
      /* This subquery can be absorbed into its parent. */
      if( isAggSub ){
        isAgg = 1;
        p->selFlags |= SF_Aggregate;





      }
      i = -1;





    }else if( pTabList->nSrc==1
           && (p->selFlags & SF_All)==0
           && OptimizationEnabled(db, SQLITE_SubqCoroutine)
    ){
      /* Implement a co-routine that will return a single row of the result
      ** set on each invocation.
      */
      int addrTop = sqlite3VdbeCurrentAddr(v)+1;
      pItem->regReturn = ++pParse->nMem;
      sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
................................................................................
      pItem->pTab->nRowLogEst = sqlite3LogEst(pSub->nSelectRow);
      if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
      retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
      VdbeComment((v, "end %s", pItem->pTab->zName));
      sqlite3VdbeChangeP1(v, topAddr, retAddr);
      sqlite3ClearTempRegCache(pParse);
    }
    if( /*pParse->nErr ||*/ db->mallocFailed ){
      goto select_end;
    }
    pParse->nHeight -= sqlite3SelectExprHeight(p);
    pTabList = p->pSrc;
    if( !IgnorableOrderby(pDest) ){
      sSort.pOrderBy = p->pOrderBy;
    }

  }


  pEList = p->pEList;
#endif
  pWhere = p->pWhere;
  pGroupBy = p->pGroupBy;
  pHaving = p->pHaving;
  sDistinct.isTnct = (p->selFlags & SF_Distinct)!=0;

#ifndef SQLITE_OMIT_COMPOUND_SELECT
  /* If there is are a sequence of queries, do the earlier ones first.
  */
  if( p->pPrior ){
    rc = multiSelect(pParse, p, pDest);
    explainSetInteger(pParse->iSelectId, iRestoreSelectId);
#if SELECTTRACE_ENABLED
    SELECTTRACE(1,pParse,p,("end compound-select processing\n"));
    pParse->nSelectIndent--;
#endif
    return rc;



  }
#endif

  /* If the query is DISTINCT with an ORDER BY but is not an aggregate, and 
  ** if the select-list is the same as the ORDER BY list, then this query
  ** can be rewritten as a GROUP BY. In other words, this:
  **
................................................................................
  **
  ** The second form is preferred as a single index (or temp-table) may be 
  ** used for both the ORDER BY and DISTINCT processing. As originally 
  ** written the query must use a temp-table for at least one of the ORDER 
  ** BY and DISTINCT, and an index or separate temp-table for the other.
  */
  if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct 
   && sqlite3ExprListCompare(sSort.pOrderBy, p->pEList, -1)==0
  ){
    p->selFlags &= ~SF_Distinct;
    p->pGroupBy = sqlite3ExprListDup(db, p->pEList, 0);
    pGroupBy = p->pGroupBy;
    /* Notice that even thought SF_Distinct has been cleared from p->selFlags,
    ** the sDistinct.isTnct is still set.  Hence, isTnct represents the
    ** original setting of the SF_Distinct flag, not the current setting */
    assert( sDistinct.isTnct );
  }

  /* If there is an ORDER BY clause, then this sorting
  ** index might end up being unused if the data can be 
  ** extracted in pre-sorted order.  If that is the case, then the
  ** OP_OpenEphemeral instruction will be changed to an OP_Noop once
  ** we figure out that the sorting index is not needed.  The addrSortIndex
  ** variable is used to facilitate that change.

  */
  if( sSort.pOrderBy ){
    KeyInfo *pKeyInfo;
    pKeyInfo = keyInfoFromExprList(pParse, sSort.pOrderBy, 0, pEList->nExpr);
    sSort.iECursor = pParse->nTab++;
    sSort.addrSortIndex =
      sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
................................................................................
  p->nSelectRow = LARGEST_INT64;
  computeLimitRegisters(pParse, p, iEnd);
  if( p->iLimit==0 && sSort.addrSortIndex>=0 ){
    sqlite3VdbeGetOp(v, sSort.addrSortIndex)->opcode = OP_SorterOpen;
    sSort.sortFlags |= SORTFLAG_UseSorter;
  }

  /* Open a virtual index to use for the distinct set.
  */
  if( p->selFlags & SF_Distinct ){
    sDistinct.tabTnct = pParse->nTab++;
    sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
                                sDistinct.tabTnct, 0, 0,
                                (char*)keyInfoFromExprList(pParse, p->pEList,0,0),
                                P4_KEYINFO);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
    sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
  }else{
    sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
  }

  if( !isAgg && pGroupBy==0 ){
................................................................................
        pItem->u.x.iAlias = 0;
      }
      if( p->nSelectRow>100 ) p->nSelectRow = 100;
    }else{
      p->nSelectRow = 1;
    }


    /* If there is both a GROUP BY and an ORDER BY clause and they are
    ** identical, then it may be possible to disable the ORDER BY clause 
    ** on the grounds that the GROUP BY will cause elements to come out 
    ** in the correct order. It also may not - the GROUP BY may use a
    ** database index that causes rows to be grouped together as required
    ** but not actually sorted. Either way, record the fact that the
    ** ORDER BY and GROUP BY clauses are the same by setting the orderByGrp
    ** variable.  */
    if( sqlite3ExprListCompare(pGroupBy, sSort.pOrderBy, -1)==0 ){
      orderByGrp = 1;
    }
................................................................................
      ** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
      ** Then compare the current GROUP BY terms against the GROUP BY terms
      ** from the previous row currently stored in a0, a1, a2...
      */
      addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
      sqlite3ExprCacheClear(pParse);
      if( groupBySort ){
        sqlite3VdbeAddOp3(v, OP_SorterData, sAggInfo.sortingIdx, sortOut,sortPTab);

      }
      for(j=0; j<pGroupBy->nExpr; j++){
        if( groupBySort ){
          sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j);
        }else{
          sAggInfo.directMode = 1;
          sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j);
................................................................................
      */
      addrSetAbort = sqlite3VdbeCurrentAddr(v);
      sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
      VdbeComment((v, "set abort flag"));
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      sqlite3VdbeResolveLabel(v, addrOutputRow);
      addrOutputRow = sqlite3VdbeCurrentAddr(v);
      sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2); VdbeCoverage(v);

      VdbeComment((v, "Groupby result generator entry point"));
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      finalizeAggFunctions(pParse, &sAggInfo);
      sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, p->pEList, -1, &sSort,
                      &sDistinct, pDest,
                      addrOutputRow+1, addrSetAbort);
................................................................................
    explainTempTable(pParse, "DISTINCT");
  }

  /* If there is an ORDER BY clause, then we need to sort the results
  ** and send them to the callback one by one.
  */
  if( sSort.pOrderBy ){

    explainTempTable(pParse, sSort.nOBSat>0 ? "RIGHT PART OF ORDER BY":"ORDER BY");
    generateSortTail(pParse, p, &sSort, pEList->nExpr, pDest);
  }

  /* Jump here to skip this query
  */
  sqlite3VdbeResolveLabel(v, iEnd);

................................................................................
#if SELECTTRACE_ENABLED
  SELECTTRACE(1,pParse,p,("end processing\n"));
  pParse->nSelectIndent--;
#endif
  return rc;
}

#ifdef SQLITE_DEBUG
/*
** Generate a human-readable description of a the Select object.
*/
SQLITE_PRIVATE void sqlite3TreeViewSelect(TreeView *pView, const Select *p, u8 moreToFollow){
  int n = 0;
  pView = sqlite3TreeViewPush(pView, moreToFollow);
  sqlite3TreeViewLine(pView, "SELECT%s%s (0x%p) selFlags=0x%x",
    ((p->selFlags & SF_Distinct) ? " DISTINCT" : ""),
    ((p->selFlags & SF_Aggregate) ? " agg_flag" : ""), p, p->selFlags
  );
  if( p->pSrc && p->pSrc->nSrc ) n++;
  if( p->pWhere ) n++;
  if( p->pGroupBy ) n++;
  if( p->pHaving ) n++;
  if( p->pOrderBy ) n++;
  if( p->pLimit ) n++;
  if( p->pOffset ) n++;
  if( p->pPrior ) n++;
  sqlite3TreeViewExprList(pView, p->pEList, (n--)>0, "result-set");
  if( p->pSrc && p->pSrc->nSrc ){
    int i;
    pView = sqlite3TreeViewPush(pView, (n--)>0);
    sqlite3TreeViewLine(pView, "FROM");
    for(i=0; i<p->pSrc->nSrc; i++){
      struct SrcList_item *pItem = &p->pSrc->a[i];
      StrAccum x;
      char zLine[100];
      sqlite3StrAccumInit(&x, 0, zLine, sizeof(zLine), 0);
      sqlite3XPrintf(&x, 0, "{%d,*}", pItem->iCursor);
      if( pItem->zDatabase ){
        sqlite3XPrintf(&x, 0, " %s.%s", pItem->zDatabase, pItem->zName);
      }else if( pItem->zName ){
        sqlite3XPrintf(&x, 0, " %s", pItem->zName);
      }
      if( pItem->pTab ){
        sqlite3XPrintf(&x, 0, " tabname=%Q", pItem->pTab->zName);
      }
      if( pItem->zAlias ){
        sqlite3XPrintf(&x, 0, " (AS %s)", pItem->zAlias);
      }
      if( pItem->jointype & JT_LEFT ){
        sqlite3XPrintf(&x, 0, " LEFT-JOIN");
      }
      sqlite3StrAccumFinish(&x);
      sqlite3TreeViewItem(pView, zLine, i<p->pSrc->nSrc-1); 
      if( pItem->pSelect ){
        sqlite3TreeViewSelect(pView, pItem->pSelect, 0);
      }
      sqlite3TreeViewPop(pView);
    }
    sqlite3TreeViewPop(pView);
  }
  if( p->pWhere ){
    sqlite3TreeViewItem(pView, "WHERE", (n--)>0);
    sqlite3TreeViewExpr(pView, p->pWhere, 0);
    sqlite3TreeViewPop(pView);
  }
  if( p->pGroupBy ){
    sqlite3TreeViewExprList(pView, p->pGroupBy, (n--)>0, "GROUPBY");
  }
  if( p->pHaving ){
    sqlite3TreeViewItem(pView, "HAVING", (n--)>0);
    sqlite3TreeViewExpr(pView, p->pHaving, 0);
    sqlite3TreeViewPop(pView);
  }
  if( p->pOrderBy ){
    sqlite3TreeViewExprList(pView, p->pOrderBy, (n--)>0, "ORDERBY");
  }
  if( p->pLimit ){
    sqlite3TreeViewItem(pView, "LIMIT", (n--)>0);
    sqlite3TreeViewExpr(pView, p->pLimit, 0);
    sqlite3TreeViewPop(pView);
  }
  if( p->pOffset ){
    sqlite3TreeViewItem(pView, "OFFSET", (n--)>0);
    sqlite3TreeViewExpr(pView, p->pOffset, 0);
    sqlite3TreeViewPop(pView);
  }
  if( p->pPrior ){
    const char *zOp = "UNION";
    switch( p->op ){
      case TK_ALL:         zOp = "UNION ALL";  break;
      case TK_INTERSECT:   zOp = "INTERSECT";  break;
      case TK_EXCEPT:      zOp = "EXCEPT";     break;
    }
    sqlite3TreeViewItem(pView, zOp, (n--)>0);
    sqlite3TreeViewSelect(pView, p->pPrior, 0);
    sqlite3TreeViewPop(pView);
  }
  sqlite3TreeViewPop(pView);
}
#endif /* SQLITE_DEBUG */

/************** End of select.c **********************************************/
/************** Begin file table.c *******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

#endif /* SQLITE_OMIT_VIRTUALTABLE */

/************** End of vtab.c ************************************************/
/************** Begin file where.c *******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is responsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".

*/
/************** Include whereInt.h in the middle of where.c ******************/
/************** Begin file whereInt.h ****************************************/
/*
** 2013-11-12
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
................................................................................
** a separate source file for easier editing.
*/

/*
** Trace output macros
*/
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
/***/ int sqlite3WhereTrace = 0;
#endif
#if defined(SQLITE_DEBUG) \
    && (defined(SQLITE_TEST) || defined(SQLITE_ENABLE_WHERETRACE))
# define WHERETRACE(K,X)  if(sqlite3WhereTrace&(K)) sqlite3DebugPrintf X
# define WHERETRACE_ENABLED 1
#else
# define WHERETRACE(K,X)
................................................................................
*/
#define N_OR_COST 3
struct WhereOrSet {
  u16 n;                      /* Number of valid a[] entries */
  WhereOrCost a[N_OR_COST];   /* Set of best costs */
};


/* Forward declaration of methods */
static int whereLoopResize(sqlite3*, WhereLoop*, int);

/*
** Each instance of this object holds a sequence of WhereLoop objects
** that implement some or all of a query plan.
**
** Think of each WhereLoop object as a node in a graph with arcs
** showing dependencies and costs for travelling between nodes.  (That is
** not a completely accurate description because WhereLoop costs are a
................................................................................
** no gaps.
*/
struct WhereMaskSet {
  int n;                        /* Number of assigned cursor values */
  int ix[BMS];                  /* Cursor assigned to each bit */
};






/*
** This object is a convenience wrapper holding all information needed
** to construct WhereLoop objects for a particular query.
*/
struct WhereLoopBuilder {
  WhereInfo *pWInfo;        /* Information about this WHERE */
  WhereClause *pWC;         /* WHERE clause terms */
................................................................................
  int iBreak;               /* Jump here to break out of the loop */
  int savedNQueryLoop;      /* pParse->nQueryLoop outside the WHERE loop */
  int aiCurOnePass[2];      /* OP_OpenWrite cursors for the ONEPASS opt */
  WhereMaskSet sMaskSet;    /* Map cursor numbers to bitmasks */
  WhereClause sWC;          /* Decomposition of the WHERE clause */
  WhereLevel a[1];          /* Information about each nest loop in WHERE */
};

























































/*
** Bitmasks for the operators on WhereTerm objects.  These are all
** operators that are of interest to the query planner.  An
** OR-ed combination of these values can be used when searching for
** particular WhereTerms within a WhereClause.
*/
................................................................................
#define WHERE_MULTI_OR     0x00002000  /* OR using multiple indices */
#define WHERE_AUTO_INDEX   0x00004000  /* Uses an ephemeral index */
#define WHERE_SKIPSCAN     0x00008000  /* Uses the skip-scan algorithm */
#define WHERE_UNQ_WANTED   0x00010000  /* WHERE_ONEROW would have been helpful*/
#define WHERE_PARTIALIDX   0x00020000  /* The automatic index is partial */

/************** End of whereInt.h ********************************************/
/************** Continuing where we left off in where.c **********************/

/*
** Return the estimated number of output rows from a WHERE clause
*/
SQLITE_PRIVATE u64 sqlite3WhereOutputRowCount(WhereInfo *pWInfo){
  return sqlite3LogEstToInt(pWInfo->nRowOut);
}

/*
** Return one of the WHERE_DISTINCT_xxxxx values to indicate how this
** WHERE clause returns outputs for DISTINCT processing.
*/
SQLITE_PRIVATE int sqlite3WhereIsDistinct(WhereInfo *pWInfo){
  return pWInfo->eDistinct;
}

/*
** Return TRUE if the WHERE clause returns rows in ORDER BY order.
** Return FALSE if the output needs to be sorted.
*/
SQLITE_PRIVATE int sqlite3WhereIsOrdered(WhereInfo *pWInfo){
  return pWInfo->nOBSat;
}

/*
** Return the VDBE address or label to jump to in order to continue
** immediately with the next row of a WHERE clause.
*/
SQLITE_PRIVATE int sqlite3WhereContinueLabel(WhereInfo *pWInfo){
  assert( pWInfo->iContinue!=0 );
  return pWInfo->iContinue;
}

/*
** Return the VDBE address or label to jump to in order to break
** out of a WHERE loop.
*/
SQLITE_PRIVATE int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
  return pWInfo->iBreak;
}

/*
** Return TRUE if an UPDATE or DELETE statement can operate directly on
** the rowids returned by a WHERE clause.  Return FALSE if doing an
** UPDATE or DELETE might change subsequent WHERE clause results.
**
** If the ONEPASS optimization is used (if this routine returns true)
** then also write the indices of open cursors used by ONEPASS
** into aiCur[0] and aiCur[1].  iaCur[0] gets the cursor of the data
** table and iaCur[1] gets the cursor used by an auxiliary index.
** Either value may be -1, indicating that cursor is not used.
** Any cursors returned will have been opened for writing.
**
** aiCur[0] and aiCur[1] both get -1 if the where-clause logic is
** unable to use the ONEPASS optimization.
*/
SQLITE_PRIVATE int sqlite3WhereOkOnePass(WhereInfo *pWInfo, int *aiCur){
  memcpy(aiCur, pWInfo->aiCurOnePass, sizeof(int)*2);
  return pWInfo->okOnePass;
}

/*
** Move the content of pSrc into pDest
*/
static void whereOrMove(WhereOrSet *pDest, WhereOrSet *pSrc){
  pDest->n = pSrc->n;
  memcpy(pDest->a, pSrc->a, pDest->n*sizeof(pDest->a[0]));
}

/*
** Try to insert a new prerequisite/cost entry into the WhereOrSet pSet.
**
** The new entry might overwrite an existing entry, or it might be
** appended, or it might be discarded.  Do whatever is the right thing
** so that pSet keeps the N_OR_COST best entries seen so far.
*/
static int whereOrInsert(
  WhereOrSet *pSet,      /* The WhereOrSet to be updated */
  Bitmask prereq,        /* Prerequisites of the new entry */
  LogEst rRun,           /* Run-cost of the new entry */
  LogEst nOut            /* Number of outputs for the new entry */
){
  u16 i;
  WhereOrCost *p;
  for(i=pSet->n, p=pSet->a; i>0; i--, p++){
    if( rRun<=p->rRun && (prereq & p->prereq)==prereq ){
      goto whereOrInsert_done;
    }
    if( p->rRun<=rRun && (p->prereq & prereq)==p->prereq ){
      return 0;
    }
  }
  if( pSet->n<N_OR_COST ){
    p = &pSet->a[pSet->n++];
    p->nOut = nOut;
  }else{
    p = pSet->a;
    for(i=1; i<pSet->n; i++){
      if( p->rRun>pSet->a[i].rRun ) p = pSet->a + i;
    }
    if( p->rRun<=rRun ) return 0;
  }
whereOrInsert_done:
  p->prereq = prereq;
  p->rRun = rRun;
  if( p->nOut>nOut ) p->nOut = nOut;
  return 1;
}

/*
** Initialize a preallocated WhereClause structure.
*/
static void whereClauseInit(
  WhereClause *pWC,        /* The WhereClause to be initialized */
  WhereInfo *pWInfo        /* The WHERE processing context */
){
  pWC->pWInfo = pWInfo;
  pWC->pOuter = 0;
  pWC->nTerm = 0;
  pWC->nSlot = ArraySize(pWC->aStatic);
  pWC->a = pWC->aStatic;
}

/* Forward reference */
static void whereClauseClear(WhereClause*);

/*
** Deallocate all memory associated with a WhereOrInfo object.
*/
static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){
  whereClauseClear(&p->wc);



































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































  sqlite3DbFree(db, p);
}

/*
** Deallocate all memory associated with a WhereAndInfo object.
*/
static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){
  whereClauseClear(&p->wc);
  sqlite3DbFree(db, p);
}

/*
** Deallocate a WhereClause structure.  The WhereClause structure
** itself is not freed.  This routine is the inverse of whereClauseInit().
*/
static void whereClauseClear(WhereClause *pWC){
  int i;
  WhereTerm *a;
  sqlite3 *db = pWC->pWInfo->pParse->db;
  for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
    if( a->wtFlags & TERM_DYNAMIC ){
      sqlite3ExprDelete(db, a->pExpr);
    }
    if( a->wtFlags & TERM_ORINFO ){
      whereOrInfoDelete(db, a->u.pOrInfo);
    }else if( a->wtFlags & TERM_ANDINFO ){
      whereAndInfoDelete(db, a->u.pAndInfo);
    }
  }
  if( pWC->a!=pWC->aStatic ){
    sqlite3DbFree(db, pWC->a);
  }
}

/*
** Add a single new WhereTerm entry to the WhereClause object pWC.
** The new WhereTerm object is constructed from Expr p and with wtFlags.
** The index in pWC->a[] of the new WhereTerm is returned on success.
** 0 is returned if the new WhereTerm could not be added due to a memory
** allocation error.  The memory allocation failure will be recorded in
** the db->mallocFailed flag so that higher-level functions can detect it.
................................................................................
  pTerm->pExpr = sqlite3ExprSkipCollate(p);
  pTerm->wtFlags = wtFlags;
  pTerm->pWC = pWC;
  pTerm->iParent = -1;
  return idx;
}

/*
** This routine identifies subexpressions in the WHERE clause where
** each subexpression is separated by the AND operator or some other
** operator specified in the op parameter.  The WhereClause structure
** is filled with pointers to subexpressions.  For example:
**
**    WHERE  a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
**           \________/     \_______________/     \________________/
**            slot[0]            slot[1]               slot[2]
**
** The original WHERE clause in pExpr is unaltered.  All this routine
** does is make slot[] entries point to substructure within pExpr.
**
** In the previous sentence and in the diagram, "slot[]" refers to
** the WhereClause.a[] array.  The slot[] array grows as needed to contain
** all terms of the WHERE clause.
*/
static void whereSplit(WhereClause *pWC, Expr *pExpr, u8 op){
  Expr *pE2 = sqlite3ExprSkipCollate(pExpr);
  pWC->op = op;
  if( pE2==0 ) return;
  if( pE2->op!=op ){
    whereClauseInsert(pWC, pExpr, 0);
  }else{
    whereSplit(pWC, pE2->pLeft, op);
    whereSplit(pWC, pE2->pRight, op);
  }
}

/*
** Initialize a WhereMaskSet object
*/
#define initMaskSet(P)  (P)->n=0

/*
** Return the bitmask for the given cursor number.  Return 0 if
** iCursor is not in the set.
*/
static Bitmask getMask(WhereMaskSet *pMaskSet, int iCursor){
  int i;
  assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 );
  for(i=0; i<pMaskSet->n; i++){
    if( pMaskSet->ix[i]==iCursor ){
      return MASKBIT(i);
    }
  }
  return 0;
}

/*
** Create a new mask for cursor iCursor.
**
** There is one cursor per table in the FROM clause.  The number of
** tables in the FROM clause is limited by a test early in the
** sqlite3WhereBegin() routine.  So we know that the pMaskSet->ix[]
** array will never overflow.
*/
static void createMask(WhereMaskSet *pMaskSet, int iCursor){
  assert( pMaskSet->n < ArraySize(pMaskSet->ix) );
  pMaskSet->ix[pMaskSet->n++] = iCursor;
}

/*
** These routines walk (recursively) an expression tree and generate
** a bitmask indicating which tables are used in that expression
** tree.
*/
static Bitmask exprListTableUsage(WhereMaskSet*, ExprList*);
static Bitmask exprSelectTableUsage(WhereMaskSet*, Select*);
static Bitmask exprTableUsage(WhereMaskSet *pMaskSet, Expr *p){
  Bitmask mask = 0;
  if( p==0 ) return 0;
  if( p->op==TK_COLUMN ){
    mask = getMask(pMaskSet, p->iTable);
    return mask;
  }
  mask = exprTableUsage(pMaskSet, p->pRight);
  mask |= exprTableUsage(pMaskSet, p->pLeft);
  if( ExprHasProperty(p, EP_xIsSelect) ){
    mask |= exprSelectTableUsage(pMaskSet, p->x.pSelect);
  }else{
    mask |= exprListTableUsage(pMaskSet, p->x.pList);
  }
  return mask;
}
static Bitmask exprListTableUsage(WhereMaskSet *pMaskSet, ExprList *pList){
  int i;
  Bitmask mask = 0;
  if( pList ){
    for(i=0; i<pList->nExpr; i++){
      mask |= exprTableUsage(pMaskSet, pList->a[i].pExpr);
    }
  }
  return mask;
}
static Bitmask exprSelectTableUsage(WhereMaskSet *pMaskSet, Select *pS){
  Bitmask mask = 0;
  while( pS ){
    SrcList *pSrc = pS->pSrc;
    mask |= exprListTableUsage(pMaskSet, pS->pEList);
    mask |= exprListTableUsage(pMaskSet, pS->pGroupBy);
    mask |= exprListTableUsage(pMaskSet, pS->pOrderBy);
    mask |= exprTableUsage(pMaskSet, pS->pWhere);
    mask |= exprTableUsage(pMaskSet, pS->pHaving);
    if( ALWAYS(pSrc!=0) ){
      int i;
      for(i=0; i<pSrc->nSrc; i++){
        mask |= exprSelectTableUsage(pMaskSet, pSrc->a[i].pSelect);
        mask |= exprTableUsage(pMaskSet, pSrc->a[i].pOn);
      }
    }
    pS = pS->pPrior;
  }
  return mask;
}

/*
** Return TRUE if the given operator is one of the operators that is
** allowed for an indexable WHERE clause term.  The allowed operators are
** "=", "<", ">", "<=", ">=", "IN", and "IS NULL"
*/
static int allowedOp(int op){
  assert( TK_GT>TK_EQ && TK_GT<TK_GE );
................................................................................
  assert( op!=TK_LE || c==WO_LE );
  assert( op!=TK_GT || c==WO_GT );
  assert( op!=TK_GE || c==WO_GE );
  assert( op!=TK_IS || c==WO_IS );
  return c;
}

/*
** Advance to the next WhereTerm that matches according to the criteria
** established when the pScan object was initialized by whereScanInit().
** Return NULL if there are no more matching WhereTerms.
*/
static WhereTerm *whereScanNext(WhereScan *pScan){
  int iCur;            /* The cursor on the LHS of the term */
  int iColumn;         /* The column on the LHS of the term.  -1 for IPK */
  Expr *pX;            /* An expression being tested */
  WhereClause *pWC;    /* Shorthand for pScan->pWC */
  WhereTerm *pTerm;    /* The term being tested */
  int k = pScan->k;    /* Where to start scanning */

  while( pScan->iEquiv<=pScan->nEquiv ){
    iCur = pScan->aEquiv[pScan->iEquiv-2];
    iColumn = pScan->aEquiv[pScan->iEquiv-1];
    while( (pWC = pScan->pWC)!=0 ){
      for(pTerm=pWC->a+k; k<pWC->nTerm; k++, pTerm++){
        if( pTerm->leftCursor==iCur
         && pTerm->u.leftColumn==iColumn
         && (pScan->iEquiv<=2 || !ExprHasProperty(pTerm->pExpr, EP_FromJoin))
        ){
          if( (pTerm->eOperator & WO_EQUIV)!=0
           && pScan->nEquiv<ArraySize(pScan->aEquiv)
          ){
            int j;
            pX = sqlite3ExprSkipCollate(pTerm->pExpr->pRight);
            assert( pX->op==TK_COLUMN );
            for(j=0; j<pScan->nEquiv; j+=2){
              if( pScan->aEquiv[j]==pX->iTable
               && pScan->aEquiv[j+1]==pX->iColumn ){
                  break;
              }
            }
            if( j==pScan->nEquiv ){
              pScan->aEquiv[j] = pX->iTable;
              pScan->aEquiv[j+1] = pX->iColumn;
              pScan->nEquiv += 2;
            }
          }
          if( (pTerm->eOperator & pScan->opMask)!=0 ){
            /* Verify the affinity and collating sequence match */
            if( pScan->zCollName && (pTerm->eOperator & WO_ISNULL)==0 ){
              CollSeq *pColl;
              Parse *pParse = pWC->pWInfo->pParse;
              pX = pTerm->pExpr;
              if( !sqlite3IndexAffinityOk(pX, pScan->idxaff) ){
                continue;
              }
              assert(pX->pLeft);
              pColl = sqlite3BinaryCompareCollSeq(pParse,
                                                  pX->pLeft, pX->pRight);
              if( pColl==0 ) pColl = pParse->db->pDfltColl;
              if( sqlite3StrICmp(pColl->zName, pScan->zCollName) ){
                continue;
              }
            }
            if( (pTerm->eOperator & (WO_EQ|WO_IS))!=0
             && (pX = pTerm->pExpr->pRight)->op==TK_COLUMN
             && pX->iTable==pScan->aEquiv[0]
             && pX->iColumn==pScan->aEquiv[1]
            ){
              testcase( pTerm->eOperator & WO_IS );
              continue;
            }
            pScan->k = k+1;
            return pTerm;
          }
        }
      }
      pScan->pWC = pScan->pWC->pOuter;
      k = 0;
    }
    pScan->pWC = pScan->pOrigWC;
    k = 0;
    pScan->iEquiv += 2;
  }
  return 0;
}

/*
** Initialize a WHERE clause scanner object.  Return a pointer to the
** first match.  Return NULL if there are no matches.
**
** The scanner will be searching the WHERE clause pWC.  It will look
** for terms of the form "X <op> <expr>" where X is column iColumn of table
** iCur.  The <op> must be one of the operators described by opMask.
**
** If the search is for X and the WHERE clause contains terms of the
** form X=Y then this routine might also return terms of the form
** "Y <op> <expr>".  The number of levels of transitivity is limited,
** but is enough to handle most commonly occurring SQL statements.
**
** If X is not the INTEGER PRIMARY KEY then X must be compatible with
** index pIdx.
*/
static WhereTerm *whereScanInit(
  WhereScan *pScan,       /* The WhereScan object being initialized */
  WhereClause *pWC,       /* The WHERE clause to be scanned */
  int iCur,               /* Cursor to scan for */
  int iColumn,            /* Column to scan for */
  u32 opMask,             /* Operator(s) to scan for */
  Index *pIdx             /* Must be compatible with this index */
){
  int j;

  /* memset(pScan, 0, sizeof(*pScan)); */
  pScan->pOrigWC = pWC;
  pScan->pWC = pWC;
  if( pIdx && iColumn>=0 ){
    pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity;
    for(j=0; pIdx->aiColumn[j]!=iColumn; j++){
      if( NEVER(j>pIdx->nColumn) ) return 0;
    }
    pScan->zCollName = pIdx->azColl[j];
  }else{
    pScan->idxaff = 0;
    pScan->zCollName = 0;
  }
  pScan->opMask = opMask;
  pScan->k = 0;
  pScan->aEquiv[0] = iCur;
  pScan->aEquiv[1] = iColumn;
  pScan->nEquiv = 2;
  pScan->iEquiv = 2;
  return whereScanNext(pScan);
}

/*
** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
** where X is a reference to the iColumn of table iCur and <op> is one of
** the WO_xx operator codes specified by the op parameter.
** Return a pointer to the term.  Return 0 if not found.
**
** The term returned might by Y=<expr> if there is another constraint in
** the WHERE clause that specifies that X=Y.  Any such constraints will be
** identified by the WO_EQUIV bit in the pTerm->eOperator field.  The
** aEquiv[] array holds X and all its equivalents, with each SQL variable
** taking up two slots in aEquiv[].  The first slot is for the cursor number
** and the second is for the column number.  There are 22 slots in aEquiv[]
** so that means we can look for X plus up to 10 other equivalent values.
** Hence a search for X will return <expr> if X=A1 and A1=A2 and A2=A3
** and ... and A9=A10 and A10=<expr>.
**
** If there are multiple terms in the WHERE clause of the form "X <op> <expr>"
** then try for the one with no dependencies on <expr> - in other words where
** <expr> is a constant expression of some kind.  Only return entries of
** the form "X <op> Y" where Y is a column in another table if no terms of
** the form "X <op> <const-expr>" exist.   If no terms with a constant RHS
** exist, try to return a term that does not use WO_EQUIV.
*/
static WhereTerm *findTerm(
  WhereClause *pWC,     /* The WHERE clause to be searched */
  int iCur,             /* Cursor number of LHS */
  int iColumn,          /* Column number of LHS */
  Bitmask notReady,     /* RHS must not overlap with this mask */
  u32 op,               /* Mask of WO_xx values describing operator */
  Index *pIdx           /* Must be compatible with this index, if not NULL */
){
  WhereTerm *pResult = 0;
  WhereTerm *p;
  WhereScan scan;

  p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx);
  op &= WO_EQ|WO_IS;
  while( p ){
    if( (p->prereqRight & notReady)==0 ){
      if( p->prereqRight==0 && (p->eOperator&op)!=0 ){
        testcase( p->eOperator & WO_IS );
        return p;
      }
      if( pResult==0 ) pResult = p;
    }
    p = whereScanNext(&scan);
  }
  return pResult;
}

/* Forward reference */
static void exprAnalyze(SrcList*, WhereClause*, int);

/*
** Call exprAnalyze on all terms in a WHERE clause.  
*/
static void exprAnalyzeAll(
  SrcList *pTabList,       /* the FROM clause */
  WhereClause *pWC         /* the WHERE clause to be analyzed */
){
  int i;
  for(i=pWC->nTerm-1; i>=0; i--){
    exprAnalyze(pTabList, pWC, i);
  }
}

#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
/*
** Check to see if the given expression is a LIKE or GLOB operator that
** can be optimized using inequality constraints.  Return TRUE if it is
** so and false if not.
**
................................................................................
  assert( pLeft->iColumn!=(-1) ); /* Because IPK never has AFF_TEXT */

  pRight = sqlite3ExprSkipCollate(pList->a[0].pExpr);
  op = pRight->op;
  if( op==TK_VARIABLE ){
    Vdbe *pReprepare = pParse->pReprepare;
    int iCol = pRight->iColumn;
    pVal = sqlite3VdbeGetBoundValue(pReprepare, iCol, SQLITE_AFF_NONE);
    if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){
      z = (char *)sqlite3_value_text(pVal);
    }
    sqlite3VdbeSetVarmask(pParse->pVdbe, iCol);
    assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER );
  }else if( op==TK_STRING ){
    z = pRight->u.zToken;
................................................................................
**
** then create a new virtual term like this:
**
**      x IN (expr1,expr2,expr3)
**
** CASE 2:
**
** If there are exactly two disjuncts one side has x>A and the other side
** has x=A (for the same x and A) then add a new virtual conjunct term to the
** WHERE clause of the form "x>=A".  Example:
**
**      x>A OR (x=A AND y>B)    adds:    x>=A
**
** The added conjunct can sometimes be helpful in query planning.
**
................................................................................
**
** From another point of view, "indexable" means that the subterm could
** potentially be used with an index if an appropriate index exists.
** This analysis does not consider whether or not the index exists; that
** is decided elsewhere.  This analysis only looks at whether subterms
** appropriate for indexing exist.
**
** All examples A through E above satisfy case 2.  But if a term
** also satisfies case 1 (such as B) we know that the optimizer will
** always prefer case 1, so in that case we pretend that case 2 is not
** satisfied.
**
** It might be the case that multiple tables are indexable.  For example,
** (E) above is indexable on tables P, Q, and R.
**
** Terms that satisfy case 2 are candidates for lookup by using
** separate indices to find rowids for each subterm and composing
** the union of all rowids using a RowSet object.  This is similar
** to "bitmap indices" in other database engines.
**
** OTHERWISE:
**
** If neither case 1 nor case 2 apply, then leave the eOperator set to
** zero.  This term is not useful for search.
*/
static void exprAnalyzeOrTerm(
  SrcList *pSrc,            /* the FROM clause */
  WhereClause *pWC,         /* the complete WHERE clause */
  int idxTerm               /* Index of the OR-term to be analyzed */
){
................................................................................
  */
  assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
  assert( pExpr->op==TK_OR );
  pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
  if( pOrInfo==0 ) return;
  pTerm->wtFlags |= TERM_ORINFO;
  pOrWc = &pOrInfo->wc;
  whereClauseInit(pOrWc, pWInfo);
  whereSplit(pOrWc, pExpr, TK_OR);
  exprAnalyzeAll(pSrc, pOrWc);
  if( db->mallocFailed ) return;
  assert( pOrWc->nTerm>=2 );

  /*
  ** Compute the set of tables that might satisfy cases 1 or 2.
  */
  indexable = ~(Bitmask)0;
  chngToIN = ~(Bitmask)0;
  for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){
    if( (pOrTerm->eOperator & WO_SINGLE)==0 ){
      WhereAndInfo *pAndInfo;
      assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 );
................................................................................
        WhereTerm *pAndTerm;
        int j;
        Bitmask b = 0;
        pOrTerm->u.pAndInfo = pAndInfo;
        pOrTerm->wtFlags |= TERM_ANDINFO;
        pOrTerm->eOperator = WO_AND;
        pAndWC = &pAndInfo->wc;
        whereClauseInit(pAndWC, pWC->pWInfo);
        whereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
        exprAnalyzeAll(pSrc, pAndWC);
        pAndWC->pOuter = pWC;
        testcase( db->mallocFailed );
        if( !db->mallocFailed ){
          for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
            assert( pAndTerm->pExpr );
            if( allowedOp(pAndTerm->pExpr->op) ){
              b |= getMask(&pWInfo->sMaskSet, pAndTerm->leftCursor);
            }
          }
        }
        indexable &= b;
      }
    }else if( pOrTerm->wtFlags & TERM_COPIED ){
      /* Skip this term for now.  We revisit it when we process the
      ** corresponding TERM_VIRTUAL term */
    }else{
      Bitmask b;
      b = getMask(&pWInfo->sMaskSet, pOrTerm->leftCursor);
      if( pOrTerm->wtFlags & TERM_VIRTUAL ){
        WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent];
        b |= getMask(&pWInfo->sMaskSet, pOther->leftCursor);
      }
      indexable &= b;
      if( (pOrTerm->eOperator & WO_EQ)==0 ){
        chngToIN = 0;
      }else{
        chngToIN &= b;
      }
................................................................................
        pOrTerm->wtFlags &= ~TERM_OR_OK;
        if( pOrTerm->leftCursor==iCursor ){
          /* This is the 2-bit case and we are on the second iteration and
          ** current term is from the first iteration.  So skip this term. */
          assert( j==1 );
          continue;
        }

        if( (chngToIN & getMask(&pWInfo->sMaskSet, pOrTerm->leftCursor))==0 ){
          /* This term must be of the form t1.a==t2.b where t2 is in the
          ** chngToIN set but t1 is not.  This term will be either preceded
          ** or follwed by an inverted copy (t2.b==t1.a).  Skip this term 
          ** and use its inversion. */
          testcase( pOrTerm->wtFlags & TERM_COPIED );
          testcase( pOrTerm->wtFlags & TERM_VIRTUAL );
          assert( pOrTerm->wtFlags & (TERM_COPIED|TERM_VIRTUAL) );
................................................................................
        break;
      }
      if( i<0 ){
        /* No candidate table+column was found.  This can only occur
        ** on the second iteration */
        assert( j==1 );
        assert( IsPowerOfTwo(chngToIN) );
        assert( chngToIN==getMask(&pWInfo->sMaskSet, iCursor) );
        break;
      }
      testcase( j==1 );

      /* We have found a candidate table and column.  Check to see if that
      ** table and column is common to every term in the OR clause */
      okToChngToIN = 1;
................................................................................

/*
** We already know that pExpr is a binary operator where both operands are
** column references.  This routine checks to see if pExpr is an equivalence
** relation:
**   1.  The SQLITE_Transitive optimization must be enabled
**   2.  Must be either an == or an IS operator
**   3.  Not originating the ON clause of an OUTER JOIN
**   4.  The affinities of A and B must be compatible
**   5a. Both operands use the same collating sequence OR
**   5b. The overall collating sequence is BINARY
** If this routine returns TRUE, that means that the RHS can be substituted
** for the LHS anyplace else in the WHERE clause where the LHS column occurs.
** This is an optimization.  No harm comes from returning 0.  But if 1 is
** returned when it should not be, then incorrect answers might result.
................................................................................
  /* Since pLeft and pRight are both a column references, their collating
  ** sequence should always be defined. */
  zColl1 = ALWAYS(pColl) ? pColl->zName : 0;
  pColl = sqlite3ExprCollSeq(pParse, pExpr->pRight);
  zColl2 = ALWAYS(pColl) ? pColl->zName : 0;
  return sqlite3StrICmp(zColl1, zColl2)==0;
}



























/*
** The input to this routine is an WhereTerm structure with only the
** "pExpr" field filled in.  The job of this routine is to analyze the
** subexpression and populate all the other fields of the WhereTerm
** structure.
**
................................................................................
  if( db->mallocFailed ){
    return;
  }
  pTerm = &pWC->a[idxTerm];
  pMaskSet = &pWInfo->sMaskSet;
  pExpr = pTerm->pExpr;
  assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE );
  prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft);
  op = pExpr->op;
  if( op==TK_IN ){
    assert( pExpr->pRight==0 );
    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
      pTerm->prereqRight = exprSelectTableUsage(pMaskSet, pExpr->x.pSelect);
    }else{
      pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->x.pList);
    }
  }else if( op==TK_ISNULL ){
    pTerm->prereqRight = 0;
  }else{
    pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight);
  }
  prereqAll = exprTableUsage(pMaskSet, pExpr);
  if( ExprHasProperty(pExpr, EP_FromJoin) ){
    Bitmask x = getMask(pMaskSet, pExpr->iRightJoinTable);
    prereqAll |= x;
    extraRight = x-1;  /* ON clause terms may not be used with an index
                       ** on left table of a LEFT JOIN.  Ticket #3015 */
  }
  pTerm->prereqAll = prereqAll;
  pTerm->leftCursor = -1;
  pTerm->iParent = -1;
................................................................................
    int idxNew;
    Expr *pRight, *pLeft;
    WhereTerm *pNewTerm;
    Bitmask prereqColumn, prereqExpr;

    pRight = pExpr->x.pList->a[0].pExpr;
    pLeft = pExpr->x.pList->a[1].pExpr;
    prereqExpr = exprTableUsage(pMaskSet, pRight);
    prereqColumn = exprTableUsage(pMaskSet, pLeft);
    if( (prereqExpr & prereqColumn)==0 ){
      Expr *pNewExpr;
      pNewExpr = sqlite3PExpr(pParse, TK_MATCH, 
                              0, sqlite3ExprDup(db, pRight, 0), 0);
      idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
      testcase( idxNew==0 );
      pNewTerm = &pWC->a[idxNew];
................................................................................
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */

  /* Prevent ON clause terms of a LEFT JOIN from being used to drive
  ** an index for tables to the left of the join.
  */
  pTerm->prereqRight |= extraRight;
}




















































































































































































































































































































































































































































































/*
** This function searches pList for an entry that matches the iCol-th column
** of index pIdx.
**
** If such an expression is found, its index in pList->a[] is returned. If
** no expression is found, -1 is returned.
................................................................................
  return -1;
}

/*
** Return true if the DISTINCT expression-list passed as the third argument
** is redundant.
**
** A DISTINCT list is redundant if the database contains some subset of
** columns that are unique and non-null.
*/
static int isDistinctRedundant(
  Parse *pParse,            /* Parsing context */
  SrcList *pTabList,        /* The FROM clause */
  WhereClause *pWC,         /* The WHERE clause */
  ExprList *pDistinct       /* The result set that needs to be DISTINCT */
){
................................................................................
  **   3. All of those index columns for which the WHERE clause does not
  **      contain a "col=X" term are subject to a NOT NULL constraint.
  */
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    if( !IsUniqueIndex(pIdx) ) continue;
    for(i=0; i<pIdx->nKeyCol; i++){
      i16 iCol = pIdx->aiColumn[i];
      if( 0==findTerm(pWC, iBase, iCol, ~(Bitmask)0, WO_EQ, pIdx) ){
        int iIdxCol = findIndexCol(pParse, pDistinct, iBase, pIdx, i);
        if( iIdxCol<0 || pTab->aCol[iCol].notNull==0 ){
          break;
        }
      }
    }
    if( i==pIdx->nKeyCol ){
................................................................................
** Allocate and populate an sqlite3_index_info structure. It is the 
** responsibility of the caller to eventually release the structure
** by passing the pointer returned by this function to sqlite3_free().
*/
static sqlite3_index_info *allocateIndexInfo(
  Parse *pParse,
  WhereClause *pWC,

  struct SrcList_item *pSrc,
  ExprList *pOrderBy
){
  int i, j;
  int nTerm;
  struct sqlite3_index_constraint *pIdxCons;
  struct sqlite3_index_orderby *pIdxOrderBy;
................................................................................
  int nOrderBy;
  sqlite3_index_info *pIdxInfo;

  /* Count the number of possible WHERE clause constraints referring
  ** to this virtual table */
  for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
    if( pTerm->leftCursor != pSrc->iCursor ) continue;

    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
    testcase( pTerm->eOperator & WO_IN );
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_IS );
    testcase( pTerm->eOperator & WO_ALL );
    if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
    if( pTerm->wtFlags & TERM_VNULL ) continue;
................................................................................
  *(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy;
  *(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage =
                                                                   pUsage;

  for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
    u8 op;
    if( pTerm->leftCursor != pSrc->iCursor ) continue;

    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
    testcase( pTerm->eOperator & WO_IN );
    testcase( pTerm->eOperator & WO_IS );
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_ALL );
    if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
    if( pTerm->wtFlags & TERM_VNULL ) continue;
................................................................................
    WHERETRACE(0x10,("IN row estimate: est=%d\n", nRowEst));
  }
  assert( pBuilder->nRecValid==nRecValid );
  return rc;
}
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */

/*
** Disable a term in the WHERE clause.  Except, do not disable the term
** if it controls a LEFT OUTER JOIN and it did not originate in the ON
** or USING clause of that join.
**
** Consider the term t2.z='ok' in the following queries:
**
**   (1)  SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok'
**   (2)  SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok'
**   (3)  SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok'
**
** The t2.z='ok' is disabled in the in (2) because it originates
** in the ON clause.  The term is disabled in (3) because it is not part
** of a LEFT OUTER JOIN.  In (1), the term is not disabled.
**
** Disabling a term causes that term to not be tested in the inner loop
** of the join.  Disabling is an optimization.  When terms are satisfied
** by indices, we disable them to prevent redundant tests in the inner
** loop.  We would get the correct results if nothing were ever disabled,
** but joins might run a little slower.  The trick is to disable as much
** as we can without disabling too much.  If we disabled in (1), we'd get
** the wrong answer.  See ticket #813.
**
** If all the children of a term are disabled, then that term is also
** automatically disabled.  In this way, terms get disabled if derived
** virtual terms are tested first.  For example:
**
**      x GLOB 'abc*' AND x>='abc' AND x<'acd'
**      \___________/     \______/     \_____/
**         parent          child1       child2
**
** Only the parent term was in the original WHERE clause.  The child1
** and child2 terms were added by the LIKE optimization.  If both of
** the virtual child terms are valid, then testing of the parent can be 
** skipped.
**
** Usually the parent term is marked as TERM_CODED.  But if the parent
** term was originally TERM_LIKE, then the parent gets TERM_LIKECOND instead.
** The TERM_LIKECOND marking indicates that the term should be coded inside
** a conditional such that is only evaluated on the second pass of a
** LIKE-optimization loop, when scanning BLOBs instead of strings.
*/
static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
  int nLoop = 0;
  while( pTerm
      && (pTerm->wtFlags & TERM_CODED)==0
      && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
      && (pLevel->notReady & pTerm->prereqAll)==0
  ){
    if( nLoop && (pTerm->wtFlags & TERM_LIKE)!=0 ){
      pTerm->wtFlags |= TERM_LIKECOND;
    }else{
      pTerm->wtFlags |= TERM_CODED;
    }
    if( pTerm->iParent<0 ) break;
    pTerm = &pTerm->pWC->a[pTerm->iParent];
    pTerm->nChild--;
    if( pTerm->nChild!=0 ) break;
    nLoop++;
  }
}

/*
** Code an OP_Affinity opcode to apply the column affinity string zAff
** to the n registers starting at base. 
**
** As an optimization, SQLITE_AFF_NONE entries (which are no-ops) at the
** beginning and end of zAff are ignored.  If all entries in zAff are
** SQLITE_AFF_NONE, then no code gets generated.
**
** This routine makes its own copy of zAff so that the caller is free
** to modify zAff after this routine returns.
*/
static void codeApplyAffinity(Parse *pParse, int base, int n, char *zAff){
  Vdbe *v = pParse->pVdbe;
  if( zAff==0 ){
    assert( pParse->db->mallocFailed );
    return;
  }
  assert( v!=0 );

  /* Adjust base and n to skip over SQLITE_AFF_NONE entries at the beginning
  ** and end of the affinity string.
  */
  while( n>0 && zAff[0]==SQLITE_AFF_NONE ){
    n--;
    base++;
    zAff++;
  }
  while( n>1 && zAff[n-1]==SQLITE_AFF_NONE ){
    n--;
  }

  /* Code the OP_Affinity opcode if there is anything left to do. */
  if( n>0 ){
    sqlite3VdbeAddOp2(v, OP_Affinity, base, n);
    sqlite3VdbeChangeP4(v, -1, zAff, n);
    sqlite3ExprCacheAffinityChange(pParse, base, n);
  }
}


/*
** Generate code for a single equality term of the WHERE clause.  An equality
** term can be either X=expr or X IN (...).   pTerm is the term to be 
** coded.
**
** The current value for the constraint is left in register iReg.
**
** For a constraint of the form X=expr, the expression is evaluated and its
** result is left on the stack.  For constraints of the form X IN (...)
** this routine sets up a loop that will iterate over all values of X.
*/
static int codeEqualityTerm(
  Parse *pParse,      /* The parsing context */
  WhereTerm *pTerm,   /* The term of the WHERE clause to be coded */
  WhereLevel *pLevel, /* The level of the FROM clause we are working on */
  int iEq,            /* Index of the equality term within this level */
  int bRev,           /* True for reverse-order IN operations */
  int iTarget         /* Attempt to leave results in this register */
){
  Expr *pX = pTerm->pExpr;
  Vdbe *v = pParse->pVdbe;
  int iReg;                  /* Register holding results */

  assert( iTarget>0 );
  if( pX->op==TK_EQ || pX->op==TK_IS ){
    iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);
  }else if( pX->op==TK_ISNULL ){
    iReg = iTarget;
    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
#ifndef SQLITE_OMIT_SUBQUERY
  }else{
    int eType;
    int iTab;
    struct InLoop *pIn;
    WhereLoop *pLoop = pLevel->pWLoop;

    if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0
      && pLoop->u.btree.pIndex!=0
      && pLoop->u.btree.pIndex->aSortOrder[iEq]
    ){
      testcase( iEq==0 );
      testcase( bRev );
      bRev = !bRev;
    }
    assert( pX->op==TK_IN );
    iReg = iTarget;
    eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0);
    if( eType==IN_INDEX_INDEX_DESC ){
      testcase( bRev );
      bRev = !bRev;
    }
    iTab = pX->iTable;
    sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iTab, 0);
    VdbeCoverageIf(v, bRev);
    VdbeCoverageIf(v, !bRev);
    assert( (pLoop->wsFlags & WHERE_MULTI_OR)==0 );
    pLoop->wsFlags |= WHERE_IN_ABLE;
    if( pLevel->u.in.nIn==0 ){
      pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
    }
    pLevel->u.in.nIn++;
    pLevel->u.in.aInLoop =
       sqlite3DbReallocOrFree(pParse->db, pLevel->u.in.aInLoop,
                              sizeof(pLevel->u.in.aInLoop[0])*pLevel->u.in.nIn);
    pIn = pLevel->u.in.aInLoop;
    if( pIn ){
      pIn += pLevel->u.in.nIn - 1;
      pIn->iCur = iTab;
      if( eType==IN_INDEX_ROWID ){
        pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iReg);
      }else{
        pIn->addrInTop = sqlite3VdbeAddOp3(v, OP_Column, iTab, 0, iReg);
      }
      pIn->eEndLoopOp = bRev ? OP_PrevIfOpen : OP_NextIfOpen;
      sqlite3VdbeAddOp1(v, OP_IsNull, iReg); VdbeCoverage(v);
    }else{
      pLevel->u.in.nIn = 0;
    }
#endif
  }
  disableTerm(pLevel, pTerm);
  return iReg;
}

/*
** Generate code that will evaluate all == and IN constraints for an
** index scan.
**
** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c).
** Suppose the WHERE clause is this:  a==5 AND b IN (1,2,3) AND c>5 AND c<10
** The index has as many as three equality constraints, but in this
** example, the third "c" value is an inequality.  So only two 
** constraints are coded.  This routine will generate code to evaluate
** a==5 and b IN (1,2,3).  The current values for a and b will be stored
** in consecutive registers and the index of the first register is returned.
**
** In the example above nEq==2.  But this subroutine works for any value
** of nEq including 0.  If nEq==0, this routine is nearly a no-op.
** The only thing it does is allocate the pLevel->iMem memory cell and
** compute the affinity string.
**
** The nExtraReg parameter is 0 or 1.  It is 0 if all WHERE clause constraints
** are == or IN and are covered by the nEq.  nExtraReg is 1 if there is
** an inequality constraint (such as the "c>=5 AND c<10" in the example) that
** occurs after the nEq quality constraints.
**
** This routine allocates a range of nEq+nExtraReg memory cells and returns
** the index of the first memory cell in that range. The code that
** calls this routine will use that memory range to store keys for
** start and termination conditions of the loop.
** key value of the loop.  If one or more IN operators appear, then
** this routine allocates an additional nEq memory cells for internal
** use.
**
** Before returning, *pzAff is set to point to a buffer containing a
** copy of the column affinity string of the index allocated using
** sqlite3DbMalloc(). Except, entries in the copy of the string associated
** with equality constraints that use NONE affinity are set to
** SQLITE_AFF_NONE. This is to deal with SQL such as the following:
**
**   CREATE TABLE t1(a TEXT PRIMARY KEY, b);
**   SELECT ... FROM t1 AS t2, t1 WHERE t1.a = t2.b;
**
** In the example above, the index on t1(a) has TEXT affinity. But since
** the right hand side of the equality constraint (t2.b) has NONE affinity,
** no conversion should be attempted before using a t2.b value as part of
** a key to search the index. Hence the first byte in the returned affinity
** string in this example would be set to SQLITE_AFF_NONE.
*/
static int codeAllEqualityTerms(
  Parse *pParse,        /* Parsing context */
  WhereLevel *pLevel,   /* Which nested loop of the FROM we are coding */
  int bRev,             /* Reverse the order of IN operators */
  int nExtraReg,        /* Number of extra registers to allocate */
  char **pzAff          /* OUT: Set to point to affinity string */
){
  u16 nEq;                      /* The number of == or IN constraints to code */
  u16 nSkip;                    /* Number of left-most columns to skip */
  Vdbe *v = pParse->pVdbe;      /* The vm under construction */
  Index *pIdx;                  /* The index being used for this loop */
  WhereTerm *pTerm;             /* A single constraint term */
  WhereLoop *pLoop;             /* The WhereLoop object */
  int j;                        /* Loop counter */
  int regBase;                  /* Base register */
  int nReg;                     /* Number of registers to allocate */
  char *zAff;                   /* Affinity string to return */

  /* This module is only called on query plans that use an index. */
  pLoop = pLevel->pWLoop;
  assert( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 );
  nEq = pLoop->u.btree.nEq;
  nSkip = pLoop->nSkip;
  pIdx = pLoop->u.btree.pIndex;
  assert( pIdx!=0 );

  /* Figure out how many memory cells we will need then allocate them.
  */
  regBase = pParse->nMem + 1;
  nReg = pLoop->u.btree.nEq + nExtraReg;
  pParse->nMem += nReg;

  zAff = sqlite3DbStrDup(pParse->db, sqlite3IndexAffinityStr(v, pIdx));
  if( !zAff ){
    pParse->db->mallocFailed = 1;
  }

  if( nSkip ){
    int iIdxCur = pLevel->iIdxCur;
    sqlite3VdbeAddOp1(v, (bRev?OP_Last:OP_Rewind), iIdxCur);
    VdbeCoverageIf(v, bRev==0);
    VdbeCoverageIf(v, bRev!=0);
    VdbeComment((v, "begin skip-scan on %s", pIdx->zName));
    j = sqlite3VdbeAddOp0(v, OP_Goto);
    pLevel->addrSkip = sqlite3VdbeAddOp4Int(v, (bRev?OP_SeekLT:OP_SeekGT),
                            iIdxCur, 0, regBase, nSkip);
    VdbeCoverageIf(v, bRev==0);
    VdbeCoverageIf(v, bRev!=0);
    sqlite3VdbeJumpHere(v, j);
    for(j=0; j<nSkip; j++){
      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, j, regBase+j);
      assert( pIdx->aiColumn[j]>=0 );
      VdbeComment((v, "%s", pIdx->pTable->aCol[pIdx->aiColumn[j]].zName));
    }
  }    

  /* Evaluate the equality constraints
  */
  assert( zAff==0 || (int)strlen(zAff)>=nEq );
  for(j=nSkip; j<nEq; j++){
    int r1;
    pTerm = pLoop->aLTerm[j];
    assert( pTerm!=0 );
    /* The following testcase is true for indices with redundant columns. 
    ** Ex: CREATE INDEX i1 ON t1(a,b,a); SELECT * FROM t1 WHERE a=0 AND b=0; */
    testcase( (pTerm->wtFlags & TERM_CODED)!=0 );
    testcase( pTerm->wtFlags & TERM_VIRTUAL );
    r1 = codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, regBase+j);
    if( r1!=regBase+j ){
      if( nReg==1 ){
        sqlite3ReleaseTempReg(pParse, regBase);
        regBase = r1;
      }else{
        sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
      }
    }
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_IN );
    if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
      Expr *pRight = pTerm->pExpr->pRight;
      if( (pTerm->wtFlags & TERM_IS)==0 && sqlite3ExprCanBeNull(pRight) ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
        VdbeCoverage(v);
      }
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){
          zAff[j] = SQLITE_AFF_NONE;
        }
        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){
          zAff[j] = SQLITE_AFF_NONE;
        }
      }
    }
  }
  *pzAff = zAff;
  return regBase;
}

#ifndef SQLITE_OMIT_EXPLAIN
/*
** This routine is a helper for explainIndexRange() below
**
** pStr holds the text of an expression that we are building up one term
** at a time.  This routine adds a new term to the end of the expression.
** Terms are separated by AND so add the "AND" text for second and subsequent
** terms only.
*/
static void explainAppendTerm(
  StrAccum *pStr,             /* The text expression being built */
  int iTerm,                  /* Index of this term.  First is zero */
  const char *zColumn,        /* Name of the column */
  const char *zOp             /* Name of the operator */
){
  if( iTerm ) sqlite3StrAccumAppend(pStr, " AND ", 5);
  sqlite3StrAccumAppendAll(pStr, zColumn);
  sqlite3StrAccumAppend(pStr, zOp, 1);
  sqlite3StrAccumAppend(pStr, "?", 1);
}

/*
** Argument pLevel describes a strategy for scanning table pTab. This 
** function appends text to pStr that describes the subset of table
** rows scanned by the strategy in the form of an SQL expression.
**
** For example, if the query:
**
**   SELECT * FROM t1 WHERE a=1 AND b>2;
**
** is run and there is an index on (a, b), then this function returns a
** string similar to:
**
**   "a=? AND b>?"
*/
static void explainIndexRange(StrAccum *pStr, WhereLoop *pLoop, Table *pTab){
  Index *pIndex = pLoop->u.btree.pIndex;
  u16 nEq = pLoop->u.btree.nEq;
  u16 nSkip = pLoop->nSkip;
  int i, j;
  Column *aCol = pTab->aCol;
  i16 *aiColumn = pIndex->aiColumn;

  if( nEq==0 && (pLoop->wsFlags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))==0 ) return;
  sqlite3StrAccumAppend(pStr, " (", 2);
  for(i=0; i<nEq; i++){
    char *z = aiColumn[i] < 0 ? "rowid" : aCol[aiColumn[i]].zName;
    if( i>=nSkip ){
      explainAppendTerm(pStr, i, z, "=");
    }else{
      if( i ) sqlite3StrAccumAppend(pStr, " AND ", 5);
      sqlite3XPrintf(pStr, 0, "ANY(%s)", z);
    }
  }

  j = i;
  if( pLoop->wsFlags&WHERE_BTM_LIMIT ){
    char *z = aiColumn[j] < 0 ? "rowid" : aCol[aiColumn[j]].zName;
    explainAppendTerm(pStr, i++, z, ">");
  }
  if( pLoop->wsFlags&WHERE_TOP_LIMIT ){
    char *z = aiColumn[j] < 0 ? "rowid" : aCol[aiColumn[j]].zName;
    explainAppendTerm(pStr, i, z, "<");
  }
  sqlite3StrAccumAppend(pStr, ")", 1);
}

/*
** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
** command, or if either SQLITE_DEBUG or SQLITE_ENABLE_STMT_SCANSTATUS was
** defined at compile-time. If it is not a no-op, a single OP_Explain opcode 
** is added to the output to describe the table scan strategy in pLevel.
**
** If an OP_Explain opcode is added to the VM, its address is returned.
** Otherwise, if no OP_Explain is coded, zero is returned.
*/
static int explainOneScan(
  Parse *pParse,                  /* Parse context */
  SrcList *pTabList,              /* Table list this loop refers to */
  WhereLevel *pLevel,             /* Scan to write OP_Explain opcode for */
  int iLevel,                     /* Value for "level" column of output */
  int iFrom,                      /* Value for "from" column of output */
  u16 wctrlFlags                  /* Flags passed to sqlite3WhereBegin() */
){
  int ret = 0;
#if !defined(SQLITE_DEBUG) && !defined(SQLITE_ENABLE_STMT_SCANSTATUS)
  if( pParse->explain==2 )
#endif
  {
    struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
    Vdbe *v = pParse->pVdbe;      /* VM being constructed */
    sqlite3 *db = pParse->db;     /* Database handle */
    int iId = pParse->iSelectId;  /* Select id (left-most output column) */
    int isSearch;                 /* True for a SEARCH. False for SCAN. */
    WhereLoop *pLoop;             /* The controlling WhereLoop object */
    u32 flags;                    /* Flags that describe this loop */
    char *zMsg;                   /* Text to add to EQP output */
    StrAccum str;                 /* EQP output string */
    char zBuf[100];               /* Initial space for EQP output string */

    pLoop = pLevel->pWLoop;
    flags = pLoop->wsFlags;
    if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_ONETABLE_ONLY) ) return 0;

    isSearch = (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0
            || ((flags&WHERE_VIRTUALTABLE)==0 && (pLoop->u.btree.nEq>0))
            || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX));

    sqlite3StrAccumInit(&str, db, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
    sqlite3StrAccumAppendAll(&str, isSearch ? "SEARCH" : "SCAN");
    if( pItem->pSelect ){
      sqlite3XPrintf(&str, 0, " SUBQUERY %d", pItem->iSelectId);
    }else{
      sqlite3XPrintf(&str, 0, " TABLE %s", pItem->zName);
    }

    if( pItem->zAlias ){
      sqlite3XPrintf(&str, 0, " AS %s", pItem->zAlias);
    }
    if( (flags & (WHERE_IPK|WHERE_VIRTUALTABLE))==0 ){
      const char *zFmt = 0;
      Index *pIdx;

      assert( pLoop->u.btree.pIndex!=0 );
      pIdx = pLoop->u.btree.pIndex;
      assert( !(flags&WHERE_AUTO_INDEX) || (flags&WHERE_IDX_ONLY) );
      if( !HasRowid(pItem->pTab) && IsPrimaryKeyIndex(pIdx) ){
        if( isSearch ){
          zFmt = "PRIMARY KEY";
        }
      }else if( flags & WHERE_PARTIALIDX ){
        zFmt = "AUTOMATIC PARTIAL COVERING INDEX";
      }else if( flags & WHERE_AUTO_INDEX ){
        zFmt = "AUTOMATIC COVERING INDEX";
      }else if( flags & WHERE_IDX_ONLY ){
        zFmt = "COVERING INDEX %s";
      }else{
        zFmt = "INDEX %s";
      }
      if( zFmt ){
        sqlite3StrAccumAppend(&str, " USING ", 7);
        sqlite3XPrintf(&str, 0, zFmt, pIdx->zName);
        explainIndexRange(&str, pLoop, pItem->pTab);
      }
    }else if( (flags & WHERE_IPK)!=0 && (flags & WHERE_CONSTRAINT)!=0 ){
      const char *zRange;
      if( flags&(WHERE_COLUMN_EQ|WHERE_COLUMN_IN) ){
        zRange = "(rowid=?)";
      }else if( (flags&WHERE_BOTH_LIMIT)==WHERE_BOTH_LIMIT ){
        zRange = "(rowid>? AND rowid<?)";
      }else if( flags&WHERE_BTM_LIMIT ){
        zRange = "(rowid>?)";
      }else{
        assert( flags&WHERE_TOP_LIMIT);
        zRange = "(rowid<?)";
      }
      sqlite3StrAccumAppendAll(&str, " USING INTEGER PRIMARY KEY ");
      sqlite3StrAccumAppendAll(&str, zRange);
    }
#ifndef SQLITE_OMIT_VIRTUALTABLE
    else if( (flags & WHERE_VIRTUALTABLE)!=0 ){
      sqlite3XPrintf(&str, 0, " VIRTUAL TABLE INDEX %d:%s",
                  pLoop->u.vtab.idxNum, pLoop->u.vtab.idxStr);
    }
#endif
#ifdef SQLITE_EXPLAIN_ESTIMATED_ROWS
    if( pLoop->nOut>=10 ){
      sqlite3XPrintf(&str, 0, " (~%llu rows)", sqlite3LogEstToInt(pLoop->nOut));
    }else{
      sqlite3StrAccumAppend(&str, " (~1 row)", 9);
    }
#endif
    zMsg = sqlite3StrAccumFinish(&str);
    ret = sqlite3VdbeAddOp4(v, OP_Explain, iId, iLevel, iFrom, zMsg,P4_DYNAMIC);
  }
  return ret;
}
#else
# define explainOneScan(u,v,w,x,y,z) 0
#endif /* SQLITE_OMIT_EXPLAIN */

#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
/*
** Configure the VM passed as the first argument with an
** sqlite3_stmt_scanstatus() entry corresponding to the scan used to 
** implement level pLvl. Argument pSrclist is a pointer to the FROM 
** clause that the scan reads data from.
**
** If argument addrExplain is not 0, it must be the address of an 
** OP_Explain instruction that describes the same loop.
*/
static void addScanStatus(
  Vdbe *v,                        /* Vdbe to add scanstatus entry to */
  SrcList *pSrclist,              /* FROM clause pLvl reads data from */
  WhereLevel *pLvl,               /* Level to add scanstatus() entry for */
  int addrExplain                 /* Address of OP_Explain (or 0) */
){
  const char *zObj = 0;
  WhereLoop *pLoop = pLvl->pWLoop;
  if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0  &&  pLoop->u.btree.pIndex!=0 ){
    zObj = pLoop->u.btree.pIndex->zName;
  }else{
    zObj = pSrclist->a[pLvl->iFrom].zName;
  }
  sqlite3VdbeScanStatus(
      v, addrExplain, pLvl->addrBody, pLvl->addrVisit, pLoop->nOut, zObj
  );
}
#else
# define addScanStatus(a, b, c, d) ((void)d)
#endif

/*
** If the most recently coded instruction is a constant range contraint
** that originated from the LIKE optimization, then change the P3 to be
** pLoop->iLikeRepCntr and set P5.
**
** The LIKE optimization trys to evaluate "x LIKE 'abc%'" as a range
** expression: "x>='ABC' AND x<'abd'".  But this requires that the range
** scan loop run twice, once for strings and a second time for BLOBs.
** The OP_String opcodes on the second pass convert the upper and lower
** bound string contants to blobs.  This routine makes the necessary changes
** to the OP_String opcodes for that to happen.
*/
static void whereLikeOptimizationStringFixup(
  Vdbe *v,                /* prepared statement under construction */
  WhereLevel *pLevel,     /* The loop that contains the LIKE operator */
  WhereTerm *pTerm        /* The upper or lower bound just coded */
){
  if( pTerm->wtFlags & TERM_LIKEOPT ){
    VdbeOp *pOp;
    assert( pLevel->iLikeRepCntr>0 );
    pOp = sqlite3VdbeGetOp(v, -1);
    assert( pOp!=0 );
    assert( pOp->opcode==OP_String8 
            || pTerm->pWC->pWInfo->pParse->db->mallocFailed );
    pOp->p3 = pLevel->iLikeRepCntr;
    pOp->p5 = 1;
  }
}

/*
** Generate code for the start of the iLevel-th loop in the WHERE clause
** implementation described by pWInfo.
*/
static Bitmask codeOneLoopStart(
  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
  int iLevel,          /* Which level of pWInfo->a[] should be coded */
  Bitmask notReady     /* Which tables are currently available */
){
  int j, k;            /* Loop counters */
  int iCur;            /* The VDBE cursor for the table */
  int addrNxt;         /* Where to jump to continue with the next IN case */
  int omitTable;       /* True if we use the index only */
  int bRev;            /* True if we need to scan in reverse order */
  WhereLevel *pLevel;  /* The where level to be coded */
  WhereLoop *pLoop;    /* The WhereLoop object being coded */
  WhereClause *pWC;    /* Decomposition of the entire WHERE clause */
  WhereTerm *pTerm;               /* A WHERE clause term */
  Parse *pParse;                  /* Parsing context */
  sqlite3 *db;                    /* Database connection */
  Vdbe *v;                        /* The prepared stmt under constructions */
  struct SrcList_item *pTabItem;  /* FROM clause term being coded */
  int addrBrk;                    /* Jump here to break out of the loop */
  int addrCont;                   /* Jump here to continue with next cycle */
  int iRowidReg = 0;        /* Rowid is stored in this register, if not zero */
  int iReleaseReg = 0;      /* Temp register to free before returning */

  pParse = pWInfo->pParse;
  v = pParse->pVdbe;
  pWC = &pWInfo->sWC;
  db = pParse->db;
  pLevel = &pWInfo->a[iLevel];
  pLoop = pLevel->pWLoop;
  pTabItem = &pWInfo->pTabList->a[pLevel->iFrom];
  iCur = pTabItem->iCursor;
  pLevel->notReady = notReady & ~getMask(&pWInfo->sMaskSet, iCur);
  bRev = (pWInfo->revMask>>iLevel)&1;
  omitTable = (pLoop->wsFlags & WHERE_IDX_ONLY)!=0 
           && (pWInfo->wctrlFlags & WHERE_FORCE_TABLE)==0;
  VdbeModuleComment((v, "Begin WHERE-loop%d: %s",iLevel,pTabItem->pTab->zName));

  /* Create labels for the "break" and "continue" instructions
  ** for the current loop.  Jump to addrBrk to break out of a loop.
  ** Jump to cont to go immediately to the next iteration of the
  ** loop.
  **
  ** When there is an IN operator, we also have a "addrNxt" label that
  ** means to continue with the next IN value combination.  When
  ** there are no IN operators in the constraints, the "addrNxt" label
  ** is the same as "addrBrk".
  */
  addrBrk = pLevel->addrBrk = pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
  addrCont = pLevel->addrCont = sqlite3VdbeMakeLabel(v);

  /* If this is the right table of a LEFT OUTER JOIN, allocate and
  ** initialize a memory cell that records if this table matches any
  ** row of the left table of the join.
  */
  if( pLevel->iFrom>0 && (pTabItem[0].jointype & JT_LEFT)!=0 ){
    pLevel->iLeftJoin = ++pParse->nMem;
    sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
    VdbeComment((v, "init LEFT JOIN no-match flag"));
  }

  /* Special case of a FROM clause subquery implemented as a co-routine */
  if( pTabItem->viaCoroutine ){
    int regYield = pTabItem->regReturn;
    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);
    pLevel->p2 =  sqlite3VdbeAddOp2(v, OP_Yield, regYield, addrBrk);
    VdbeCoverage(v);
    VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->zName));
    pLevel->op = OP_Goto;
  }else

#ifndef SQLITE_OMIT_VIRTUALTABLE
  if(  (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
    /* Case 1:  The table is a virtual-table.  Use the VFilter and VNext
    **          to access the data.
    */
    int iReg;   /* P3 Value for OP_VFilter */
    int addrNotFound;
    int nConstraint = pLoop->nLTerm;

    sqlite3ExprCachePush(pParse);
    iReg = sqlite3GetTempRange(pParse, nConstraint+2);
    addrNotFound = pLevel->addrBrk;
    for(j=0; j<nConstraint; j++){
      int iTarget = iReg+j+2;
      pTerm = pLoop->aLTerm[j];
      if( pTerm==0 ) continue;
      if( pTerm->eOperator & WO_IN ){
        codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, iTarget);
        addrNotFound = pLevel->addrNxt;
      }else{
        sqlite3ExprCode(pParse, pTerm->pExpr->pRight, iTarget);
      }
    }
    sqlite3VdbeAddOp2(v, OP_Integer, pLoop->u.vtab.idxNum, iReg);
    sqlite3VdbeAddOp2(v, OP_Integer, nConstraint, iReg+1);
    sqlite3VdbeAddOp4(v, OP_VFilter, iCur, addrNotFound, iReg,
                      pLoop->u.vtab.idxStr,
                      pLoop->u.vtab.needFree ? P4_MPRINTF : P4_STATIC);
    VdbeCoverage(v);
    pLoop->u.vtab.needFree = 0;
    for(j=0; j<nConstraint && j<16; j++){
      if( (pLoop->u.vtab.omitMask>>j)&1 ){
        disableTerm(pLevel, pLoop->aLTerm[j]);
      }
    }
    pLevel->op = OP_VNext;
    pLevel->p1 = iCur;
    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
    sqlite3ReleaseTempRange(pParse, iReg, nConstraint+2);
    sqlite3ExprCachePop(pParse);
  }else
#endif /* SQLITE_OMIT_VIRTUALTABLE */

  if( (pLoop->wsFlags & WHERE_IPK)!=0
   && (pLoop->wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_EQ))!=0
  ){
    /* Case 2:  We can directly reference a single row using an
    **          equality comparison against the ROWID field.  Or
    **          we reference multiple rows using a "rowid IN (...)"
    **          construct.
    */
    assert( pLoop->u.btree.nEq==1 );
    pTerm = pLoop->aLTerm[0];
    assert( pTerm!=0 );
    assert( pTerm->pExpr!=0 );
    assert( omitTable==0 );
    testcase( pTerm->wtFlags & TERM_VIRTUAL );
    iReleaseReg = ++pParse->nMem;
    iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, 0, bRev, iReleaseReg);
    if( iRowidReg!=iReleaseReg ) sqlite3ReleaseTempReg(pParse, iReleaseReg);
    addrNxt = pLevel->addrNxt;
    sqlite3VdbeAddOp2(v, OP_MustBeInt, iRowidReg, addrNxt); VdbeCoverage(v);
    sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addrNxt, iRowidReg);
    VdbeCoverage(v);
    sqlite3ExprCacheAffinityChange(pParse, iRowidReg, 1);
    sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
    VdbeComment((v, "pk"));
    pLevel->op = OP_Noop;
  }else if( (pLoop->wsFlags & WHERE_IPK)!=0
         && (pLoop->wsFlags & WHERE_COLUMN_RANGE)!=0
  ){
    /* Case 3:  We have an inequality comparison against the ROWID field.
    */
    int testOp = OP_Noop;
    int start;
    int memEndValue = 0;
    WhereTerm *pStart, *pEnd;

    assert( omitTable==0 );
    j = 0;
    pStart = pEnd = 0;
    if( pLoop->wsFlags & WHERE_BTM_LIMIT ) pStart = pLoop->aLTerm[j++];
    if( pLoop->wsFlags & WHERE_TOP_LIMIT ) pEnd = pLoop->aLTerm[j++];
    assert( pStart!=0 || pEnd!=0 );
    if( bRev ){
      pTerm = pStart;
      pStart = pEnd;
      pEnd = pTerm;
    }
    if( pStart ){
      Expr *pX;             /* The expression that defines the start bound */
      int r1, rTemp;        /* Registers for holding the start boundary */

      /* The following constant maps TK_xx codes into corresponding 
      ** seek opcodes.  It depends on a particular ordering of TK_xx
      */
      const u8 aMoveOp[] = {
           /* TK_GT */  OP_SeekGT,
           /* TK_LE */  OP_SeekLE,
           /* TK_LT */  OP_SeekLT,
           /* TK_GE */  OP_SeekGE
      };
      assert( TK_LE==TK_GT+1 );      /* Make sure the ordering.. */
      assert( TK_LT==TK_GT+2 );      /*  ... of the TK_xx values... */
      assert( TK_GE==TK_GT+3 );      /*  ... is correcct. */

      assert( (pStart->wtFlags & TERM_VNULL)==0 );
      testcase( pStart->wtFlags & TERM_VIRTUAL );
      pX = pStart->pExpr;
      assert( pX!=0 );
      testcase( pStart->leftCursor!=iCur ); /* transitive constraints */
      r1 = sqlite3ExprCodeTemp(pParse, pX->pRight, &rTemp);
      sqlite3VdbeAddOp3(v, aMoveOp[pX->op-TK_GT], iCur, addrBrk, r1);
      VdbeComment((v, "pk"));
      VdbeCoverageIf(v, pX->op==TK_GT);
      VdbeCoverageIf(v, pX->op==TK_LE);
      VdbeCoverageIf(v, pX->op==TK_LT);
      VdbeCoverageIf(v, pX->op==TK_GE);
      sqlite3ExprCacheAffinityChange(pParse, r1, 1);
      sqlite3ReleaseTempReg(pParse, rTemp);
      disableTerm(pLevel, pStart);
    }else{
      sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, addrBrk);
      VdbeCoverageIf(v, bRev==0);
      VdbeCoverageIf(v, bRev!=0);
    }
    if( pEnd ){
      Expr *pX;
      pX = pEnd->pExpr;
      assert( pX!=0 );
      assert( (pEnd->wtFlags & TERM_VNULL)==0 );
      testcase( pEnd->leftCursor!=iCur ); /* Transitive constraints */
      testcase( pEnd->wtFlags & TERM_VIRTUAL );
      memEndValue = ++pParse->nMem;
      sqlite3ExprCode(pParse, pX->pRight, memEndValue);
      if( pX->op==TK_LT || pX->op==TK_GT ){
        testOp = bRev ? OP_Le : OP_Ge;
      }else{
        testOp = bRev ? OP_Lt : OP_Gt;
      }
      disableTerm(pLevel, pEnd);
    }
    start = sqlite3VdbeCurrentAddr(v);
    pLevel->op = bRev ? OP_Prev : OP_Next;
    pLevel->p1 = iCur;
    pLevel->p2 = start;
    assert( pLevel->p5==0 );
    if( testOp!=OP_Noop ){
      iRowidReg = ++pParse->nMem;
      sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg);
      sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
      sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, iRowidReg);
      VdbeCoverageIf(v, testOp==OP_Le);
      VdbeCoverageIf(v, testOp==OP_Lt);
      VdbeCoverageIf(v, testOp==OP_Ge);
      VdbeCoverageIf(v, testOp==OP_Gt);
      sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL);
    }
  }else if( pLoop->wsFlags & WHERE_INDEXED ){
    /* Case 4: A scan using an index.
    **
    **         The WHERE clause may contain zero or more equality 
    **         terms ("==" or "IN" operators) that refer to the N
    **         left-most columns of the index. It may also contain
    **         inequality constraints (>, <, >= or <=) on the indexed
    **         column that immediately follows the N equalities. Only 
    **         the right-most column can be an inequality - the rest must
    **         use the "==" and "IN" operators. For example, if the 
    **         index is on (x,y,z), then the following clauses are all 
    **         optimized:
    **
    **            x=5
    **            x=5 AND y=10
    **            x=5 AND y<10
    **            x=5 AND y>5 AND y<10
    **            x=5 AND y=5 AND z<=10
    **
    **         The z<10 term of the following cannot be used, only
    **         the x=5 term:
    **
    **            x=5 AND z<10
    **
    **         N may be zero if there are inequality constraints.
    **         If there are no inequality constraints, then N is at
    **         least one.
    **
    **         This case is also used when there are no WHERE clause
    **         constraints but an index is selected anyway, in order
    **         to force the output order to conform to an ORDER BY.
    */  
    static const u8 aStartOp[] = {
      0,
      0,
      OP_Rewind,           /* 2: (!start_constraints && startEq &&  !bRev) */
      OP_Last,             /* 3: (!start_constraints && startEq &&   bRev) */
      OP_SeekGT,           /* 4: (start_constraints  && !startEq && !bRev) */
      OP_SeekLT,           /* 5: (start_constraints  && !startEq &&  bRev) */
      OP_SeekGE,           /* 6: (start_constraints  &&  startEq && !bRev) */
      OP_SeekLE            /* 7: (start_constraints  &&  startEq &&  bRev) */
    };
    static const u8 aEndOp[] = {
      OP_IdxGE,            /* 0: (end_constraints && !bRev && !endEq) */
      OP_IdxGT,            /* 1: (end_constraints && !bRev &&  endEq) */
      OP_IdxLE,            /* 2: (end_constraints &&  bRev && !endEq) */
      OP_IdxLT,            /* 3: (end_constraints &&  bRev &&  endEq) */
    };
    u16 nEq = pLoop->u.btree.nEq;     /* Number of == or IN terms */
    int regBase;                 /* Base register holding constraint values */
    WhereTerm *pRangeStart = 0;  /* Inequality constraint at range start */
    WhereTerm *pRangeEnd = 0;    /* Inequality constraint at range end */
    int startEq;                 /* True if range start uses ==, >= or <= */
    int endEq;                   /* True if range end uses ==, >= or <= */
    int start_constraints;       /* Start of range is constrained */
    int nConstraint;             /* Number of constraint terms */
    Index *pIdx;                 /* The index we will be using */
    int iIdxCur;                 /* The VDBE cursor for the index */
    int nExtraReg = 0;           /* Number of extra registers needed */
    int op;                      /* Instruction opcode */
    char *zStartAff;             /* Affinity for start of range constraint */
    char cEndAff = 0;            /* Affinity for end of range constraint */
    u8 bSeekPastNull = 0;        /* True to seek past initial nulls */
    u8 bStopAtNull = 0;          /* Add condition to terminate at NULLs */

    pIdx = pLoop->u.btree.pIndex;
    iIdxCur = pLevel->iIdxCur;
    assert( nEq>=pLoop->nSkip );

    /* If this loop satisfies a sort order (pOrderBy) request that 
    ** was passed to this function to implement a "SELECT min(x) ..." 
    ** query, then the caller will only allow the loop to run for
    ** a single iteration. This means that the first row returned
    ** should not have a NULL value stored in 'x'. If column 'x' is
    ** the first one after the nEq equality constraints in the index,
    ** this requires some special handling.
    */
    assert( pWInfo->pOrderBy==0
         || pWInfo->pOrderBy->nExpr==1
         || (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0 );
    if( (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)!=0
     && pWInfo->nOBSat>0
     && (pIdx->nKeyCol>nEq)
    ){
      assert( pLoop->nSkip==0 );
      bSeekPastNull = 1;
      nExtraReg = 1;
    }

    /* Find any inequality constraint terms for the start and end 
    ** of the range. 
    */
    j = nEq;
    if( pLoop->wsFlags & WHERE_BTM_LIMIT ){
      pRangeStart = pLoop->aLTerm[j++];
      nExtraReg = 1;
      /* Like optimization range constraints always occur in pairs */
      assert( (pRangeStart->wtFlags & TERM_LIKEOPT)==0 || 
              (pLoop->wsFlags & WHERE_TOP_LIMIT)!=0 );
    }
    if( pLoop->wsFlags & WHERE_TOP_LIMIT ){
      pRangeEnd = pLoop->aLTerm[j++];
      nExtraReg = 1;
      if( (pRangeEnd->wtFlags & TERM_LIKEOPT)!=0 ){
        assert( pRangeStart!=0 );                     /* LIKE opt constraints */
        assert( pRangeStart->wtFlags & TERM_LIKEOPT );   /* occur in pairs */
        pLevel->iLikeRepCntr = ++pParse->nMem;
        testcase( bRev );
        testcase( pIdx->aSortOrder[nEq]==SQLITE_SO_DESC );
        sqlite3VdbeAddOp2(v, OP_Integer,
                          bRev ^ (pIdx->aSortOrder[nEq]==SQLITE_SO_DESC),
                          pLevel->iLikeRepCntr);
        VdbeComment((v, "LIKE loop counter"));
        pLevel->addrLikeRep = sqlite3VdbeCurrentAddr(v);
      }
      if( pRangeStart==0
       && (j = pIdx->aiColumn[nEq])>=0 
       && pIdx->pTable->aCol[j].notNull==0
      ){
        bSeekPastNull = 1;
      }
    }
    assert( pRangeEnd==0 || (pRangeEnd->wtFlags & TERM_VNULL)==0 );

    /* Generate code to evaluate all constraint terms using == or IN
    ** and store the values of those terms in an array of registers
    ** starting at regBase.
    */
    regBase = codeAllEqualityTerms(pParse,pLevel,bRev,nExtraReg,&zStartAff);
    assert( zStartAff==0 || sqlite3Strlen30(zStartAff)>=nEq );
    if( zStartAff ) cEndAff = zStartAff[nEq];
    addrNxt = pLevel->addrNxt;

    /* If we are doing a reverse order scan on an ascending index, or
    ** a forward order scan on a descending index, interchange the 
    ** start and end terms (pRangeStart and pRangeEnd).
    */
    if( (nEq<pIdx->nKeyCol && bRev==(pIdx->aSortOrder[nEq]==SQLITE_SO_ASC))
     || (bRev && pIdx->nKeyCol==nEq)
    ){
      SWAP(WhereTerm *, pRangeEnd, pRangeStart);
      SWAP(u8, bSeekPastNull, bStopAtNull);
    }

    testcase( pRangeStart && (pRangeStart->eOperator & WO_LE)!=0 );
    testcase( pRangeStart && (pRangeStart->eOperator & WO_GE)!=0 );
    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_LE)!=0 );
    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_GE)!=0 );
    startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE);
    endEq =   !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE);
    start_constraints = pRangeStart || nEq>0;

    /* Seek the index cursor to the start of the range. */
    nConstraint = nEq;
    if( pRangeStart ){
      Expr *pRight = pRangeStart->pExpr->pRight;
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeStart);
      if( (pRangeStart->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( zStartAff ){
        if( sqlite3CompareAffinity(pRight, zStartAff[nEq])==SQLITE_AFF_NONE){
          /* Since the comparison is to be performed with no conversions
          ** applied to the operands, set the affinity to apply to pRight to 
          ** SQLITE_AFF_NONE.  */
          zStartAff[nEq] = SQLITE_AFF_NONE;
        }
        if( sqlite3ExprNeedsNoAffinityChange(pRight, zStartAff[nEq]) ){
          zStartAff[nEq] = SQLITE_AFF_NONE;
        }
      }  
      nConstraint++;
      testcase( pRangeStart->wtFlags & TERM_VIRTUAL );
    }else if( bSeekPastNull ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
      nConstraint++;
      startEq = 0;
      start_constraints = 1;
    }
    codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff);
    op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
    assert( op!=0 );
    sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
    VdbeCoverage(v);
    VdbeCoverageIf(v, op==OP_Rewind);  testcase( op==OP_Rewind );
    VdbeCoverageIf(v, op==OP_Last);    testcase( op==OP_Last );
    VdbeCoverageIf(v, op==OP_SeekGT);  testcase( op==OP_SeekGT );
    VdbeCoverageIf(v, op==OP_SeekGE);  testcase( op==OP_SeekGE );
    VdbeCoverageIf(v, op==OP_SeekLE);  testcase( op==OP_SeekLE );
    VdbeCoverageIf(v, op==OP_SeekLT);  testcase( op==OP_SeekLT );

    /* Load the value for the inequality constraint at the end of the
    ** range (if any).
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;
      sqlite3ExprCacheRemove(pParse, regBase+nEq, 1);
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeEnd);
      if( (pRangeEnd->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( sqlite3CompareAffinity(pRight, cEndAff)!=SQLITE_AFF_NONE
       && !sqlite3ExprNeedsNoAffinityChange(pRight, cEndAff)
      ){
        codeApplyAffinity(pParse, regBase+nEq, 1, &cEndAff);
      }
      nConstraint++;
      testcase( pRangeEnd->wtFlags & TERM_VIRTUAL );
    }else if( bStopAtNull ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
      endEq = 0;
      nConstraint++;
    }
    sqlite3DbFree(db, zStartAff);

    /* Top of the loop body */
    pLevel->p2 = sqlite3VdbeCurrentAddr(v);

    /* Check if the index cursor is past the end of the range. */
    if( nConstraint ){
      op = aEndOp[bRev*2 + endEq];
      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
      testcase( op==OP_IdxGT );  VdbeCoverageIf(v, op==OP_IdxGT );
      testcase( op==OP_IdxGE );  VdbeCoverageIf(v, op==OP_IdxGE );
      testcase( op==OP_IdxLT );  VdbeCoverageIf(v, op==OP_IdxLT );
      testcase( op==OP_IdxLE );  VdbeCoverageIf(v, op==OP_IdxLE );
    }

    /* Seek the table cursor, if required */
    disableTerm(pLevel, pRangeStart);
    disableTerm(pLevel, pRangeEnd);
    if( omitTable ){
      /* pIdx is a covering index.  No need to access the main table. */
    }else if( HasRowid(pIdx->pTable) ){
      iRowidReg = ++pParse->nMem;
      sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, iRowidReg);
      sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
      sqlite3VdbeAddOp2(v, OP_Seek, iCur, iRowidReg);  /* Deferred seek */
    }else if( iCur!=iIdxCur ){
      Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable);
      iRowidReg = sqlite3GetTempRange(pParse, pPk->nKeyCol);
      for(j=0; j<pPk->nKeyCol; j++){
        k = sqlite3ColumnOfIndex(pIdx, pPk->aiColumn[j]);
        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k, iRowidReg+j);
      }
      sqlite3VdbeAddOp4Int(v, OP_NotFound, iCur, addrCont,
                           iRowidReg, pPk->nKeyCol); VdbeCoverage(v);
    }

    /* Record the instruction used to terminate the loop. Disable 
    ** WHERE clause terms made redundant by the index range scan.
    */
    if( pLoop->wsFlags & WHERE_ONEROW ){
      pLevel->op = OP_Noop;
    }else if( bRev ){
      pLevel->op = OP_Prev;
    }else{
      pLevel->op = OP_Next;
    }
    pLevel->p1 = iIdxCur;
    pLevel->p3 = (pLoop->wsFlags&WHERE_UNQ_WANTED)!=0 ? 1:0;
    if( (pLoop->wsFlags & WHERE_CONSTRAINT)==0 ){
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }else{
      assert( pLevel->p5==0 );
    }
  }else

#ifndef SQLITE_OMIT_OR_OPTIMIZATION
  if( pLoop->wsFlags & WHERE_MULTI_OR ){
    /* Case 5:  Two or more separately indexed terms connected by OR
    **
    ** Example:
    **
    **   CREATE TABLE t1(a,b,c,d);
    **   CREATE INDEX i1 ON t1(a);
    **   CREATE INDEX i2 ON t1(b);
    **   CREATE INDEX i3 ON t1(c);
    **
    **   SELECT * FROM t1 WHERE a=5 OR b=7 OR (c=11 AND d=13)
    **
    ** In the example, there are three indexed terms connected by OR.
    ** The top of the loop looks like this:
    **
    **          Null       1                # Zero the rowset in reg 1
    **
    ** Then, for each indexed term, the following. The arguments to
    ** RowSetTest are such that the rowid of the current row is inserted
    ** into the RowSet. If it is already present, control skips the
    ** Gosub opcode and jumps straight to the code generated by WhereEnd().
    **
    **        sqlite3WhereBegin(<term>)
    **          RowSetTest                  # Insert rowid into rowset
    **          Gosub      2 A
    **        sqlite3WhereEnd()
    **
    ** Following the above, code to terminate the loop. Label A, the target
    ** of the Gosub above, jumps to the instruction right after the Goto.
    **
    **          Null       1                # Zero the rowset in reg 1
    **          Goto       B                # The loop is finished.
    **
    **       A: <loop body>                 # Return data, whatever.
    **
    **          Return     2                # Jump back to the Gosub
    **
    **       B: <after the loop>
    **
    ** Added 2014-05-26: If the table is a WITHOUT ROWID table, then
    ** use an ephemeral index instead of a RowSet to record the primary
    ** keys of the rows we have already seen.
    **
    */
    WhereClause *pOrWc;    /* The OR-clause broken out into subterms */
    SrcList *pOrTab;       /* Shortened table list or OR-clause generation */
    Index *pCov = 0;             /* Potential covering index (or NULL) */
    int iCovCur = pParse->nTab++;  /* Cursor used for index scans (if any) */

    int regReturn = ++pParse->nMem;           /* Register used with OP_Gosub */
    int regRowset = 0;                        /* Register for RowSet object */
    int regRowid = 0;                         /* Register holding rowid */
    int iLoopBody = sqlite3VdbeMakeLabel(v);  /* Start of loop body */
    int iRetInit;                             /* Address of regReturn init */
    int untestedTerms = 0;             /* Some terms not completely tested */
    int ii;                            /* Loop counter */
    u16 wctrlFlags;                    /* Flags for sub-WHERE clause */
    Expr *pAndExpr = 0;                /* An ".. AND (...)" expression */
    Table *pTab = pTabItem->pTab;
   
    pTerm = pLoop->aLTerm[0];
    assert( pTerm!=0 );
    assert( pTerm->eOperator & WO_OR );
    assert( (pTerm->wtFlags & TERM_ORINFO)!=0 );
    pOrWc = &pTerm->u.pOrInfo->wc;
    pLevel->op = OP_Return;
    pLevel->p1 = regReturn;

    /* Set up a new SrcList in pOrTab containing the table being scanned
    ** by this loop in the a[0] slot and all notReady tables in a[1..] slots.
    ** This becomes the SrcList in the recursive call to sqlite3WhereBegin().
    */
    if( pWInfo->nLevel>1 ){
      int nNotReady;                 /* The number of notReady tables */
      struct SrcList_item *origSrc;     /* Original list of tables */
      nNotReady = pWInfo->nLevel - iLevel - 1;
      pOrTab = sqlite3StackAllocRaw(db,
                            sizeof(*pOrTab)+ nNotReady*sizeof(pOrTab->a[0]));
      if( pOrTab==0 ) return notReady;
      pOrTab->nAlloc = (u8)(nNotReady + 1);
      pOrTab->nSrc = pOrTab->nAlloc;
      memcpy(pOrTab->a, pTabItem, sizeof(*pTabItem));
      origSrc = pWInfo->pTabList->a;
      for(k=1; k<=nNotReady; k++){
        memcpy(&pOrTab->a[k], &origSrc[pLevel[k].iFrom], sizeof(pOrTab->a[k]));
      }
    }else{
      pOrTab = pWInfo->pTabList;
    }

    /* Initialize the rowset register to contain NULL. An SQL NULL is 
    ** equivalent to an empty rowset.  Or, create an ephemeral index
    ** capable of holding primary keys in the case of a WITHOUT ROWID.
    **
    ** Also initialize regReturn to contain the address of the instruction 
    ** immediately following the OP_Return at the bottom of the loop. This
    ** is required in a few obscure LEFT JOIN cases where control jumps
    ** over the top of the loop into the body of it. In this case the 
    ** correct response for the end-of-loop code (the OP_Return) is to 
    ** fall through to the next instruction, just as an OP_Next does if
    ** called on an uninitialized cursor.
    */
    if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
      if( HasRowid(pTab) ){
        regRowset = ++pParse->nMem;
        sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset);
      }else{
        Index *pPk = sqlite3PrimaryKeyIndex(pTab);
        regRowset = pParse->nTab++;
        sqlite3VdbeAddOp2(v, OP_OpenEphemeral, regRowset, pPk->nKeyCol);
        sqlite3VdbeSetP4KeyInfo(pParse, pPk);
      }
      regRowid = ++pParse->nMem;
    }
    iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);

    /* If the original WHERE clause is z of the form:  (x1 OR x2 OR ...) AND y
    ** Then for every term xN, evaluate as the subexpression: xN AND z
    ** That way, terms in y that are factored into the disjunction will
    ** be picked up by the recursive calls to sqlite3WhereBegin() below.
    **
    ** Actually, each subexpression is converted to "xN AND w" where w is
    ** the "interesting" terms of z - terms that did not originate in the
    ** ON or USING clause of a LEFT JOIN, and terms that are usable as 
    ** indices.
    **
    ** This optimization also only applies if the (x1 OR x2 OR ...) term
    ** is not contained in the ON clause of a LEFT JOIN.
    ** See ticket http://www.sqlite.org/src/info/f2369304e4
    */
    if( pWC->nTerm>1 ){
      int iTerm;
      for(iTerm=0; iTerm<pWC->nTerm; iTerm++){
        Expr *pExpr = pWC->a[iTerm].pExpr;
        if( &pWC->a[iTerm] == pTerm ) continue;
        if( ExprHasProperty(pExpr, EP_FromJoin) ) continue;
        if( (pWC->a[iTerm].wtFlags & TERM_VIRTUAL)!=0 ) continue;
        if( (pWC->a[iTerm].eOperator & WO_ALL)==0 ) continue;
        testcase( pWC->a[iTerm].wtFlags & TERM_ORINFO );
        pExpr = sqlite3ExprDup(db, pExpr, 0);
        pAndExpr = sqlite3ExprAnd(db, pAndExpr, pExpr);
      }
      if( pAndExpr ){
        pAndExpr = sqlite3PExpr(pParse, TK_AND, 0, pAndExpr, 0);
      }
    }

    /* Run a separate WHERE clause for each term of the OR clause.  After
    ** eliminating duplicates from other WHERE clauses, the action for each
    ** sub-WHERE clause is to to invoke the main loop body as a subroutine.
    */
    wctrlFlags =  WHERE_OMIT_OPEN_CLOSE
                | WHERE_FORCE_TABLE
                | WHERE_ONETABLE_ONLY
                | WHERE_NO_AUTOINDEX;
    for(ii=0; ii<pOrWc->nTerm; ii++){
      WhereTerm *pOrTerm = &pOrWc->a[ii];
      if( pOrTerm->leftCursor==iCur || (pOrTerm->eOperator & WO_AND)!=0 ){
        WhereInfo *pSubWInfo;           /* Info for single OR-term scan */
        Expr *pOrExpr = pOrTerm->pExpr; /* Current OR clause term */
        int j1 = 0;                     /* Address of jump operation */
        if( pAndExpr && !ExprHasProperty(pOrExpr, EP_FromJoin) ){
          pAndExpr->pLeft = pOrExpr;
          pOrExpr = pAndExpr;
        }
        /* Loop through table entries that match term pOrTerm. */
        WHERETRACE(0xffff, ("Subplan for OR-clause:\n"));
        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0,
                                      wctrlFlags, iCovCur);
        assert( pSubWInfo || pParse->nErr || db->mallocFailed );
        if( pSubWInfo ){
          WhereLoop *pSubLoop;
          int addrExplain = explainOneScan(
              pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0
          );
          addScanStatus(v, pOrTab, &pSubWInfo->a[0], addrExplain);

          /* This is the sub-WHERE clause body.  First skip over
          ** duplicate rows from prior sub-WHERE clauses, and record the
          ** rowid (or PRIMARY KEY) for the current row so that the same
          ** row will be skipped in subsequent sub-WHERE clauses.
          */
          if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
            int r;
            int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
            if( HasRowid(pTab) ){
              r = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, regRowid, 0);
              j1 = sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset, 0, r,iSet);
              VdbeCoverage(v);
            }else{
              Index *pPk = sqlite3PrimaryKeyIndex(pTab);
              int nPk = pPk->nKeyCol;
              int iPk;

              /* Read the PK into an array of temp registers. */
              r = sqlite3GetTempRange(pParse, nPk);
              for(iPk=0; iPk<nPk; iPk++){
                int iCol = pPk->aiColumn[iPk];
                sqlite3ExprCodeGetColumn(pParse, pTab, iCol, iCur, r+iPk, 0);
              }

              /* Check if the temp table already contains this key. If so,
              ** the row has already been included in the result set and
              ** can be ignored (by jumping past the Gosub below). Otherwise,
              ** insert the key into the temp table and proceed with processing
              ** the row.
              **
              ** Use some of the same optimizations as OP_RowSetTest: If iSet
              ** is zero, assume that the key cannot already be present in
              ** the temp table. And if iSet is -1, assume that there is no 
              ** need to insert the key into the temp table, as it will never 
              ** be tested for.  */ 
              if( iSet ){
                j1 = sqlite3VdbeAddOp4Int(v, OP_Found, regRowset, 0, r, nPk);
                VdbeCoverage(v);
              }
              if( iSet>=0 ){
                sqlite3VdbeAddOp3(v, OP_MakeRecord, r, nPk, regRowid);
                sqlite3VdbeAddOp3(v, OP_IdxInsert, regRowset, regRowid, 0);
                if( iSet ) sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
              }

              /* Release the array of temp registers */
              sqlite3ReleaseTempRange(pParse, r, nPk);
            }
          }

          /* Invoke the main loop body as a subroutine */
          sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody);

          /* Jump here (skipping the main loop body subroutine) if the
          ** current sub-WHERE row is a duplicate from prior sub-WHEREs. */
          if( j1 ) sqlite3VdbeJumpHere(v, j1);

          /* The pSubWInfo->untestedTerms flag means that this OR term
          ** contained one or more AND term from a notReady table.  The
          ** terms from the notReady table could not be tested and will
          ** need to be tested later.
          */
          if( pSubWInfo->untestedTerms ) untestedTerms = 1;

          /* If all of the OR-connected terms are optimized using the same
          ** index, and the index is opened using the same cursor number
          ** by each call to sqlite3WhereBegin() made by this loop, it may
          ** be possible to use that index as a covering index.
          **
          ** If the call to sqlite3WhereBegin() above resulted in a scan that
          ** uses an index, and this is either the first OR-connected term
          ** processed or the index is the same as that used by all previous
          ** terms, set pCov to the candidate covering index. Otherwise, set 
          ** pCov to NULL to indicate that no candidate covering index will 
          ** be available.
          */
          pSubLoop = pSubWInfo->a[0].pWLoop;
          assert( (pSubLoop->wsFlags & WHERE_AUTO_INDEX)==0 );
          if( (pSubLoop->wsFlags & WHERE_INDEXED)!=0
           && (ii==0 || pSubLoop->u.btree.pIndex==pCov)
           && (HasRowid(pTab) || !IsPrimaryKeyIndex(pSubLoop->u.btree.pIndex))
          ){
            assert( pSubWInfo->a[0].iIdxCur==iCovCur );
            pCov = pSubLoop->u.btree.pIndex;
            wctrlFlags |= WHERE_REOPEN_IDX;
          }else{
            pCov = 0;
          }

          /* Finish the loop through table entries that match term pOrTerm. */
          sqlite3WhereEnd(pSubWInfo);
        }
      }
    }
    pLevel->u.pCovidx = pCov;
    if( pCov ) pLevel->iIdxCur = iCovCur;
    if( pAndExpr ){
      pAndExpr->pLeft = 0;
      sqlite3ExprDelete(db, pAndExpr);
    }
    sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
    sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk);
    sqlite3VdbeResolveLabel(v, iLoopBody);

    if( pWInfo->nLevel>1 ) sqlite3StackFree(db, pOrTab);
    if( !untestedTerms ) disableTerm(pLevel, pTerm);
  }else
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */

  {
    /* Case 6:  There is no usable index.  We must do a complete
    **          scan of the entire table.
    */
    static const u8 aStep[] = { OP_Next, OP_Prev };
    static const u8 aStart[] = { OP_Rewind, OP_Last };
    assert( bRev==0 || bRev==1 );
    if( pTabItem->isRecursive ){
      /* Tables marked isRecursive have only a single row that is stored in
      ** a pseudo-cursor.  No need to Rewind or Next such cursors. */
      pLevel->op = OP_Noop;
    }else{
      pLevel->op = aStep[bRev];
      pLevel->p1 = iCur;
      pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk);
      VdbeCoverageIf(v, bRev==0);
      VdbeCoverageIf(v, bRev!=0);
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }
  }

#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
  pLevel->addrVisit = sqlite3VdbeCurrentAddr(v);
#endif

  /* Insert code to test every subexpression that can be completely
  ** computed using the current set of tables.
  */
  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
    Expr *pE;
    int skipLikeAddr = 0;
    testcase( pTerm->wtFlags & TERM_VIRTUAL );
    testcase( pTerm->wtFlags & TERM_CODED );
    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
    if( (pTerm->prereqAll & pLevel->notReady)!=0 ){
      testcase( pWInfo->untestedTerms==0
               && (pWInfo->wctrlFlags & WHERE_ONETABLE_ONLY)!=0 );
      pWInfo->untestedTerms = 1;
      continue;
    }
    pE = pTerm->pExpr;
    assert( pE!=0 );
    if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
      continue;
    }
    if( pTerm->wtFlags & TERM_LIKECOND ){
      assert( pLevel->iLikeRepCntr>0 );
      skipLikeAddr = sqlite3VdbeAddOp1(v, OP_IfNot, pLevel->iLikeRepCntr);
      VdbeCoverage(v);
    }
    sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL);
    if( skipLikeAddr ) sqlite3VdbeJumpHere(v, skipLikeAddr);
    pTerm->wtFlags |= TERM_CODED;
  }

  /* Insert code to test for implied constraints based on transitivity
  ** of the "==" operator.
  **
  ** Example: If the WHERE clause contains "t1.a=t2.b" and "t2.b=123"
  ** and we are coding the t1 loop and the t2 loop has not yet coded,
  ** then we cannot use the "t1.a=t2.b" constraint, but we can code
  ** the implied "t1.a=123" constraint.
  */
  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
    Expr *pE, *pEAlt;
    WhereTerm *pAlt;
    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
    if( (pTerm->eOperator & (WO_EQ|WO_IS))==0 ) continue;
    if( (pTerm->eOperator & WO_EQUIV)==0 ) continue;
    if( pTerm->leftCursor!=iCur ) continue;
    if( pLevel->iLeftJoin ) continue;
    pE = pTerm->pExpr;
    assert( !ExprHasProperty(pE, EP_FromJoin) );
    assert( (pTerm->prereqRight & pLevel->notReady)!=0 );
    pAlt = findTerm(pWC, iCur, pTerm->u.leftColumn, notReady,
                    WO_EQ|WO_IN|WO_IS, 0);
    if( pAlt==0 ) continue;
    if( pAlt->wtFlags & (TERM_CODED) ) continue;
    testcase( pAlt->eOperator & WO_EQ );
    testcase( pAlt->eOperator & WO_IS );
    testcase( pAlt->eOperator & WO_IN );
    VdbeModuleComment((v, "begin transitive constraint"));
    pEAlt = sqlite3StackAllocRaw(db, sizeof(*pEAlt));
    if( pEAlt ){
      *pEAlt = *pAlt->pExpr;
      pEAlt->pLeft = pE->pLeft;
      sqlite3ExprIfFalse(pParse, pEAlt, addrCont, SQLITE_JUMPIFNULL);
      sqlite3StackFree(db, pEAlt);
    }
  }

  /* For a LEFT OUTER JOIN, generate code that will record the fact that
  ** at least one row of the right table has matched the left table.  
  */
  if( pLevel->iLeftJoin ){
    pLevel->addrFirst = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->iLeftJoin);
    VdbeComment((v, "record LEFT JOIN hit"));
    sqlite3ExprCacheClear(pParse);
    for(pTerm=pWC->a, j=0; j<pWC->nTerm; j++, pTerm++){
      testcase( pTerm->wtFlags & TERM_VIRTUAL );
      testcase( pTerm->wtFlags & TERM_CODED );
      if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
      if( (pTerm->prereqAll & pLevel->notReady)!=0 ){
        assert( pWInfo->untestedTerms );
        continue;
      }
      assert( pTerm->pExpr );
      sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL);
      pTerm->wtFlags |= TERM_CODED;
    }
  }

  return pLevel->notReady;
}

#ifdef WHERETRACE_ENABLED
/*
** Print the content of a WhereTerm object
*/
static void whereTermPrint(WhereTerm *pTerm, int iTerm){
  if( pTerm==0 ){
................................................................................
    int i;
    for(i=0; i<pWInfo->nLevel; i++){
      WhereLevel *pLevel = &pWInfo->a[i];
      if( pLevel->pWLoop && (pLevel->pWLoop->wsFlags & WHERE_IN_ABLE) ){
        sqlite3DbFree(db, pLevel->u.in.aInLoop);
      }
    }
    whereClauseClear(&pWInfo->sWC);
    while( pWInfo->pLoops ){
      WhereLoop *p = pWInfo->pLoops;
      pWInfo->pLoops = p->pNextLoop;
      whereLoopDelete(db, p);
    }
    sqlite3DbFree(db, pWInfo);
  }
................................................................................
  return rc;
}

#ifndef SQLITE_OMIT_VIRTUALTABLE
/*
** Add all WhereLoop objects for a table of the join identified by
** pBuilder->pNew->iTab.  That table is guaranteed to be a virtual table.





















*/
static int whereLoopAddVirtual(
  WhereLoopBuilder *pBuilder,  /* WHERE clause information */
  Bitmask mExtra


){
  WhereInfo *pWInfo;           /* WHERE analysis context */
  Parse *pParse;               /* The parsing context */
  WhereClause *pWC;            /* The WHERE clause */
  struct SrcList_item *pSrc;   /* The FROM clause term to search */
  Table *pTab;
  sqlite3 *db;
................................................................................
  int nConstraint;
  int seenIn = 0;              /* True if an IN operator is seen */
  int seenVar = 0;             /* True if a non-constant constraint is seen */
  int iPhase;                  /* 0: const w/o IN, 1: const, 2: no IN,  2: IN */
  WhereLoop *pNew;
  int rc = SQLITE_OK;


  pWInfo = pBuilder->pWInfo;
  pParse = pWInfo->pParse;
  db = pParse->db;
  pWC = pBuilder->pWC;
  pNew = pBuilder->pNew;
  pSrc = &pWInfo->pTabList->a[pNew->iTab];
  pTab = pSrc->pTab;
  assert( IsVirtual(pTab) );
  pIdxInfo = allocateIndexInfo(pParse, pWC, pSrc, pBuilder->pOrderBy);
  if( pIdxInfo==0 ) return SQLITE_NOMEM;
  pNew->prereq = 0;
  pNew->rSetup = 0;
  pNew->wsFlags = WHERE_VIRTUALTABLE;
  pNew->nLTerm = 0;
  pNew->u.vtab.needFree = 0;
  pUsage = pIdxInfo->aConstraintUsage;
................................................................................
      pTerm = &pWC->a[j];
      switch( iPhase ){
        case 0:    /* Constants without IN operator */
          pIdxCons->usable = 0;
          if( (pTerm->eOperator & WO_IN)!=0 ){
            seenIn = 1;
          }
          if( pTerm->prereqRight!=0 ){
            seenVar = 1;
          }else if( (pTerm->eOperator & WO_IN)==0 ){
            pIdxCons->usable = 1;
          }
          break;
        case 1:    /* Constants with IN operators */
          assert( seenIn );
          pIdxCons->usable = (pTerm->prereqRight==0);
          break;
        case 2:    /* Variables without IN */
          assert( seenVar );
          pIdxCons->usable = (pTerm->eOperator & WO_IN)==0;
          break;
        default:   /* Variables with IN */
          assert( seenVar && seenIn );
................................................................................
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

/*
** Add WhereLoop entries to handle OR terms.  This works for either
** btrees or virtual tables.
*/

static int whereLoopAddOr(WhereLoopBuilder *pBuilder, Bitmask mExtra){



  WhereInfo *pWInfo = pBuilder->pWInfo;
  WhereClause *pWC;
  WhereLoop *pNew;
  WhereTerm *pTerm, *pWCEnd;
  int rc = SQLITE_OK;
  int iCur;
  WhereClause tempWC;
................................................................................
          for(i=0; i<sSubBuild.pWC->nTerm; i++){
            whereTermPrint(&sSubBuild.pWC->a[i], i);
          }
        }
#endif
#ifndef SQLITE_OMIT_VIRTUALTABLE
        if( IsVirtual(pItem->pTab) ){
          rc = whereLoopAddVirtual(&sSubBuild, mExtra);
        }else
#endif
        {
          rc = whereLoopAddBtree(&sSubBuild, mExtra);
        }
        if( rc==SQLITE_OK ){
          rc = whereLoopAddOr(&sSubBuild, mExtra);
        }
        assert( rc==SQLITE_OK || sCur.n==0 );
        if( sCur.n==0 ){
          sSum.n = 0;
          break;
        }else if( once ){
          whereOrMove(&sSum, &sCur);
................................................................................
static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
  WhereInfo *pWInfo = pBuilder->pWInfo;
  Bitmask mExtra = 0;
  Bitmask mPrior = 0;
  int iTab;
  SrcList *pTabList = pWInfo->pTabList;
  struct SrcList_item *pItem;

  sqlite3 *db = pWInfo->pParse->db;
  int nTabList = pWInfo->nLevel;
  int rc = SQLITE_OK;
  u8 priorJoinType = 0;
  WhereLoop *pNew;


  /* Loop over the tables in the join, from left to right */
  pNew = pBuilder->pNew;
  whereLoopInit(pNew);
  for(iTab=0, pItem=pTabList->a; iTab<nTabList; iTab++, pItem++){

    pNew->iTab = iTab;
    pNew->maskSelf = getMask(&pWInfo->sMaskSet, pItem->iCursor);
    if( ((pItem->jointype|priorJoinType) & (JT_LEFT|JT_CROSS))!=0 ){


      mExtra = mPrior;
    }
    priorJoinType = pItem->jointype;
    if( IsVirtual(pItem->pTab) ){






      rc = whereLoopAddVirtual(pBuilder, mExtra);
    }else{
      rc = whereLoopAddBtree(pBuilder, mExtra);
    }
    if( rc==SQLITE_OK ){
      rc = whereLoopAddOr(pBuilder, mExtra);
    }
    mPrior |= pNew->maskSelf;
    if( rc || db->mallocFailed ) break;
  }

  whereLoopClear(db, pNew);
  return rc;
}

/*
** Examine a WherePath (with the addition of the extra WhereLoop of the 5th
** parameters) to see if it outputs rows in the requested ORDER BY
................................................................................
    ** loops.
    */
    for(i=0; i<nOrderBy; i++){
      if( MASKBIT(i) & obSat ) continue;
      pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
      if( pOBExpr->op!=TK_COLUMN ) continue;
      if( pOBExpr->iTable!=iCur ) continue;
      pTerm = findTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn,
                       ~ready, WO_EQ|WO_ISNULL|WO_IS, 0);
      if( pTerm==0 ) continue;
      if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){
        const char *z1, *z2;
        pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
        if( !pColl ) pColl = db->pDfltColl;
        z1 = pColl->zName;
................................................................................
    if( isOrderDistinct ){
      orderDistinctMask |= pLoop->maskSelf;
      for(i=0; i<nOrderBy; i++){
        Expr *p;
        Bitmask mTerm;
        if( MASKBIT(i) & obSat ) continue;
        p = pOrderBy->a[i].pExpr;
        mTerm = exprTableUsage(&pWInfo->sMaskSet,p);
        if( mTerm==0 && !sqlite3ExprIsConstant(p) ) continue;
        if( (mTerm&~orderDistinctMask)==0 ){
          obSat |= MASKBIT(i);
        }
      }
    }
  } /* End the loop over all WhereLoops from outer-most down to inner-most */
................................................................................
  
  pWInfo = pBuilder->pWInfo;
  if( pWInfo->wctrlFlags & WHERE_FORCE_TABLE ) return 0;
  assert( pWInfo->pTabList->nSrc>=1 );
  pItem = pWInfo->pTabList->a;
  pTab = pItem->pTab;
  if( IsVirtual(pTab) ) return 0;
  if( pItem->zIndex ) return 0;
  iCur = pItem->iCursor;
  pWC = &pWInfo->sWC;
  pLoop = pBuilder->pNew;
  pLoop->wsFlags = 0;
  pLoop->nSkip = 0;
  pTerm = findTerm(pWC, iCur, -1, 0, WO_EQ|WO_IS, 0);
  if( pTerm ){
    testcase( pTerm->eOperator & WO_IS );
    pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_IPK|WHERE_ONEROW;
    pLoop->aLTerm[0] = pTerm;
    pLoop->nLTerm = 1;
    pLoop->u.btree.nEq = 1;
    /* TUNING: Cost of a rowid lookup is 10 */
................................................................................
      assert( pLoop->aLTermSpace==pLoop->aLTerm );
      if( !IsUniqueIndex(pIdx)
       || pIdx->pPartIdxWhere!=0 
       || pIdx->nKeyCol>ArraySize(pLoop->aLTermSpace) 
      ) continue;
      opMask = pIdx->uniqNotNull ? (WO_EQ|WO_IS) : WO_EQ;
      for(j=0; j<pIdx->nKeyCol; j++){
        pTerm = findTerm(pWC, iCur, pIdx->aiColumn[j], 0, opMask, pIdx);
        if( pTerm==0 ) break;
        testcase( pTerm->eOperator & WO_IS );
        pLoop->aLTerm[j] = pTerm;
      }
      if( j!=pIdx->nKeyCol ) continue;
      pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED;
      if( pIdx->isCovering || (pItem->colUsed & ~columnsInIndex(pIdx))==0 ){
................................................................................
      pLoop->rRun = 39;  /* 39==sqlite3LogEst(15) */
      break;
    }
  }
  if( pLoop->wsFlags ){
    pLoop->nOut = (LogEst)1;
    pWInfo->a[0].pWLoop = pLoop;
    pLoop->maskSelf = getMask(&pWInfo->sMaskSet, iCur);
    pWInfo->a[0].iTabCur = iCur;
    pWInfo->nRowOut = 1;
    if( pWInfo->pOrderBy ) pWInfo->nOBSat =  pWInfo->pOrderBy->nExpr;
    if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){
      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
    }
#ifdef SQLITE_DEBUG
................................................................................
  sWLB.pNew->cId = '*';
#endif

  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.
  */
  initMaskSet(pMaskSet);
  whereClauseInit(&pWInfo->sWC, pWInfo);
  whereSplit(&pWInfo->sWC, pWhere, TK_AND);
    
  /* Special case: a WHERE clause that is constant.  Evaluate the
  ** expression and either jump over all of the code or fall thru.
  */
  for(ii=0; ii<sWLB.pWC->nTerm; ii++){
    if( nTabList==0 || sqlite3ExprIsConstantNotJoin(sWLB.pWC->a[ii].pExpr) ){
      sqlite3ExprIfFalse(pParse, sWLB.pWC->a[ii].pExpr, pWInfo->iBreak,
................................................................................
  for(ii=0; ii<pTabList->nSrc; ii++){
    createMask(pMaskSet, pTabList->a[ii].iCursor);
  }
#ifndef NDEBUG
  {
    Bitmask toTheLeft = 0;
    for(ii=0; ii<pTabList->nSrc; ii++){
      Bitmask m = getMask(pMaskSet, pTabList->a[ii].iCursor);
      assert( (m-1)==toTheLeft );
      toTheLeft |= m;
    }
  }
#endif

  /* Analyze all of the subexpressions.  Note that exprAnalyze() might
  ** add new virtual terms onto the end of the WHERE clause.  We do not
  ** want to analyze these virtual terms, so start analyzing at the end
  ** and work forward so that the added virtual terms are never processed.
  */
  exprAnalyzeAll(pTabList, &pWInfo->sWC);
  if( db->mallocFailed ){
    goto whereBeginError;
  }

  if( wctrlFlags & WHERE_WANT_DISTINCT ){
    if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){
      /* The DISTINCT marking is pointless.  Ignore it. */
      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
    }else if( pOrderBy==0 ){
      /* Try to ORDER BY the result set to make distinct processing easier */
................................................................................
      pWInfo->pOrderBy = pResultSet;
    }
  }

  /* Construct the WhereLoop objects */
  WHERETRACE(0xffff,("*** Optimizer Start ***\n"));
#if defined(WHERETRACE_ENABLED)
  /* Display all terms of the WHERE clause */
  if( sqlite3WhereTrace & 0x100 ){
    int i;
    for(i=0; i<sWLB.pWC->nTerm; i++){
      whereTermPrint(&sWLB.pWC->a[i], i);
    }
  }
#endif

  if( nTabList!=1 || whereShortCut(&sWLB)==0 ){
    rc = whereLoopAddAll(&sWLB);
    if( rc ) goto whereBeginError;
  
    /* Display all of the WhereLoop objects if wheretrace is enabled */
#ifdef WHERETRACE_ENABLED /* !=0 */
    if( sqlite3WhereTrace ){
      WhereLoop *p;
      int i;
      static char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz"
                                       "ABCDEFGHIJKLMNOPQRSTUVWYXZ";
      for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){
        p->cId = zLabel[i%sizeof(zLabel)];
        whereLoopPrint(p, sWLB.pWC);
      }
    }
#endif
  
................................................................................
  }
  if( pWInfo->pOrderBy==0 && (db->flags & SQLITE_ReverseOrder)!=0 ){
     pWInfo->revMask = (Bitmask)(-1);
  }
  if( pParse->nErr || NEVER(db->mallocFailed) ){
    goto whereBeginError;
  }
#ifdef WHERETRACE_ENABLED /* !=0 */
  if( sqlite3WhereTrace ){
    sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo->nRowOut);
    if( pWInfo->nOBSat>0 ){
      sqlite3DebugPrintf(" ORDERBY=%d,0x%llx", pWInfo->nOBSat, pWInfo->revMask);
    }
    switch( pWInfo->eDistinct ){
      case WHERE_DISTINCT_UNIQUE: {
................................................................................
  }
#endif
  /* Attempt to omit tables from the join that do not effect the result */
  if( pWInfo->nLevel>=2
   && pResultSet!=0
   && OptimizationEnabled(db, SQLITE_OmitNoopJoin)
  ){
    Bitmask tabUsed = exprListTableUsage(pMaskSet, pResultSet);

    if( sWLB.pOrderBy ) tabUsed |= exprListTableUsage(pMaskSet, sWLB.pOrderBy);

    while( pWInfo->nLevel>=2 ){
      WhereTerm *pTerm, *pEnd;
      pLoop = pWInfo->a[pWInfo->nLevel-1].pWLoop;
      if( (pWInfo->pTabList->a[pLoop->iTab].jointype & JT_LEFT)==0 ) break;
      if( (wctrlFlags & WHERE_WANT_DISTINCT)==0
       && (pLoop->wsFlags & WHERE_ONEROW)==0
      ){
................................................................................
  }
  WHERETRACE(0xffff,("*** Optimizer Finished ***\n"));
  pWInfo->pParse->nQueryLoop += pWInfo->nRowOut;

  /* If the caller is an UPDATE or DELETE statement that is requesting
  ** to use a one-pass algorithm, determine if this is appropriate.
  ** The one-pass algorithm only works if the WHERE clause constrains
  ** the statement to update a single row.
  */
  assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 
   && (pWInfo->a[0].pWLoop->wsFlags & WHERE_ONEROW)!=0 ){
    pWInfo->okOnePass = 1;
    if( HasRowid(pTabList->a[0].pTab) ){
      pWInfo->a[0].pWLoop->wsFlags &= ~WHERE_IDX_ONLY;
    }
  }

  /* Open all tables in the pTabList and any indices selected for
  ** searching those tables.
  */
  notReady = ~(Bitmask)0;
  for(ii=0, pLevel=pWInfo->a; ii<nTabList; ii++, pLevel++){
    Table *pTab;     /* Table to open */
    int iDb;         /* Index of database containing table/index */
    struct SrcList_item *pTabItem;

    pTabItem = &pTabList->a[pLevel->iFrom];
    pTab = pTabItem->pTab;
................................................................................
        Bitmask b = pTabItem->colUsed;
        int n = 0;
        for(; b; b=b>>1, n++){}
        sqlite3VdbeChangeP4(v, sqlite3VdbeCurrentAddr(v)-1, 
                            SQLITE_INT_TO_PTR(n), P4_INT32);
        assert( n<=pTab->nCol );
      }




    }else{
      sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
    }
    if( pLoop->wsFlags & WHERE_INDEXED ){
      Index *pIx = pLoop->u.btree.pIndex;
      int iIndexCur;
      int op = OP_OpenRead;
................................................................................
        if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0
         && (pLoop->wsFlags & (WHERE_COLUMN_RANGE|WHERE_SKIPSCAN))==0
         && (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0
        ){
          sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ); /* Hint to COMDB2 */
        }
        VdbeComment((v, "%s", pIx->zName));















      }
    }
    if( iDb>=0 ) sqlite3CodeVerifySchema(pParse, iDb);
    notReady &= ~getMask(&pWInfo->sMaskSet, pTabItem->iCursor);
  }
  pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
  if( db->mallocFailed ) goto whereBeginError;

  /* Generate the code to do the search.  Each iteration of the for
  ** loop below generates code for a single nested loop of the VM
  ** program.
................................................................................
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){
      constructAutomaticIndex(pParse, &pWInfo->sWC,
                &pTabList->a[pLevel->iFrom], notReady, pLevel);
      if( db->mallocFailed ) goto whereBeginError;
    }
#endif
    addrExplain = explainOneScan(
        pParse, pTabList, pLevel, ii, pLevel->iFrom, wctrlFlags
    );
    pLevel->addrBody = sqlite3VdbeCurrentAddr(v);
    notReady = codeOneLoopStart(pWInfo, ii, notReady);
    pWInfo->iContinue = pLevel->addrCont;
    if( (wsFlags&WHERE_MULTI_OR)==0 && (wctrlFlags&WHERE_ONETABLE_ONLY)==0 ){
      addScanStatus(v, pTabList, pLevel, addrExplain);
    }
  }

  /* Done. */
  VdbeModuleComment((v, "Begin WHERE-core"));
  return pWInfo;

................................................................................
    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,  /* Cx */
    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,  /* Dx */
    0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,  /* Ex */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0,  /* Fx */
};
#define IdChar(C)  (((c=C)>=0x42 && sqlite3IsEbcdicIdChar[c-0x40]))
#endif



SQLITE_PRIVATE int sqlite3IsIdChar(u8 c){ return IdChar(c); }



/*
** Return the length of the token that begins at z[0]. 
** Store the token type in *tokenType before returning.
*/
SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *z, int *tokenType){
................................................................................
#if SQLITE_TEMP_STORE==1
  return ( db->temp_store==2 );
#endif
#if SQLITE_TEMP_STORE==2
  return ( db->temp_store!=1 );
#endif
#if SQLITE_TEMP_STORE==3

  return 1;
#endif
#if SQLITE_TEMP_STORE<1 || SQLITE_TEMP_STORE>3

  return 0;
#endif
}

/*
** Return UTF-8 encoded English language explanation of the most recent
** error.
................................................................................
}

/*
** Interface to the testing logic.
*/
SQLITE_API int SQLITE_CDECL sqlite3_test_control(int op, ...){
  int rc = 0;
#ifndef SQLITE_OMIT_BUILTIN_TEST


  va_list ap;
  va_start(ap, op);
  switch( op ){

    /*
    ** Save the current state of the PRNG.
    */
................................................................................
  int prevEscape = 0;     /* True if the previous character was uEsc */

  while( zPattern[iPattern]!=0 ){

    /* Read (and consume) the next character from the input pattern. */
    UChar32 uPattern;
    U8_NEXT_UNSAFE(zPattern, iPattern, uPattern);
    assert(uPattern!=0);

    /* There are now 4 possibilities:
    **
    **     1. uPattern is an unescaped match-all character "%",
    **     2. uPattern is an unescaped match-one character "_",
    **     3. uPattern is an unescaped escape character, or
    **     4. uPattern is to be handled as an ordinary character
................................................................................
  UErrorCode status = U_ZERO_ERROR;
  const char *zLocale;      /* Locale identifier - (eg. "jp_JP") */
  const char *zName;        /* SQL Collation sequence name (eg. "japanese") */
  UCollator *pUCollator;    /* ICU library collation object */
  int rc;                   /* Return code from sqlite3_create_collation_x() */

  assert(nArg==2);

  zLocale = (const char *)sqlite3_value_text(apArg[0]);
  zName = (const char *)sqlite3_value_text(apArg[1]);

  if( !zLocale || !zName ){
    return;
  }

................................................................................
  return SQLITE_OK;
}

/*
** The set of routines that implement the simple tokenizer
*/
static const sqlite3_tokenizer_module icuTokenizerModule = {
  0,                           /* iVersion */
  icuCreate,                   /* xCreate  */
  icuDestroy,                  /* xCreate  */
  icuOpen,                     /* xOpen    */
  icuClose,                    /* xClose   */
  icuNext,                     /* xNext    */

};

/*
** Set *ppModule to point at the implementation of the ICU tokenizer.
*/
SQLITE_PRIVATE void sqlite3Fts3IcuTokenizerModule(
  sqlite3_tokenizer_module const**ppModule

** "experimental".  Experimental interfaces are normally new
** features recently added to SQLite.  We do not anticipate changes
** to experimental interfaces but reserve the right to make minor changes
** if experience from use "in the wild" suggest such changes are prudent.
**
** The official C-language API documentation for SQLite is derived
** from comments in this file.  This file is the authoritative source
** on how SQLite interfaces are supposed to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
*/
#ifndef _SQLITE3_H_
................................................................................
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.8.11"
#define SQLITE_VERSION_NUMBER 3008011
#define SQLITE_SOURCE_ID      "2015-06-26 02:41:31 015302f15e46a087ec92f3644c6741600dbf4306"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
#define OP_OpenWrite      55 /* synopsis: root=P2 iDb=P3                   */
#define OP_OpenAutoindex  56 /* synopsis: nColumn=P2                       */
#define OP_OpenEphemeral  57 /* synopsis: nColumn=P2                       */
#define OP_SorterOpen     58
#define OP_SequenceTest   59 /* synopsis: if( cursor[P1].ctr++ ) pc = P2   */
#define OP_OpenPseudo     60 /* synopsis: P3 columns in r[P2]              */
#define OP_Close          61
#define OP_ColumnsUsed    62
#define OP_SeekLT         63 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekLE         64 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekGE         65 /* synopsis: key=r[P3@P4]                     */
#define OP_SeekGT         66 /* synopsis: key=r[P3@P4]                     */
#define OP_Seek           67 /* synopsis: intkey=r[P2]                     */
#define OP_NoConflict     68 /* synopsis: key=r[P3@P4]                     */
#define OP_NotFound       69 /* synopsis: key=r[P3@P4]                     */
#define OP_Found          70 /* synopsis: key=r[P3@P4]                     */

#define OP_Or             71 /* same as TK_OR, synopsis: r[P3]=(r[P1] || r[P2]) */
#define OP_And            72 /* same as TK_AND, synopsis: r[P3]=(r[P1] && r[P2]) */
#define OP_NotExists      73 /* synopsis: intkey=r[P3]                     */
#define OP_Sequence       74 /* synopsis: r[P2]=cursor[P1].ctr++           */
#define OP_NewRowid       75 /* synopsis: r[P2]=rowid                      */

#define OP_IsNull         76 /* same as TK_ISNULL, synopsis: if r[P1]==NULL goto P2 */
#define OP_NotNull        77 /* same as TK_NOTNULL, synopsis: if r[P1]!=NULL goto P2 */
#define OP_Ne             78 /* same as TK_NE, synopsis: if r[P1]!=r[P3] goto P2 */
#define OP_Eq             79 /* same as TK_EQ, synopsis: if r[P1]==r[P3] goto P2 */
#define OP_Gt             80 /* same as TK_GT, synopsis: if r[P1]>r[P3] goto P2 */
#define OP_Le             81 /* same as TK_LE, synopsis: if r[P1]<=r[P3] goto P2 */
#define OP_Lt             82 /* same as TK_LT, synopsis: if r[P1]<r[P3] goto P2 */
#define OP_Ge             83 /* same as TK_GE, synopsis: if r[P1]>=r[P3] goto P2 */
#define OP_Insert         84 /* synopsis: intkey=r[P3] data=r[P2]          */
#define OP_BitAnd         85 /* same as TK_BITAND, synopsis: r[P3]=r[P1]&r[P2] */
#define OP_BitOr          86 /* same as TK_BITOR, synopsis: r[P3]=r[P1]|r[P2] */
#define OP_ShiftLeft      87 /* same as TK_LSHIFT, synopsis: r[P3]=r[P2]<<r[P1] */
#define OP_ShiftRight     88 /* same as TK_RSHIFT, synopsis: r[P3]=r[P2]>>r[P1] */
#define OP_Add            89 /* same as TK_PLUS, synopsis: r[P3]=r[P1]+r[P2] */
#define OP_Subtract       90 /* same as TK_MINUS, synopsis: r[P3]=r[P2]-r[P1] */
#define OP_Multiply       91 /* same as TK_STAR, synopsis: r[P3]=r[P1]*r[P2] */
#define OP_Divide         92 /* same as TK_SLASH, synopsis: r[P3]=r[P2]/r[P1] */
#define OP_Remainder      93 /* same as TK_REM, synopsis: r[P3]=r[P2]%r[P1] */
#define OP_Concat         94 /* same as TK_CONCAT, synopsis: r[P3]=r[P2]+r[P1] */
#define OP_InsertInt      95 /* synopsis: intkey=P3 data=r[P2]             */
#define OP_BitNot         96 /* same as TK_BITNOT, synopsis: r[P1]= ~r[P1] */
#define OP_String8        97 /* same as TK_STRING, synopsis: r[P2]='P4'    */
#define OP_Delete         98
#define OP_ResetCount     99
#define OP_SorterCompare 100 /* synopsis: if key(P1)!=trim(r[P3],P4) goto P2 */
#define OP_SorterData    101 /* synopsis: r[P2]=data                       */
#define OP_RowKey        102 /* synopsis: r[P2]=key                        */
#define OP_RowData       103 /* synopsis: r[P2]=data                       */
#define OP_Rowid         104 /* synopsis: r[P2]=rowid                      */
#define OP_NullRow       105
#define OP_Last          106
#define OP_SorterSort    107
#define OP_Sort          108
#define OP_Rewind        109
#define OP_SorterInsert  110
#define OP_IdxInsert     111 /* synopsis: key=r[P2]                        */
#define OP_IdxDelete     112 /* synopsis: key=r[P2@P3]                     */
#define OP_IdxRowid      113 /* synopsis: r[P2]=rowid                      */
#define OP_IdxLE         114 /* synopsis: key=r[P3@P4]                     */
#define OP_IdxGT         115 /* synopsis: key=r[P3@P4]                     */
#define OP_IdxLT         116 /* synopsis: key=r[P3@P4]                     */
#define OP_IdxGE         117 /* synopsis: key=r[P3@P4]                     */
#define OP_Destroy       118
#define OP_Clear         119
#define OP_ResetSorter   120
#define OP_CreateIndex   121 /* synopsis: r[P2]=root iDb=P1                */
#define OP_CreateTable   122 /* synopsis: r[P2]=root iDb=P1                */
#define OP_ParseSchema   123
#define OP_LoadAnalysis  124
#define OP_DropTable     125
#define OP_DropIndex     126
#define OP_DropTrigger   127
#define OP_IntegrityCk   128
#define OP_RowSetAdd     129 /* synopsis: rowset(P1)=r[P2]                 */
#define OP_RowSetRead    130 /* synopsis: r[P3]=rowset(P1)                 */
#define OP_RowSetTest    131 /* synopsis: if r[P3] in rowset(P1) goto P2   */
#define OP_Program       132

#define OP_Real          133 /* same as TK_FLOAT, synopsis: r[P2]=P4       */
#define OP_Param         134
#define OP_FkCounter     135 /* synopsis: fkctr[P1]+=P2                    */
#define OP_FkIfZero      136 /* synopsis: if fkctr[P1]==0 goto P2          */
#define OP_MemMax        137 /* synopsis: r[P1]=max(r[P1],r[P2])           */
#define OP_IfPos         138 /* synopsis: if r[P1]>0 goto P2               */
#define OP_IfNeg         139 /* synopsis: r[P1]+=P3, if r[P1]<0 goto P2    */
#define OP_IfNotZero     140 /* synopsis: if r[P1]!=0 then r[P1]+=P3, goto P2 */
#define OP_DecrJumpZero  141 /* synopsis: if (--r[P1])==0 goto P2          */
#define OP_JumpZeroIncr  142 /* synopsis: if (r[P1]++)==0 ) goto P2        */
#define OP_AggFinal      143 /* synopsis: accum=r[P1] N=P2                 */
#define OP_IncrVacuum    144
#define OP_Expire        145
#define OP_TableLock     146 /* synopsis: iDb=P1 root=P2 write=P3          */
#define OP_VBegin        147
#define OP_VCreate       148
#define OP_VDestroy      149
#define OP_VOpen         150
#define OP_VColumn       151 /* synopsis: r[P3]=vcolumn(P2)                */
#define OP_VNext         152
#define OP_VRename       153
#define OP_Pagecount     154
#define OP_MaxPgcnt      155
#define OP_Init          156 /* synopsis: Start at P2                      */
#define OP_Noop          157
#define OP_Explain       158


/* Properties such as "out2" or "jump" that are specified in
** comments following the "case" for each opcode in the vdbe.c
** are encoded into bitvectors as follows:
*/
#define OPFLG_JUMP            0x0001  /* jump:  P2 holds jmp target */
................................................................................
/*   0 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01,\
/*   8 */ 0x01, 0x01, 0x00, 0x00, 0x10, 0x00, 0x01, 0x00,\
/*  16 */ 0x01, 0x01, 0x02, 0x12, 0x01, 0x02, 0x03, 0x08,\
/*  24 */ 0x00, 0x10, 0x10, 0x10, 0x10, 0x00, 0x10, 0x10,\
/*  32 */ 0x00, 0x00, 0x10, 0x00, 0x00, 0x02, 0x03, 0x02,\
/*  40 */ 0x02, 0x00, 0x00, 0x01, 0x01, 0x03, 0x03, 0x00,\
/*  48 */ 0x00, 0x00, 0x10, 0x10, 0x08, 0x00, 0x00, 0x00,\
/*  56 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x09,\
/*  64 */ 0x09, 0x09, 0x09, 0x04, 0x09, 0x09, 0x09, 0x26,\
/*  72 */ 0x26, 0x09, 0x10, 0x10, 0x03, 0x03, 0x0b, 0x0b,\
/*  80 */ 0x0b, 0x0b, 0x0b, 0x0b, 0x00, 0x26, 0x26, 0x26,\
/*  88 */ 0x26, 0x26, 0x26, 0x26, 0x26, 0x26, 0x26, 0x00,\
/*  96 */ 0x12, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
/* 104 */ 0x10, 0x00, 0x01, 0x01, 0x01, 0x01, 0x04, 0x04,\
/* 112 */ 0x00, 0x10, 0x01, 0x01, 0x01, 0x01, 0x10, 0x00,\
/* 120 */ 0x00, 0x10, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00,\
/* 128 */ 0x00, 0x06, 0x23, 0x0b, 0x01, 0x10, 0x10, 0x00,\
/* 136 */ 0x01, 0x04, 0x03, 0x03, 0x03, 0x03, 0x03, 0x00,\
/* 144 */ 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
/* 152 */ 0x01, 0x00, 0x10, 0x10, 0x01, 0x00, 0x00,}

/************** End of opcodes.h *********************************************/
/************** Continuing where we left off in vdbe.h ***********************/

/*
** Prototypes for the VDBE interface.  See comments on the implementation
** for a description of what each of these routines does.
................................................................................
*/
SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(Parse*);
SQLITE_PRIVATE int sqlite3VdbeAddOp0(Vdbe*,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp1(Vdbe*,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp2(Vdbe*,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp3(Vdbe*,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4(Vdbe*,int,int,int,int,const char *zP4,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4Dup8(Vdbe*,int,int,int,int,const u8*,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(Vdbe*,int,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp, int iLineno);
SQLITE_PRIVATE void sqlite3VdbeAddParseSchemaOp(Vdbe*,int,char*);
SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe*, u32 addr, int P1);
SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe*, u32 addr, int P2);
SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe*, u32 addr, int P3);
SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe*, u8 P5);
................................................................................
** the speed a little by numbering the values consecutively.  
**
** But rather than start with 0 or 1, we begin with 'A'.  That way,
** when multiple affinity types are concatenated into a string and
** used as the P4 operand, they will be more readable.
**
** Note also that the numeric types are grouped together so that testing
** for a numeric type is a single comparison.  And the BLOB type is first.
*/
#define SQLITE_AFF_BLOB     'A'
#define SQLITE_AFF_TEXT     'B'
#define SQLITE_AFF_NUMERIC  'C'
#define SQLITE_AFF_INTEGER  'D'
#define SQLITE_AFF_REAL     'E'

#define sqlite3IsNumericAffinity(X)  ((X)>=SQLITE_AFF_NUMERIC)

................................................................................
#ifndef SQLITE_OMIT_EXPLAIN
    u8 iSelectId;     /* If pSelect!=0, the id of the sub-select in EQP */
#endif
    int iCursor;      /* The VDBE cursor number used to access this table */
    Expr *pOn;        /* The ON clause of a join */
    IdList *pUsing;   /* The USING clause of a join */
    Bitmask colUsed;  /* Bit N (1<<N) set if column N of pTab is used */
    char *zIndexedBy; /* Identifier from "INDEXED BY <zIndex>" clause */
    Index *pIndex;    /* Index structure corresponding to zIndex, if any */
  } a[1];             /* One entry for each identifier on the list */
};

/*
** Permitted values of the SrcList.a.jointype field
*/
................................................................................
# define sqlite3Isspace(x)   isspace((unsigned char)(x))
# define sqlite3Isalnum(x)   isalnum((unsigned char)(x))
# define sqlite3Isalpha(x)   isalpha((unsigned char)(x))
# define sqlite3Isdigit(x)   isdigit((unsigned char)(x))
# define sqlite3Isxdigit(x)  isxdigit((unsigned char)(x))
# define sqlite3Tolower(x)   tolower((unsigned char)(x))
#endif
#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
SQLITE_PRIVATE int sqlite3IsIdChar(u8);
#endif

/*
** Internal function prototypes
*/
#define sqlite3StrICmp sqlite3_stricmp
SQLITE_PRIVATE int sqlite3Strlen30(const char*);
#define sqlite3StrNICmp sqlite3_strnicmp
................................................................................
SQLITE_PRIVATE int sqlite3MallocSize(void*);
SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3*, void*);
SQLITE_PRIVATE void *sqlite3ScratchMalloc(int);
SQLITE_PRIVATE void sqlite3ScratchFree(void*);
SQLITE_PRIVATE void *sqlite3PageMalloc(int);
SQLITE_PRIVATE void sqlite3PageFree(void*);
SQLITE_PRIVATE void sqlite3MemSetDefault(void);
#ifndef SQLITE_OMIT_BUILTIN_TEST
SQLITE_PRIVATE void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
#endif
SQLITE_PRIVATE int sqlite3HeapNearlyFull(void);

/*
** On systems with ample stack space and that support alloca(), make
** use of alloca() to obtain space for large automatic objects.  By default,
** obtain space from malloc().
**
................................................................................
SQLITE_PRIVATE   void sqlite3DebugPrintf(const char*, ...);
#endif
#if defined(SQLITE_TEST)
SQLITE_PRIVATE   void *sqlite3TestTextToPtr(const char*);
#endif

#if defined(SQLITE_DEBUG)




SQLITE_PRIVATE   void sqlite3TreeViewExpr(TreeView*, const Expr*, u8);
SQLITE_PRIVATE   void sqlite3TreeViewExprList(TreeView*, const ExprList*, u8, const char*);
SQLITE_PRIVATE   void sqlite3TreeViewSelect(TreeView*, const Select*, u8);
#endif


SQLITE_PRIVATE void sqlite3SetString(char **, sqlite3*, const char*);
................................................................................

SQLITE_PRIVATE Bitvec *sqlite3BitvecCreate(u32);
SQLITE_PRIVATE int sqlite3BitvecTest(Bitvec*, u32);
SQLITE_PRIVATE int sqlite3BitvecSet(Bitvec*, u32);
SQLITE_PRIVATE void sqlite3BitvecClear(Bitvec*, u32, void*);
SQLITE_PRIVATE void sqlite3BitvecDestroy(Bitvec*);
SQLITE_PRIVATE u32 sqlite3BitvecSize(Bitvec*);
#ifndef SQLITE_OMIT_BUILTIN_TEST
SQLITE_PRIVATE int sqlite3BitvecBuiltinTest(int,int*);
#endif

SQLITE_PRIVATE RowSet *sqlite3RowSetInit(sqlite3*, void*, unsigned int);
SQLITE_PRIVATE void sqlite3RowSetClear(RowSet*);
SQLITE_PRIVATE void sqlite3RowSetInsert(RowSet*, i64);
SQLITE_PRIVATE int sqlite3RowSetTest(RowSet*, int iBatch, i64);
SQLITE_PRIVATE int sqlite3RowSetNext(RowSet*, i64*);

................................................................................
SQLITE_PRIVATE int sqlite3ExprCodeTarget(Parse*, Expr*, int);
SQLITE_PRIVATE void sqlite3ExprCodeAndCache(Parse*, Expr*, int);
SQLITE_PRIVATE int sqlite3ExprCodeExprList(Parse*, ExprList*, int, u8);
#define SQLITE_ECEL_DUP      0x01  /* Deep, not shallow copies */
#define SQLITE_ECEL_FACTOR   0x02  /* Factor out constant terms */
SQLITE_PRIVATE void sqlite3ExprIfTrue(Parse*, Expr*, int, int);
SQLITE_PRIVATE void sqlite3ExprIfFalse(Parse*, Expr*, int, int);
SQLITE_PRIVATE void sqlite3ExprIfFalseDup(Parse*, Expr*, int, int);
SQLITE_PRIVATE Table *sqlite3FindTable(sqlite3*,const char*, const char*);
SQLITE_PRIVATE Table *sqlite3LocateTable(Parse*,int isView,const char*, const char*);
SQLITE_PRIVATE Table *sqlite3LocateTableItem(Parse*,int isView,struct SrcList_item *);
SQLITE_PRIVATE Index *sqlite3FindIndex(sqlite3*,const char*, const char*);
SQLITE_PRIVATE void sqlite3UnlinkAndDeleteTable(sqlite3*,int,const char*);
SQLITE_PRIVATE void sqlite3UnlinkAndDeleteIndex(sqlite3*,int,const char*);
SQLITE_PRIVATE void sqlite3Vacuum(Parse*);
................................................................................
SQLITE_PRIVATE int sqlite3ExprCompare(Expr*, Expr*, int);
SQLITE_PRIVATE int sqlite3ExprListCompare(ExprList*, ExprList*, int);
SQLITE_PRIVATE int sqlite3ExprImpliesExpr(Expr*, Expr*, int);
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
SQLITE_PRIVATE int sqlite3FunctionUsesThisSrc(Expr*, SrcList*);
SQLITE_PRIVATE Vdbe *sqlite3GetVdbe(Parse*);
#ifndef SQLITE_OMIT_BUILTIN_TEST
SQLITE_PRIVATE void sqlite3PrngSaveState(void);
SQLITE_PRIVATE void sqlite3PrngRestoreState(void);
#endif
SQLITE_PRIVATE void sqlite3RollbackAll(sqlite3*,int);
SQLITE_PRIVATE void sqlite3CodeVerifySchema(Parse*, int);
SQLITE_PRIVATE void sqlite3CodeVerifyNamedSchema(Parse*, const char *zDb);
SQLITE_PRIVATE void sqlite3BeginTransaction(Parse*, int);
SQLITE_PRIVATE void sqlite3CommitTransaction(Parse*);
SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse*);
SQLITE_PRIVATE void sqlite3Savepoint(Parse*, int, Token*);
................................................................................
SQLITE_PRIVATE void sqlite3AlterFunctions(void);
SQLITE_PRIVATE void sqlite3AlterRenameTable(Parse*, SrcList*, Token*);
SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *, int *);
SQLITE_PRIVATE void sqlite3NestedParse(Parse*, const char*, ...);
SQLITE_PRIVATE void sqlite3ExpirePreparedStatements(sqlite3*);
SQLITE_PRIVATE int sqlite3CodeSubselect(Parse *, Expr *, int, int);
SQLITE_PRIVATE void sqlite3SelectPrep(Parse*, Select*, NameContext*);
SQLITE_PRIVATE void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p);
SQLITE_PRIVATE int sqlite3MatchSpanName(const char*, const char*, const char*, const char*);
SQLITE_PRIVATE int sqlite3ResolveExprNames(NameContext*, Expr*);
SQLITE_PRIVATE void sqlite3ResolveSelectNames(Parse*, Select*, NameContext*);
SQLITE_PRIVATE void sqlite3ResolveSelfReference(Parse*,Table*,int,Expr*,ExprList*);
SQLITE_PRIVATE int sqlite3ResolveOrderGroupBy(Parse*, Select*, ExprList*, const char*);
SQLITE_PRIVATE void sqlite3ColumnDefault(Vdbe *, Table *, int, int);
SQLITE_PRIVATE void sqlite3AlterFinishAddColumn(Parse *, Token *);
................................................................................
  Bool isTable:1;       /* True if a table requiring integer keys */
  Bool isOrdered:1;     /* True if the underlying table is BTREE_UNORDERED */
  Pgno pgnoRoot;        /* Root page of the open btree cursor */
  sqlite3_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
  i64 seqCount;         /* Sequence counter */
  i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
  VdbeSorter *pSorter;  /* Sorter object for OP_SorterOpen cursors */
#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
  u64 maskUsed;         /* Mask of columns used by this cursor */
#endif

  /* Cached information about the header for the data record that the
  ** cursor is currently pointing to.  Only valid if cacheStatus matches
  ** Vdbe.cacheCtr.  Vdbe.cacheCtr will never take on the value of
  ** CACHE_STALE and so setting cacheStatus=CACHE_STALE guarantees that
  ** the cache is out of date.
  **
................................................................................
    sqlite3_mutex_methods *pTo = &sqlite3GlobalConfig.mutex;

    if( sqlite3GlobalConfig.bCoreMutex ){
      pFrom = sqlite3DefaultMutex();
    }else{
      pFrom = sqlite3NoopMutex();
    }
    pTo->xMutexInit = pFrom->xMutexInit;
    pTo->xMutexEnd = pFrom->xMutexEnd;
    pTo->xMutexFree = pFrom->xMutexFree;
    pTo->xMutexEnter = pFrom->xMutexEnter;
    pTo->xMutexTry = pFrom->xMutexTry;
    pTo->xMutexLeave = pFrom->xMutexLeave;
    pTo->xMutexHeld = pFrom->xMutexHeld;
    pTo->xMutexNotheld = pFrom->xMutexNotheld;
    pTo->xMutexAlloc = pFrom->xMutexAlloc;
  }
  rc = sqlite3GlobalConfig.mutex.xMutexInit();

#ifdef SQLITE_DEBUG
  GLOBAL(int, mutexIsInit) = 1;
#endif
................................................................................
  return rc & db->errMask;
}

/************** End of malloc.c **********************************************/
/************** Begin file printf.c ******************************************/
/*
** The "printf" code that follows dates from the 1980's.  It is in
** the public domain. 



**
**************************************************************************
**
** This file contains code for a set of "printf"-like routines.  These
** routines format strings much like the printf() from the standard C
** library, though the implementation here has enhancements to support
** SQLite.
*/

/*
** Conversion types fall into various categories as defined by the
** following enumeration.
*/
#define etRADIX       1 /* Integer types.  %d, %x, %o, and so forth */
................................................................................
  va_end(ap);
  sqlite3StrAccumFinish(&acc);
  fprintf(stdout,"%s", zBuf);
  fflush(stdout);
}
#endif



/*
** variable-argument wrapper around sqlite3VXPrintf().
*/
SQLITE_PRIVATE void sqlite3XPrintf(StrAccum *p, u32 bFlags, const char *zFormat, ...){
  va_list ap;
  va_start(ap,zFormat);
  sqlite3VXPrintf(p, bFlags, zFormat, ap);
  va_end(ap);
}

/************** End of printf.c **********************************************/
/************** Begin file treeview.c ****************************************/
/*
** 2015-06-08
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************


**






** This file contains C code to implement the TreeView debugging routines.
** These routines print a parse tree to standard output for debugging and
** analysis. 
**
** The interfaces in this file is only available when compiling
** with SQLITE_DEBUG.
*/
#ifdef SQLITE_DEBUG

/*
** Add a new subitem to the tree.  The moreToFollow flag indicates that this
** is not the last item in the tree.
*/
static TreeView *sqlite3TreeViewPush(TreeView *p, u8 moreToFollow){
  if( p==0 ){
    p = sqlite3_malloc64( sizeof(*p) );
    if( p==0 ) return 0;
    memset(p, 0, sizeof(*p));
  }else{
    p->iLevel++;
  }
  assert( moreToFollow==0 || moreToFollow==1 );
  if( p->iLevel<sizeof(p->bLine) ) p->bLine[p->iLevel] = moreToFollow;
  return p;
}

/*
** Finished with one layer of the tree
*/
static void sqlite3TreeViewPop(TreeView *p){
  if( p==0 ) return;
  p->iLevel--;
  if( p->iLevel<0 ) sqlite3_free(p);
}

/*
** Generate a single line of output for the tree, with a prefix that contains
** all the appropriate tree lines
*/
static void sqlite3TreeViewLine(TreeView *p, const char *zFormat, ...){
  va_list ap;
  int i;
  StrAccum acc;
  char zBuf[500];
  sqlite3StrAccumInit(&acc, 0, zBuf, sizeof(zBuf), 0);
  if( p ){
    for(i=0; i<p->iLevel && i<sizeof(p->bLine)-1; i++){
................................................................................
  sqlite3VXPrintf(&acc, 0, zFormat, ap);
  va_end(ap);
  if( zBuf[acc.nChar-1]!='\n' ) sqlite3StrAccumAppend(&acc, "\n", 1);
  sqlite3StrAccumFinish(&acc);
  fprintf(stdout,"%s", zBuf);
  fflush(stdout);
}

/*
** Shorthand for starting a new tree item that consists of a single label
*/
static void sqlite3TreeViewItem(TreeView *p, const char *zLabel,u8 moreFollows){
  p = sqlite3TreeViewPush(p, moreFollows);
  sqlite3TreeViewLine(p, "%s", zLabel);
}


/*
** Generate a human-readable description of a the Select object.
*/
SQLITE_PRIVATE void sqlite3TreeViewSelect(TreeView *pView, const Select *p, u8 moreToFollow){
  int n = 0;
  pView = sqlite3TreeViewPush(pView, moreToFollow);
  sqlite3TreeViewLine(pView, "SELECT%s%s (0x%p) selFlags=0x%x",
    ((p->selFlags & SF_Distinct) ? " DISTINCT" : ""),
    ((p->selFlags & SF_Aggregate) ? " agg_flag" : ""), p, p->selFlags
  );
  if( p->pSrc && p->pSrc->nSrc ) n++;
  if( p->pWhere ) n++;
  if( p->pGroupBy ) n++;
  if( p->pHaving ) n++;
  if( p->pOrderBy ) n++;
  if( p->pLimit ) n++;
  if( p->pOffset ) n++;
  if( p->pPrior ) n++;
  sqlite3TreeViewExprList(pView, p->pEList, (n--)>0, "result-set");
  if( p->pSrc && p->pSrc->nSrc ){
    int i;
    pView = sqlite3TreeViewPush(pView, (n--)>0);
    sqlite3TreeViewLine(pView, "FROM");
    for(i=0; i<p->pSrc->nSrc; i++){
      struct SrcList_item *pItem = &p->pSrc->a[i];
      StrAccum x;
      char zLine[100];
      sqlite3StrAccumInit(&x, 0, zLine, sizeof(zLine), 0);
      sqlite3XPrintf(&x, 0, "{%d,*}", pItem->iCursor);
      if( pItem->zDatabase ){
        sqlite3XPrintf(&x, 0, " %s.%s", pItem->zDatabase, pItem->zName);
      }else if( pItem->zName ){
        sqlite3XPrintf(&x, 0, " %s", pItem->zName);
      }
      if( pItem->pTab ){
        sqlite3XPrintf(&x, 0, " tabname=%Q", pItem->pTab->zName);
      }
      if( pItem->zAlias ){
        sqlite3XPrintf(&x, 0, " (AS %s)", pItem->zAlias);
      }
      if( pItem->jointype & JT_LEFT ){
        sqlite3XPrintf(&x, 0, " LEFT-JOIN");
      }
      sqlite3StrAccumFinish(&x);
      sqlite3TreeViewItem(pView, zLine, i<p->pSrc->nSrc-1); 
      if( pItem->pSelect ){
        sqlite3TreeViewSelect(pView, pItem->pSelect, 0);
      }
      sqlite3TreeViewPop(pView);
    }
    sqlite3TreeViewPop(pView);
  }
  if( p->pWhere ){
    sqlite3TreeViewItem(pView, "WHERE", (n--)>0);
    sqlite3TreeViewExpr(pView, p->pWhere, 0);
    sqlite3TreeViewPop(pView);
  }
  if( p->pGroupBy ){
    sqlite3TreeViewExprList(pView, p->pGroupBy, (n--)>0, "GROUPBY");
  }
  if( p->pHaving ){
    sqlite3TreeViewItem(pView, "HAVING", (n--)>0);
    sqlite3TreeViewExpr(pView, p->pHaving, 0);
    sqlite3TreeViewPop(pView);
  }
  if( p->pOrderBy ){
    sqlite3TreeViewExprList(pView, p->pOrderBy, (n--)>0, "ORDERBY");
  }
  if( p->pLimit ){
    sqlite3TreeViewItem(pView, "LIMIT", (n--)>0);
    sqlite3TreeViewExpr(pView, p->pLimit, 0);
    sqlite3TreeViewPop(pView);
  }
  if( p->pOffset ){
    sqlite3TreeViewItem(pView, "OFFSET", (n--)>0);
    sqlite3TreeViewExpr(pView, p->pOffset, 0);
    sqlite3TreeViewPop(pView);
  }
  if( p->pPrior ){
    const char *zOp = "UNION";
    switch( p->op ){
      case TK_ALL:         zOp = "UNION ALL";  break;
      case TK_INTERSECT:   zOp = "INTERSECT";  break;
      case TK_EXCEPT:      zOp = "EXCEPT";     break;
    }
    sqlite3TreeViewItem(pView, zOp, (n--)>0);
    sqlite3TreeViewSelect(pView, p->pPrior, 0);
    sqlite3TreeViewPop(pView);
  }
  sqlite3TreeViewPop(pView);
}

/*
** Generate a human-readable explanation of an expression tree.
*/
SQLITE_PRIVATE void sqlite3TreeViewExpr(TreeView *pView, const Expr *pExpr, u8 moreToFollow){
  const char *zBinOp = 0;   /* Binary operator */
  const char *zUniOp = 0;   /* Unary operator */
  char zFlgs[30];
  pView = sqlite3TreeViewPush(pView, moreToFollow);
  if( pExpr==0 ){
    sqlite3TreeViewLine(pView, "nil");
    sqlite3TreeViewPop(pView);
    return;
  }
  if( pExpr->flags ){
    sqlite3_snprintf(sizeof(zFlgs),zFlgs,"  flags=0x%x",pExpr->flags);
  }else{
    zFlgs[0] = 0;
  }
  switch( pExpr->op ){
    case TK_AGG_COLUMN: {
      sqlite3TreeViewLine(pView, "AGG{%d:%d}%s",
            pExpr->iTable, pExpr->iColumn, zFlgs);
      break;
    }
    case TK_COLUMN: {
      if( pExpr->iTable<0 ){
        /* This only happens when coding check constraints */
        sqlite3TreeViewLine(pView, "COLUMN(%d)%s", pExpr->iColumn, zFlgs);
      }else{
        sqlite3TreeViewLine(pView, "{%d:%d}%s",
                             pExpr->iTable, pExpr->iColumn, zFlgs);
      }
      break;
    }
    case TK_INTEGER: {
      if( pExpr->flags & EP_IntValue ){
        sqlite3TreeViewLine(pView, "%d", pExpr->u.iValue);
      }else{
        sqlite3TreeViewLine(pView, "%s", pExpr->u.zToken);
      }
      break;
    }
#ifndef SQLITE_OMIT_FLOATING_POINT
    case TK_FLOAT: {
      sqlite3TreeViewLine(pView,"%s", pExpr->u.zToken);
      break;
    }
#endif
    case TK_STRING: {
      sqlite3TreeViewLine(pView,"%Q", pExpr->u.zToken);
      break;
    }
    case TK_NULL: {
      sqlite3TreeViewLine(pView,"NULL");
      break;
    }
#ifndef SQLITE_OMIT_BLOB_LITERAL
    case TK_BLOB: {
      sqlite3TreeViewLine(pView,"%s", pExpr->u.zToken);
      break;
    }
#endif
    case TK_VARIABLE: {
      sqlite3TreeViewLine(pView,"VARIABLE(%s,%d)",
                          pExpr->u.zToken, pExpr->iColumn);
      break;
    }
    case TK_REGISTER: {
      sqlite3TreeViewLine(pView,"REGISTER(%d)", pExpr->iTable);
      break;
    }
    case TK_AS: {
      sqlite3TreeViewLine(pView,"AS %Q", pExpr->u.zToken);
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
      break;
    }
    case TK_ID: {
      sqlite3TreeViewLine(pView,"ID \"%w\"", pExpr->u.zToken);
      break;
    }
#ifndef SQLITE_OMIT_CAST
    case TK_CAST: {
      /* Expressions of the form:   CAST(pLeft AS token) */
      sqlite3TreeViewLine(pView,"CAST %Q", pExpr->u.zToken);
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
      break;
    }
#endif /* SQLITE_OMIT_CAST */
    case TK_LT:      zBinOp = "LT";     break;
    case TK_LE:      zBinOp = "LE";     break;
    case TK_GT:      zBinOp = "GT";     break;
    case TK_GE:      zBinOp = "GE";     break;
    case TK_NE:      zBinOp = "NE";     break;
    case TK_EQ:      zBinOp = "EQ";     break;
    case TK_IS:      zBinOp = "IS";     break;
    case TK_ISNOT:   zBinOp = "ISNOT";  break;
    case TK_AND:     zBinOp = "AND";    break;
    case TK_OR:      zBinOp = "OR";     break;
    case TK_PLUS:    zBinOp = "ADD";    break;
    case TK_STAR:    zBinOp = "MUL";    break;
    case TK_MINUS:   zBinOp = "SUB";    break;
    case TK_REM:     zBinOp = "REM";    break;
    case TK_BITAND:  zBinOp = "BITAND"; break;
    case TK_BITOR:   zBinOp = "BITOR";  break;
    case TK_SLASH:   zBinOp = "DIV";    break;
    case TK_LSHIFT:  zBinOp = "LSHIFT"; break;
    case TK_RSHIFT:  zBinOp = "RSHIFT"; break;
    case TK_CONCAT:  zBinOp = "CONCAT"; break;
    case TK_DOT:     zBinOp = "DOT";    break;

    case TK_UMINUS:  zUniOp = "UMINUS"; break;
    case TK_UPLUS:   zUniOp = "UPLUS";  break;
    case TK_BITNOT:  zUniOp = "BITNOT"; break;
    case TK_NOT:     zUniOp = "NOT";    break;
    case TK_ISNULL:  zUniOp = "ISNULL"; break;
    case TK_NOTNULL: zUniOp = "NOTNULL"; break;

    case TK_COLLATE: {
      sqlite3TreeViewLine(pView, "COLLATE %Q", pExpr->u.zToken);
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
      break;
    }

    case TK_AGG_FUNCTION:
    case TK_FUNCTION: {
      ExprList *pFarg;       /* List of function arguments */
      if( ExprHasProperty(pExpr, EP_TokenOnly) ){
        pFarg = 0;
      }else{
        pFarg = pExpr->x.pList;
      }
      if( pExpr->op==TK_AGG_FUNCTION ){
        sqlite3TreeViewLine(pView, "AGG_FUNCTION%d %Q",
                             pExpr->op2, pExpr->u.zToken);
      }else{
        sqlite3TreeViewLine(pView, "FUNCTION %Q", pExpr->u.zToken);
      }
      if( pFarg ){
        sqlite3TreeViewExprList(pView, pFarg, 0, 0);
      }
      break;
    }
#ifndef SQLITE_OMIT_SUBQUERY
    case TK_EXISTS: {
      sqlite3TreeViewLine(pView, "EXISTS-expr");
      sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
      break;
    }
    case TK_SELECT: {
      sqlite3TreeViewLine(pView, "SELECT-expr");
      sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
      break;
    }
    case TK_IN: {
      sqlite3TreeViewLine(pView, "IN");
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
        sqlite3TreeViewSelect(pView, pExpr->x.pSelect, 0);
      }else{
        sqlite3TreeViewExprList(pView, pExpr->x.pList, 0, 0);
      }
      break;
    }
#endif /* SQLITE_OMIT_SUBQUERY */

    /*

    **    x BETWEEN y AND z
    **
    ** This is equivalent to
    **
    **    x>=y AND x<=z
    **
    ** X is stored in pExpr->pLeft.
    ** Y is stored in pExpr->pList->a[0].pExpr.
    ** Z is stored in pExpr->pList->a[1].pExpr.
    */
    case TK_BETWEEN: {
      Expr *pX = pExpr->pLeft;
      Expr *pY = pExpr->x.pList->a[0].pExpr;
      Expr *pZ = pExpr->x.pList->a[1].pExpr;
      sqlite3TreeViewLine(pView, "BETWEEN");
      sqlite3TreeViewExpr(pView, pX, 1);
      sqlite3TreeViewExpr(pView, pY, 1);
      sqlite3TreeViewExpr(pView, pZ, 0);
      break;
    }
    case TK_TRIGGER: {
      /* If the opcode is TK_TRIGGER, then the expression is a reference
      ** to a column in the new.* or old.* pseudo-tables available to
      ** trigger programs. In this case Expr.iTable is set to 1 for the
      ** new.* pseudo-table, or 0 for the old.* pseudo-table. Expr.iColumn
      ** is set to the column of the pseudo-table to read, or to -1 to
      ** read the rowid field.
      */
      sqlite3TreeViewLine(pView, "%s(%d)", 
          pExpr->iTable ? "NEW" : "OLD", pExpr->iColumn);
      break;
    }
    case TK_CASE: {
      sqlite3TreeViewLine(pView, "CASE");
      sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
      sqlite3TreeViewExprList(pView, pExpr->x.pList, 0, 0);
      break;
    }
#ifndef SQLITE_OMIT_TRIGGER
    case TK_RAISE: {
      const char *zType = "unk";
      switch( pExpr->affinity ){
        case OE_Rollback:   zType = "rollback";  break;
        case OE_Abort:      zType = "abort";     break;
        case OE_Fail:       zType = "fail";      break;
        case OE_Ignore:     zType = "ignore";    break;
      }
      sqlite3TreeViewLine(pView, "RAISE %s(%Q)", zType, pExpr->u.zToken);
      break;
    }
#endif
    default: {
      sqlite3TreeViewLine(pView, "op=%d", pExpr->op);
      break;
    }
  }
  if( zBinOp ){
    sqlite3TreeViewLine(pView, "%s%s", zBinOp, zFlgs);
    sqlite3TreeViewExpr(pView, pExpr->pLeft, 1);
    sqlite3TreeViewExpr(pView, pExpr->pRight, 0);
  }else if( zUniOp ){
    sqlite3TreeViewLine(pView, "%s%s", zUniOp, zFlgs);
    sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
  }
  sqlite3TreeViewPop(pView);
}

/*
** Generate a human-readable explanation of an expression list.
*/
SQLITE_PRIVATE void sqlite3TreeViewExprList(




  TreeView *pView,
  const ExprList *pList,
  u8 moreToFollow,
  const char *zLabel
){
  int i;
  pView = sqlite3TreeViewPush(pView, moreToFollow);
  if( zLabel==0 || zLabel[0]==0 ) zLabel = "LIST";
  if( pList==0 ){
    sqlite3TreeViewLine(pView, "%s (empty)", zLabel);
  }else{
    sqlite3TreeViewLine(pView, "%s", zLabel);
    for(i=0; i<pList->nExpr; i++){
      sqlite3TreeViewExpr(pView, pList->a[i].pExpr, i<pList->nExpr-1);
    }
  }
  sqlite3TreeViewPop(pView);
}

#endif /* SQLITE_DEBUG */

/************** End of treeview.c ********************************************/
/************** Begin file random.c ******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
................................................................................
     /*  55 */ "OpenWrite"        OpHelp("root=P2 iDb=P3"),
     /*  56 */ "OpenAutoindex"    OpHelp("nColumn=P2"),
     /*  57 */ "OpenEphemeral"    OpHelp("nColumn=P2"),
     /*  58 */ "SorterOpen"       OpHelp(""),
     /*  59 */ "SequenceTest"     OpHelp("if( cursor[P1].ctr++ ) pc = P2"),
     /*  60 */ "OpenPseudo"       OpHelp("P3 columns in r[P2]"),
     /*  61 */ "Close"            OpHelp(""),
     /*  62 */ "ColumnsUsed"      OpHelp(""),
     /*  63 */ "SeekLT"           OpHelp("key=r[P3@P4]"),
     /*  64 */ "SeekLE"           OpHelp("key=r[P3@P4]"),
     /*  65 */ "SeekGE"           OpHelp("key=r[P3@P4]"),
     /*  66 */ "SeekGT"           OpHelp("key=r[P3@P4]"),
     /*  67 */ "Seek"             OpHelp("intkey=r[P2]"),
     /*  68 */ "NoConflict"       OpHelp("key=r[P3@P4]"),
     /*  69 */ "NotFound"         OpHelp("key=r[P3@P4]"),
     /*  70 */ "Found"            OpHelp("key=r[P3@P4]"),

     /*  71 */ "Or"               OpHelp("r[P3]=(r[P1] || r[P2])"),
     /*  72 */ "And"              OpHelp("r[P3]=(r[P1] && r[P2])"),
     /*  73 */ "NotExists"        OpHelp("intkey=r[P3]"),
     /*  74 */ "Sequence"         OpHelp("r[P2]=cursor[P1].ctr++"),
     /*  75 */ "NewRowid"         OpHelp("r[P2]=rowid"),

     /*  76 */ "IsNull"           OpHelp("if r[P1]==NULL goto P2"),
     /*  77 */ "NotNull"          OpHelp("if r[P1]!=NULL goto P2"),
     /*  78 */ "Ne"               OpHelp("if r[P1]!=r[P3] goto P2"),
     /*  79 */ "Eq"               OpHelp("if r[P1]==r[P3] goto P2"),
     /*  80 */ "Gt"               OpHelp("if r[P1]>r[P3] goto P2"),
     /*  81 */ "Le"               OpHelp("if r[P1]<=r[P3] goto P2"),
     /*  82 */ "Lt"               OpHelp("if r[P1]<r[P3] goto P2"),
     /*  83 */ "Ge"               OpHelp("if r[P1]>=r[P3] goto P2"),
     /*  84 */ "Insert"           OpHelp("intkey=r[P3] data=r[P2]"),
     /*  85 */ "BitAnd"           OpHelp("r[P3]=r[P1]&r[P2]"),
     /*  86 */ "BitOr"            OpHelp("r[P3]=r[P1]|r[P2]"),
     /*  87 */ "ShiftLeft"        OpHelp("r[P3]=r[P2]<<r[P1]"),
     /*  88 */ "ShiftRight"       OpHelp("r[P3]=r[P2]>>r[P1]"),
     /*  89 */ "Add"              OpHelp("r[P3]=r[P1]+r[P2]"),
     /*  90 */ "Subtract"         OpHelp("r[P3]=r[P2]-r[P1]"),
     /*  91 */ "Multiply"         OpHelp("r[P3]=r[P1]*r[P2]"),
     /*  92 */ "Divide"           OpHelp("r[P3]=r[P2]/r[P1]"),
     /*  93 */ "Remainder"        OpHelp("r[P3]=r[P2]%r[P1]"),
     /*  94 */ "Concat"           OpHelp("r[P3]=r[P2]+r[P1]"),
     /*  95 */ "InsertInt"        OpHelp("intkey=P3 data=r[P2]"),
     /*  96 */ "BitNot"           OpHelp("r[P1]= ~r[P1]"),
     /*  97 */ "String8"          OpHelp("r[P2]='P4'"),
     /*  98 */ "Delete"           OpHelp(""),
     /*  99 */ "ResetCount"       OpHelp(""),
     /* 100 */ "SorterCompare"    OpHelp("if key(P1)!=trim(r[P3],P4) goto P2"),
     /* 101 */ "SorterData"       OpHelp("r[P2]=data"),
     /* 102 */ "RowKey"           OpHelp("r[P2]=key"),
     /* 103 */ "RowData"          OpHelp("r[P2]=data"),
     /* 104 */ "Rowid"            OpHelp("r[P2]=rowid"),
     /* 105 */ "NullRow"          OpHelp(""),
     /* 106 */ "Last"             OpHelp(""),
     /* 107 */ "SorterSort"       OpHelp(""),
     /* 108 */ "Sort"             OpHelp(""),
     /* 109 */ "Rewind"           OpHelp(""),
     /* 110 */ "SorterInsert"     OpHelp(""),
     /* 111 */ "IdxInsert"        OpHelp("key=r[P2]"),
     /* 112 */ "IdxDelete"        OpHelp("key=r[P2@P3]"),
     /* 113 */ "IdxRowid"         OpHelp("r[P2]=rowid"),
     /* 114 */ "IdxLE"            OpHelp("key=r[P3@P4]"),
     /* 115 */ "IdxGT"            OpHelp("key=r[P3@P4]"),
     /* 116 */ "IdxLT"            OpHelp("key=r[P3@P4]"),
     /* 117 */ "IdxGE"            OpHelp("key=r[P3@P4]"),
     /* 118 */ "Destroy"          OpHelp(""),
     /* 119 */ "Clear"            OpHelp(""),
     /* 120 */ "ResetSorter"      OpHelp(""),
     /* 121 */ "CreateIndex"      OpHelp("r[P2]=root iDb=P1"),
     /* 122 */ "CreateTable"      OpHelp("r[P2]=root iDb=P1"),
     /* 123 */ "ParseSchema"      OpHelp(""),
     /* 124 */ "LoadAnalysis"     OpHelp(""),
     /* 125 */ "DropTable"        OpHelp(""),
     /* 126 */ "DropIndex"        OpHelp(""),
     /* 127 */ "DropTrigger"      OpHelp(""),
     /* 128 */ "IntegrityCk"      OpHelp(""),
     /* 129 */ "RowSetAdd"        OpHelp("rowset(P1)=r[P2]"),
     /* 130 */ "RowSetRead"       OpHelp("r[P3]=rowset(P1)"),
     /* 131 */ "RowSetTest"       OpHelp("if r[P3] in rowset(P1) goto P2"),
     /* 132 */ "Program"          OpHelp(""),

     /* 133 */ "Real"             OpHelp("r[P2]=P4"),
     /* 134 */ "Param"            OpHelp(""),
     /* 135 */ "FkCounter"        OpHelp("fkctr[P1]+=P2"),
     /* 136 */ "FkIfZero"         OpHelp("if fkctr[P1]==0 goto P2"),
     /* 137 */ "MemMax"           OpHelp("r[P1]=max(r[P1],r[P2])"),
     /* 138 */ "IfPos"            OpHelp("if r[P1]>0 goto P2"),
     /* 139 */ "IfNeg"            OpHelp("r[P1]+=P3, if r[P1]<0 goto P2"),
     /* 140 */ "IfNotZero"        OpHelp("if r[P1]!=0 then r[P1]+=P3, goto P2"),
     /* 141 */ "DecrJumpZero"     OpHelp("if (--r[P1])==0 goto P2"),
     /* 142 */ "JumpZeroIncr"     OpHelp("if (r[P1]++)==0 ) goto P2"),
     /* 143 */ "AggFinal"         OpHelp("accum=r[P1] N=P2"),
     /* 144 */ "IncrVacuum"       OpHelp(""),
     /* 145 */ "Expire"           OpHelp(""),
     /* 146 */ "TableLock"        OpHelp("iDb=P1 root=P2 write=P3"),
     /* 147 */ "VBegin"           OpHelp(""),
     /* 148 */ "VCreate"          OpHelp(""),
     /* 149 */ "VDestroy"         OpHelp(""),
     /* 150 */ "VOpen"            OpHelp(""),
     /* 151 */ "VColumn"          OpHelp("r[P3]=vcolumn(P2)"),
     /* 152 */ "VNext"            OpHelp(""),
     /* 153 */ "VRename"          OpHelp(""),
     /* 154 */ "Pagecount"        OpHelp(""),
     /* 155 */ "MaxPgcnt"         OpHelp(""),
     /* 156 */ "Init"             OpHelp("Start at P2"),
     /* 157 */ "Noop"             OpHelp(""),
     /* 158 */ "Explain"          OpHelp(""),
  };
  return azName[i];
}
#endif

/************** End of opcodes.c *********************************************/
/************** Begin file os_unix.c *****************************************/
................................................................................
  int szPage;                         /* Size of every page in this cache */
  int szExtra;                        /* Size of extra space for each page */
  u8 bPurgeable;                      /* True if pages are on backing store */
  u8 eCreate;                         /* eCreate value for for xFetch() */
  int (*xStress)(void*,PgHdr*);       /* Call to try make a page clean */
  void *pStress;                      /* Argument to xStress */
  sqlite3_pcache *pCache;             /* Pluggable cache module */

};

/********************************** Linked List Management ********************/

/* Allowed values for second argument to pcacheManageDirtyList() */
#define PCACHE_DIRTYLIST_REMOVE   1    /* Remove pPage from dirty list */
#define PCACHE_DIRTYLIST_ADD      2    /* Add pPage to the dirty list */
................................................................................

/*
** Wrapper around the pluggable caches xUnpin method. If the cache is
** being used for an in-memory database, this function is a no-op.
*/
static void pcacheUnpin(PgHdr *p){
  if( p->pCache->bPurgeable ){



    sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 0);
  }
}

/*
** Compute the number of pages of cache requested.  p->szCache is the
** cache size requested by the "PRAGMA cache_size" statement.
................................................................................
    );
    if( pNew==0 ) return SQLITE_NOMEM;
    sqlite3GlobalConfig.pcache2.xCachesize(pNew, numberOfCachePages(pCache));
    if( pCache->pCache ){
      sqlite3GlobalConfig.pcache2.xDestroy(pCache->pCache);
    }
    pCache->pCache = pNew;

    pCache->szPage = szPage;
  }
  return SQLITE_OK;
}

/*
** Try to obtain a page from the cache.
................................................................................
  if( !pPgHdr->pPage ){
    return pcacheFetchFinishWithInit(pCache, pgno, pPage);
  }
  if( 0==pPgHdr->nRef ){
    pCache->nRef++;
  }
  pPgHdr->nRef++;



  return pPgHdr;
}

/*
** Decrement the reference count on a page. If the page is clean and the
** reference count drops to 0, then it is made eligible for recycling.
*/
................................................................................
*/
SQLITE_PRIVATE void sqlite3PcacheDrop(PgHdr *p){
  assert( p->nRef==1 );
  if( p->flags&PGHDR_DIRTY ){
    pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE);
  }
  p->pCache->nRef--;



  sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 1);
}

/*
** Make sure the page is marked as dirty. If it isn't dirty already,
** make it so.
*/
................................................................................
      */
      assert( p->pgno>0 );
      if( ALWAYS(p->pgno>pgno) ){
        assert( p->flags&PGHDR_DIRTY );
        sqlite3PcacheMakeClean(p);
      }
    }
    if( pgno==0 && pCache->nRef ){
      sqlite3_pcache_page *pPage1;
      pPage1 = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache,1,0);
      if( ALWAYS(pPage1) ){  /* Page 1 is always available in cache, because
                             ** pCache->nRef>0 */
        memset(pPage1->pBuf, 0, pCache->szPage);
        pgno = 1;
      }
    }
    sqlite3GlobalConfig.pcache2.xTruncate(pCache->pCache, pgno+1);
  }
}

/*
** Close a cache.
................................................................................
** compiling for systems that do not support real WSD.
*/
#define pcache1 (GLOBAL(struct PCacheGlobal, pcache1_g))

/*
** Macros to enter and leave the PCache LRU mutex.
*/
#if !defined(SQLITE_ENABLE_MEMORY_MANAGEMENT) || SQLITE_THREADSAFE==0
# define pcache1EnterMutex(X)  assert((X)->mutex==0)
# define pcache1LeaveMutex(X)  assert((X)->mutex==0)
# define PCACHE1_MIGHT_USE_GROUP_MUTEX 0
#else
# define pcache1EnterMutex(X) sqlite3_mutex_enter((X)->mutex)
# define pcache1LeaveMutex(X) sqlite3_mutex_leave((X)->mutex)
# define PCACHE1_MIGHT_USE_GROUP_MUTEX 1
#endif

/******************************************************************************/
/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/

/*
** This function is called during initialization if a static buffer is 
** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE
................................................................................
/*
** This function is used internally to remove the page pPage from the 
** PGroup LRU list, if is part of it. If pPage is not part of the PGroup
** LRU list, then this function is a no-op.
**
** The PGroup mutex must be held when this function is called.
*/
static PgHdr1 *pcache1PinPage(PgHdr1 *pPage){
  PCache1 *pCache;


  assert( pPage!=0 );
  assert( pPage->isPinned==0 );
  pCache = pPage->pCache;

  assert( pPage->pLruNext || pPage==pCache->pGroup->pLruTail );
  assert( pPage->pLruPrev || pPage==pCache->pGroup->pLruHead );
  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
  if( pPage->pLruPrev ){
    pPage->pLruPrev->pLruNext = pPage->pLruNext;
  }else{
    pCache->pGroup->pLruHead = pPage->pLruNext;
  }
  if( pPage->pLruNext ){
    pPage->pLruNext->pLruPrev = pPage->pLruPrev;
  }else{
    pCache->pGroup->pLruTail = pPage->pLruPrev;
  }
  pPage->pLruNext = 0;
  pPage->pLruPrev = 0;
  pPage->isPinned = 1;
  pCache->nRecyclable--;
  return pPage;
}


/*
** Remove the page supplied as an argument from the hash table 
** (PCache1.apHash structure) that it is currently stored in.
**
................................................................................
/*
** Implementation of the sqlite3_pcache.xInit method.
*/
static int pcache1Init(void *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  assert( pcache1.isInit==0 );
  memset(&pcache1, 0, sizeof(pcache1));
#if SQLITE_THREADSAFE
  if( sqlite3GlobalConfig.bCoreMutex ){
    pcache1.grp.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PMEM);
  }
#endif
  pcache1.grp.mxPinned = 10;
  pcache1.isInit = 1;
  return SQLITE_OK;
}

/*
** Implementation of the sqlite3_pcache.xShutdown method.
................................................................................
    }
  }

  /* Step 5. If a usable page buffer has still not been found, 
  ** attempt to allocate a new one. 
  */
  if( !pPage ){
    if( createFlag==1 ){ sqlite3BeginBenignMalloc(); }
    pPage = pcache1AllocPage(pCache);
    if( createFlag==1 ){ sqlite3EndBenignMalloc(); }
  }

  if( pPage ){
    unsigned int h = iKey % pCache->nHash;
    pCache->nPage++;
    pPage->iKey = iKey;
    pPage->pNext = pCache->apHash[h];
................................................................................
**           unnecessary pages cache entry allocations
**
**      then attempt to recycle a page from the LRU list. If it is the right
**      size, return the recycled buffer. Otherwise, free the buffer and
**      proceed to step 5. 
**
**   5. Otherwise, allocate and return a new page buffer.
**
** There are two versions of this routine.  pcache1FetchWithMutex() is
** the general case.  pcache1FetchNoMutex() is a faster implementation for
** the common case where pGroup->mutex is NULL.  The pcache1Fetch() wrapper
** invokes the appropriate routine.
*/

static PgHdr1 *pcache1FetchNoMutex(
  sqlite3_pcache *p, 
  unsigned int iKey, 
  int createFlag
){
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage = 0;









  /* Step 1: Search the hash table for an existing entry. */
  pPage = pCache->apHash[iKey % pCache->nHash];
  while( pPage && pPage->iKey!=iKey ){ pPage = pPage->pNext; }

  /* Step 2: Abort if no existing page is found and createFlag is 0 */
  if( pPage ){
    if( !pPage->isPinned ){
      return pcache1PinPage(pPage);
    }else{
      return pPage;
    }
  }else if( createFlag ){
    /* Steps 3, 4, and 5 implemented by this subroutine */
    return pcache1FetchStage2(pCache, iKey, createFlag);
  }else{
    return 0;
  }
}
#if PCACHE1_MIGHT_USE_GROUP_MUTEX
static PgHdr1 *pcache1FetchWithMutex(
  sqlite3_pcache *p, 
  unsigned int iKey, 
  int createFlag
){
  PCache1 *pCache = (PCache1 *)p;
  PgHdr1 *pPage;

  pcache1EnterMutex(pCache->pGroup);
  pPage = pcache1FetchNoMutex(p, iKey, createFlag);
  assert( pPage==0 || pCache->iMaxKey>=iKey );
  pcache1LeaveMutex(pCache->pGroup);
  return pPage;
}
#endif
static sqlite3_pcache_page *pcache1Fetch(
  sqlite3_pcache *p, 
  unsigned int iKey, 
  int createFlag
){
#if PCACHE1_MIGHT_USE_GROUP_MUTEX || defined(SQLITE_DEBUG)
  PCache1 *pCache = (PCache1 *)p;
#endif

  assert( offsetof(PgHdr1,page)==0 );
  assert( pCache->bPurgeable || createFlag!=1 );
  assert( pCache->bPurgeable || pCache->nMin==0 );
  assert( pCache->bPurgeable==0 || pCache->nMin==10 );
  assert( pCache->nMin==0 || pCache->bPurgeable );
  assert( pCache->nHash>0 );
#if PCACHE1_MIGHT_USE_GROUP_MUTEX
  if( pCache->pGroup->mutex ){
    return (sqlite3_pcache_page*)pcache1FetchWithMutex(p, iKey, createFlag);
  }else
#endif
  {
    return (sqlite3_pcache_page*)pcache1FetchNoMutex(p, iKey, createFlag);
  }
}


/*
** Implementation of the sqlite3_pcache.xUnpin method.
**
** Mark a page as unpinned (eligible for asynchronous recycling).
................................................................................
** small cells will be rare, but they are possible.
*/
#define MX_CELL(pBt) ((pBt->pageSize-8)/6)

/* Forward declarations */
typedef struct MemPage MemPage;
typedef struct BtLock BtLock;
typedef struct CellInfo CellInfo;

/*
** This is a magic string that appears at the beginning of every
** SQLite database in order to identify the file as a real database.
**
** You can change this value at compile-time by specifying a
** -DSQLITE_FILE_HEADER="..." on the compiler command-line.  The
................................................................................
                       ** non-overflow cell */
  u8 *apOvfl[5];       /* Pointers to the body of overflow cells */
  BtShared *pBt;       /* Pointer to BtShared that this page is part of */
  u8 *aData;           /* Pointer to disk image of the page data */
  u8 *aDataEnd;        /* One byte past the end of usable data */
  u8 *aCellIdx;        /* The cell index area */
  DbPage *pDbPage;     /* Pager page handle */
  u16 (*xCellSize)(MemPage*,u8*);             /* cellSizePtr method */
  void (*xParseCell)(MemPage*,u8*,CellInfo*); /* btreeParseCell method */
  Pgno pgno;           /* Page number for this page */
};

/*
** The in-memory image of a disk page has the auxiliary information appended
** to the end.  EXTRA_SIZE is the number of bytes of space needed to hold
** that extra information.
................................................................................
*/
struct Btree {
  sqlite3 *db;       /* The database connection holding this btree */
  BtShared *pBt;     /* Sharable content of this btree */
  u8 inTrans;        /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
  u8 sharable;       /* True if we can share pBt with another db */
  u8 locked;         /* True if db currently has pBt locked */
  u8 hasIncrblobCur; /* True if there are one or more Incrblob cursors */
  int wantToLock;    /* Number of nested calls to sqlite3BtreeEnter() */
  int nBackup;       /* Number of backup operations reading this btree */
  u32 iDataVersion;  /* Combines with pBt->pPager->iDataVersion */
  Btree *pNext;      /* List of other sharable Btrees from the same db */
  Btree *pPrev;      /* Back pointer of the same list */
#ifndef SQLITE_OMIT_SHARED_CACHE
  BtLock lock;       /* Object used to lock page 1 */
................................................................................
#define BTS_PENDING          0x0040   /* Waiting for read-locks to clear */

/*
** An instance of the following structure is used to hold information
** about a cell.  The parseCellPtr() function fills in this structure
** based on information extract from the raw disk page.
*/

struct CellInfo {
  i64 nKey;      /* The key for INTKEY tables, or nPayload otherwise */
  u8 *pPayload;  /* Pointer to the start of payload */
  u32 nPayload;  /* Bytes of payload */
  u16 nLocal;    /* Amount of payload held locally, not on overflow */
  u16 iOverflow; /* Offset to overflow page number.  Zero if no overflow */
  u16 nSize;     /* Size of the cell content on the main b-tree page */
................................................................................
*/
static void invalidateIncrblobCursors(
  Btree *pBtree,          /* The database file to check */
  i64 iRow,               /* The rowid that might be changing */
  int isClearTable        /* True if all rows are being deleted */
){
  BtCursor *p;
  if( pBtree->hasIncrblobCur==0 ) return;
  assert( sqlite3BtreeHoldsMutex(pBtree) );
  pBtree->hasIncrblobCur = 0;
  for(p=pBtree->pBt->pCursor; p; p=p->pNext){
    if( (p->curFlags & BTCF_Incrblob)!=0 ){
      pBtree->hasIncrblobCur = 1;
      if( isClearTable || p->info.nKey==iRow ){

        p->eState = CURSOR_INVALID;
      }
    }
  }
}

#else
  /* Stub function when INCRBLOB is omitted */
  #define invalidateIncrblobCursors(x,y,z)
................................................................................
** the page, 1 means the second cell, and so forth) return a pointer
** to the cell content.
**
** This routine works only for pages that do not contain overflow cells.
*/
#define findCell(P,I) \
  ((P)->aData + ((P)->maskPage & get2byte(&(P)->aCellIdx[2*(I)])))



/*
** This is common tail processing for btreeParseCellPtr() and
** btreeParseCellPtrIndex() for the case when the cell does not fit entirely
** on a single B-tree page.  Make necessary adjustments to the CellInfo
** structure.
*/
static SQLITE_NOINLINE void btreeParseCellAdjustSizeForOverflow(
  MemPage *pPage,         /* Page containing the cell */
  u8 *pCell,              /* Pointer to the cell text. */
  CellInfo *pInfo         /* Fill in this structure */

){
  /* If the payload will not fit completely on the local page, we have
  ** to decide how much to store locally and how much to spill onto
  ** overflow pages.  The strategy is to minimize the amount of unused
  ** space on overflow pages while keeping the amount of local storage
  ** in between minLocal and maxLocal.
  **
  ** Warning:  changing the way overflow payload is distributed in any
  ** way will result in an incompatible file format.
  */
  int minLocal;  /* Minimum amount of payload held locally */
  int maxLocal;  /* Maximum amount of payload held locally */
  int surplus;   /* Overflow payload available for local storage */


  minLocal = pPage->minLocal;
  maxLocal = pPage->maxLocal;
  surplus = minLocal + (pInfo->nPayload - minLocal)%(pPage->pBt->usableSize-4);
  testcase( surplus==maxLocal );
  testcase( surplus==maxLocal+1 );
  if( surplus <= maxLocal ){
    pInfo->nLocal = (u16)surplus;
  }else{
    pInfo->nLocal = (u16)minLocal;
  }
  pInfo->iOverflow = (u16)(&pInfo->pPayload[pInfo->nLocal] - pCell);
  pInfo->nSize = pInfo->iOverflow + 4;
}



/*
** The following routines are implementations of the MemPage.xParseCell()
** method.
**
** Parse a cell content block and fill in the CellInfo structure.



**
** btreeParseCellPtr()        =>   table btree leaf nodes
** btreeParseCellNoPayload()  =>   table btree internal nodes
** btreeParseCellPtrIndex()   =>   index btree nodes
**
** There is also a wrapper function btreeParseCell() that works for
** all MemPage types and that references the cell by index rather than
** by pointer.
*/
static void btreeParseCellPtrNoPayload(
  MemPage *pPage,         /* Page containing the cell */
  u8 *pCell,              /* Pointer to the cell text. */
  CellInfo *pInfo         /* Fill in this structure */
){
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( pPage->leaf==0 );
  assert( pPage->noPayload );
  assert( pPage->childPtrSize==4 );
  pInfo->nSize = 4 + getVarint(&pCell[4], (u64*)&pInfo->nKey);
  pInfo->nPayload = 0;
  pInfo->nLocal = 0;
  pInfo->iOverflow = 0;
  pInfo->pPayload = 0;
  return;
}
static void btreeParseCellPtr(
  MemPage *pPage,         /* Page containing the cell */
  u8 *pCell,              /* Pointer to the cell text. */
  CellInfo *pInfo         /* Fill in this structure */
){
  u8 *pIter;              /* For scanning through pCell */
  u32 nPayload;           /* Number of bytes of cell payload */
  u64 iKey;               /* Extracted Key value */

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( pPage->leaf==0 || pPage->leaf==1 );
  assert( pPage->intKeyLeaf || pPage->noPayload );
  assert( pPage->noPayload==0 );
  assert( pPage->intKeyLeaf );
  assert( pPage->childPtrSize==0 );
  pIter = pCell;

  /* The next block of code is equivalent to:
  **
  **     pIter += getVarint32(pIter, nPayload);
  **
  ** The code is inlined to avoid a function call.
  */
  nPayload = *pIter;
  if( nPayload>=0x80 ){
    u8 *pEnd = &pIter[8];
    nPayload &= 0x7f;
    do{
      nPayload = (nPayload<<7) | (*++pIter & 0x7f);
    }while( (*pIter)>=0x80 && pIter<pEnd );
  }
  pIter++;

  /* The next block of code is equivalent to:
  **
  **     pIter += getVarint(pIter, (u64*)&pInfo->nKey);



  **
  ** The code is inlined to avoid a function call.
  */
  iKey = *pIter;
  if( iKey>=0x80 ){
    u8 *pEnd = &pIter[7];
    iKey &= 0x7f;
    while(1){
      iKey = (iKey<<7) | (*++pIter & 0x7f);
      if( (*pIter)<0x80 ) break;
      if( pIter>=pEnd ){
        iKey = (iKey<<8) | *++pIter;
        break;
      }
    }
  }
  pIter++;

  pInfo->nKey = *(i64*)&iKey;
  pInfo->nPayload = nPayload;
  pInfo->pPayload = pIter;
  testcase( nPayload==pPage->maxLocal );
  testcase( nPayload==pPage->maxLocal+1 );
  if( nPayload<=pPage->maxLocal ){
    /* This is the (easy) common case where the entire payload fits
    ** on the local page.  No overflow is required.
    */
    pInfo->nSize = nPayload + (u16)(pIter - pCell);
    if( pInfo->nSize<4 ) pInfo->nSize = 4;
    pInfo->nLocal = (u16)nPayload;
    pInfo->iOverflow = 0;


  }else{
    btreeParseCellAdjustSizeForOverflow(pPage, pCell, pInfo);
  }
}
static void btreeParseCellPtrIndex(
  MemPage *pPage,         /* Page containing the cell */
  u8 *pCell,              /* Pointer to the cell text. */
  CellInfo *pInfo         /* Fill in this structure */
){
  u8 *pIter;              /* For scanning through pCell */
  u32 nPayload;           /* Number of bytes of cell payload */

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( pPage->leaf==0 || pPage->leaf==1 );
  assert( pPage->intKeyLeaf==0 );
  assert( pPage->noPayload==0 );
  pIter = pCell + pPage->childPtrSize;

  nPayload = *pIter;
  if( nPayload>=0x80 ){
    u8 *pEnd = &pIter[8];
    nPayload &= 0x7f;
    do{
      nPayload = (nPayload<<7) | (*++pIter & 0x7f);
    }while( *(pIter)>=0x80 && pIter<pEnd );
  }
  pIter++;
  pInfo->nKey = nPayload;
  pInfo->nPayload = nPayload;
  pInfo->pPayload = pIter;
  testcase( nPayload==pPage->maxLocal );
  testcase( nPayload==pPage->maxLocal+1 );
  if( nPayload<=pPage->maxLocal ){
    /* This is the (easy) common case where the entire payload fits
    ** on the local page.  No overflow is required.
    */
    pInfo->nSize = nPayload + (u16)(pIter - pCell);
    if( pInfo->nSize<4 ) pInfo->nSize = 4;
    pInfo->nLocal = (u16)nPayload;
    pInfo->iOverflow = 0;
  }else{
    btreeParseCellAdjustSizeForOverflow(pPage, pCell, pInfo);
























  }
}
static void btreeParseCell(
  MemPage *pPage,         /* Page containing the cell */
  int iCell,              /* The cell index.  First cell is 0 */
  CellInfo *pInfo         /* Fill in this structure */
){
  pPage->xParseCell(pPage, findCell(pPage, iCell), pInfo);
}

/*
** The following routines are implementations of the MemPage.xCellSize
** method.
**
** Compute the total number of bytes that a Cell needs in the cell
** data area of the btree-page.  The return number includes the cell
** data header and the local payload, but not any overflow page or
** the space used by the cell pointer.
**
** cellSizePtrNoPayload()    =>   table internal nodes
** cellSizePtr()             =>   all index nodes & table leaf nodes
*/
static u16 cellSizePtr(MemPage *pPage, u8 *pCell){
  u8 *pIter = pCell + pPage->childPtrSize; /* For looping over bytes of pCell */
  u8 *pEnd;                                /* End mark for a varint */
  u32 nSize;                               /* Size value to return */

#ifdef SQLITE_DEBUG
  /* The value returned by this function should always be the same as
  ** the (CellInfo.nSize) value found by doing a full parse of the
  ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of
  ** this function verifies that this invariant is not violated. */
  CellInfo debuginfo;
  pPage->xParseCell(pPage, pCell, &debuginfo);
#endif

  assert( pPage->noPayload==0 );





  nSize = *pIter;
  if( nSize>=0x80 ){
    pEnd = &pIter[8];
    nSize &= 0x7f;
    do{
      nSize = (nSize<<7) | (*++pIter & 0x7f);
    }while( *(pIter)>=0x80 && pIter<pEnd );
  }
  pIter++;
  if( pPage->intKey ){
................................................................................
      nSize = minLocal;
    }
    nSize += 4 + (u16)(pIter - pCell);
  }
  assert( nSize==debuginfo.nSize || CORRUPT_DB );
  return (u16)nSize;
}
static u16 cellSizePtrNoPayload(MemPage *pPage, u8 *pCell){
  u8 *pIter = pCell + 4; /* For looping over bytes of pCell */
  u8 *pEnd;              /* End mark for a varint */

#ifdef SQLITE_DEBUG
  /* The value returned by this function should always be the same as
  ** the (CellInfo.nSize) value found by doing a full parse of the
  ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of
  ** this function verifies that this invariant is not violated. */
  CellInfo debuginfo;
  pPage->xParseCell(pPage, pCell, &debuginfo);
#endif

  assert( pPage->childPtrSize==4 );
  pEnd = pIter + 9;
  while( (*pIter++)&0x80 && pIter<pEnd );
  assert( debuginfo.nSize==(u16)(pIter - pCell) || CORRUPT_DB );
  return (u16)(pIter - pCell);
}


#ifdef SQLITE_DEBUG
/* This variation on cellSizePtr() is used inside of assert() statements
** only. */
static u16 cellSize(MemPage *pPage, int iCell){
  return pPage->xCellSize(pPage, findCell(pPage, iCell));
}
#endif

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** If the cell pCell, part of page pPage contains a pointer
** to an overflow page, insert an entry into the pointer-map
** for the overflow page.
*/
static void ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell, int *pRC){
  CellInfo info;
  if( *pRC ) return;
  assert( pCell!=0 );
  pPage->xParseCell(pPage, pCell, &info);
  if( info.iOverflow ){
    Pgno ovfl = get4byte(&pCell[info.iOverflow]);
    ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno, pRC);
  }
}
#endif

................................................................................
    /* These conditions have already been verified in btreeInitPage()
    ** if PRAGMA cell_size_check=ON.
    */
    if( pc<iCellFirst || pc>iCellLast ){
      return SQLITE_CORRUPT_BKPT;
    }
    assert( pc>=iCellFirst && pc<=iCellLast );
    size = pPage->xCellSize(pPage, &src[pc]);
    cbrk -= size;
    if( cbrk<iCellFirst || pc+size>usableSize ){
      return SQLITE_CORRUPT_BKPT;
    }
    assert( cbrk+size<=usableSize && cbrk>=iCellFirst );
    testcase( cbrk+size==usableSize );
    testcase( pc+size==usableSize );
................................................................................
** from the free-list.
**
** If no suitable space can be found on the free-list, return NULL.
**
** This function may detect corruption within pPg.  If corruption is
** detected then *pRc is set to SQLITE_CORRUPT and NULL is returned.
**
** Slots on the free list that are between 1 and 3 bytes larger than nByte
** will be ignored if adding the extra space to the fragmentation count
** causes the fragmentation count to exceed 60.
*/
static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){
  const int hdr = pPg->hdrOffset;
  u8 * const aData = pPg->aData;
  int iAddr = hdr + 1;
  int pc = get2byte(&aData[iAddr]);
  int x;
  int usableSize = pPg->pBt->usableSize;


  assert( pc>0 );
  do{
    int size;            /* Size of the free slot */
    /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of
    ** increasing offset. */
    if( pc>usableSize-4 || pc<iAddr+4 ){
      *pRc = SQLITE_CORRUPT_BKPT;
      return 0;
    }
    /* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each
    ** freeblock form a big-endian integer which is the size of the freeblock
    ** in bytes, including the 4-byte header. */
    size = get2byte(&aData[pc+2]);

    if( (x = size - nByte)>=0 ){
      testcase( x==4 );
      testcase( x==3 );
      if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){
        *pRc = SQLITE_CORRUPT_BKPT;
        return 0;
      }else if( x<4 ){
        /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total
        ** number of bytes in fragments may not exceed 60. */
        if( aData[hdr+7]>57 ) return 0;



        /* Remove the slot from the free-list. Update the number of
        ** fragmented bytes within the page. */
        memcpy(&aData[iAddr], &aData[pc], 2);
        aData[hdr+7] += (u8)x;



      }else{
        /* The slot remains on the free-list. Reduce its size to account
         ** for the portion used by the new allocation. */
        put2byte(&aData[pc+2], x);
      }
      return &aData[pc + x];
    }
    iAddr = pc;
    pc = get2byte(&aData[pc]);
  }while( pc );

  return 0;
}

/*
** Allocate nByte bytes of space from within the B-Tree page passed
** as the first argument. Write into *pIdx the index into pPage->aData[]
................................................................................
  gap = pPage->cellOffset + 2*pPage->nCell;
  assert( gap<=65536 );
  /* EVIDENCE-OF: R-29356-02391 If the database uses a 65536-byte page size
  ** and the reserved space is zero (the usual value for reserved space)
  ** then the cell content offset of an empty page wants to be 65536.
  ** However, that integer is too large to be stored in a 2-byte unsigned
  ** integer, so a value of 0 is used in its place. */
  top = get2byte(&data[hdr+5]);
  assert( top<=(int)pPage->pBt->usableSize ); /* Prevent by getAndInitPage() */
  if( gap>top ){
    if( top==0 && pPage->pBt->usableSize==65536 ){
      top = 65536;
    }else{
      return SQLITE_CORRUPT_BKPT;
    }
  }

  /* If there is enough space between gap and top for one more cell pointer
  ** array entry offset, and if the freelist is not empty, then search the
  ** freelist looking for a free slot big enough to satisfy the request.
  */
  testcase( gap+2==top );
  testcase( gap+1==top );
  testcase( gap==top );
  if( (data[hdr+2] || data[hdr+1]) && gap+2<=top ){

    u8 *pSpace = pageFindSlot(pPage, nByte, &rc);


    if( pSpace ){
      assert( pSpace>=data && (pSpace - data)<65536 );
      *pIdx = (int)(pSpace - data);
      return SQLITE_OK;
    }else if( rc ){
      return rc;
    }
  }

  /* The request could not be fulfilled using a freelist slot.  Check
  ** to see if defragmentation is necessary.
  */
  testcase( gap+2+nByte==top );
  if( gap+2+nByte>top ){

    assert( pPage->nCell>0 || CORRUPT_DB );
    rc = defragmentPage(pPage);
    if( rc ) return rc;
    top = get2byteNotZero(&data[hdr+5]);
    assert( gap+nByte<=top );
  }

................................................................................
      iPtr = iFreeBlk;
    }
    if( iFreeBlk>iLast ) return SQLITE_CORRUPT_BKPT;
    assert( iFreeBlk>iPtr || iFreeBlk==0 );
  
    /* At this point:
    **    iFreeBlk:   First freeblock after iStart, or zero if none
    **    iPtr:       The address of a pointer to iFreeBlk
    **
    ** Check to see if iFreeBlk should be coalesced onto the end of iStart.
    */
    if( iFreeBlk && iEnd+3>=iFreeBlk ){
      nFrag = iFreeBlk - iEnd;
      if( iEnd>iFreeBlk ) return SQLITE_CORRUPT_BKPT;
      iEnd = iFreeBlk + get2byte(&data[iFreeBlk+2]);
      if( iEnd > pPage->pBt->usableSize ) return SQLITE_CORRUPT_BKPT;
      iSize = iEnd - iStart;
      iFreeBlk = get2byte(&data[iFreeBlk]);
    }
  
    /* If iPtr is another freeblock (that is, if iPtr is not the freelist
    ** pointer in the page header) then check to see if iStart should be
    ** coalesced onto the end of iPtr.
................................................................................
  BtShared *pBt;     /* A copy of pPage->pBt */

  assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  pPage->leaf = (u8)(flagByte>>3);  assert( PTF_LEAF == 1<<3 );
  flagByte &= ~PTF_LEAF;
  pPage->childPtrSize = 4-4*pPage->leaf;
  pPage->xCellSize = cellSizePtr;
  pBt = pPage->pBt;
  if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){
    /* EVIDENCE-OF: R-03640-13415 A value of 5 means the page is an interior
    ** table b-tree page. */
    assert( (PTF_LEAFDATA|PTF_INTKEY)==5 );
    /* EVIDENCE-OF: R-20501-61796 A value of 13 means the page is a leaf
    ** table b-tree page. */
    assert( (PTF_LEAFDATA|PTF_INTKEY|PTF_LEAF)==13 );
    pPage->intKey = 1;
    if( pPage->leaf ){
      pPage->intKeyLeaf = 1;
      pPage->noPayload = 0;
      pPage->xParseCell = btreeParseCellPtr;
    }else{
      pPage->intKeyLeaf = 0;
      pPage->noPayload = 1;
      pPage->xCellSize = cellSizePtrNoPayload;
      pPage->xParseCell = btreeParseCellPtrNoPayload;
    }
    pPage->maxLocal = pBt->maxLeaf;
    pPage->minLocal = pBt->minLeaf;
  }else if( flagByte==PTF_ZERODATA ){
    /* EVIDENCE-OF: R-27225-53936 A value of 2 means the page is an interior
    ** index b-tree page. */
    assert( (PTF_ZERODATA)==2 );
    /* EVIDENCE-OF: R-16571-11615 A value of 10 means the page is a leaf
    ** index b-tree page. */
    assert( (PTF_ZERODATA|PTF_LEAF)==10 );
    pPage->intKey = 0;
    pPage->intKeyLeaf = 0;
    pPage->noPayload = 0;
    pPage->xParseCell = btreeParseCellPtrIndex;
    pPage->maxLocal = pBt->maxLocal;
    pPage->minLocal = pBt->minLocal;
  }else{
    /* EVIDENCE-OF: R-47608-56469 Any other value for the b-tree page type is
    ** an error. */
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
      for(i=0; i<pPage->nCell; i++){
        pc = get2byte(&data[cellOffset+i*2]);
        testcase( pc==iCellFirst );
        testcase( pc==iCellLast );
        if( pc<iCellFirst || pc>iCellLast ){
          return SQLITE_CORRUPT_BKPT;
        }
        sz = pPage->xCellSize(pPage, &data[pc]);
        testcase( pc+sz==usableSize );
        if( pc+sz>usableSize ){
          return SQLITE_CORRUPT_BKPT;
        }
      }
      if( !pPage->leaf ) iCellLast++;
    }  
................................................................................
    if( rc ) return rc;
    nCell = pPage->nCell;

    for(i=0; i<nCell; i++){
      u8 *pCell = findCell(pPage, i);
      if( eType==PTRMAP_OVERFLOW1 ){
        CellInfo info;
        pPage->xParseCell(pPage, pCell, &info);
        if( info.iOverflow
         && pCell+info.iOverflow+3<=pPage->aData+pPage->maskPage
         && iFrom==get4byte(&pCell[info.iOverflow])
        ){
          put4byte(&pCell[info.iOverflow], iTo);
          break;
        }
................................................................................
/*
** Make sure the BtCursor* given in the argument has a valid
** BtCursor.info structure.  If it is not already valid, call
** btreeParseCell() to fill it in.
**
** BtCursor.info is a cache of the information in the current cell.
** Using this cache reduces the number of calls to btreeParseCell().







*/
#ifndef NDEBUG
  static void assertCellInfo(BtCursor *pCur){
    CellInfo info;
    int iPage = pCur->iPage;
    memset(&info, 0, sizeof(info));
    btreeParseCell(pCur->apPage[iPage], pCur->aiIdx[iPage], &info);
    assert( CORRUPT_DB || memcmp(&info, &pCur->info, sizeof(info))==0 );
  }
#else
  #define assertCellInfo(x)
#endif


static SQLITE_NOINLINE void getCellInfo(BtCursor *pCur){
  if( pCur->info.nSize==0 ){
    int iPage = pCur->iPage;

    pCur->curFlags |= BTCF_ValidNKey;
    btreeParseCell(pCur->apPage[iPage],pCur->aiIdx[iPage],&pCur->info);
  }else{
    assertCellInfo(pCur);
  }
}












#ifndef NDEBUG  /* The next routine used only within assert() statements */
/*
** Return true if the given BtCursor is valid.  A valid cursor is one
** that is currently pointing to a row in a (non-empty) table.
** This is a verification routine is used only within assert() statements.
*/
................................................................................
          **
          ** If the record is corrupt, the xRecordCompare routine may read
          ** up to two varints past the end of the buffer. An extra 18 
          ** bytes of padding is allocated at the end of the buffer in
          ** case this happens.  */
          void *pCellKey;
          u8 * const pCellBody = pCell - pPage->childPtrSize;
          pPage->xParseCell(pPage, pCellBody, &pCur->info);
          nCell = (int)pCur->info.nKey;
          testcase( nCell<0 );   /* True if key size is 2^32 or more */
          testcase( nCell==0 );  /* Invalid key size:  0x80 0x80 0x00 */
          testcase( nCell==1 );  /* Invalid key size:  0x80 0x80 0x01 */
          testcase( nCell==2 );  /* Minimum legal index key size */
          if( nCell<2 ){
            rc = SQLITE_CORRUPT_BKPT;
................................................................................
  if( n>=mxPage ){
    return SQLITE_CORRUPT_BKPT;
  }
  if( n>0 ){
    /* There are pages on the freelist.  Reuse one of those pages. */
    Pgno iTrunk;
    u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
    u32 nSearch = 0;   /* Count of the number of search attempts */
    
    /* If eMode==BTALLOC_EXACT and a query of the pointer-map
    ** shows that the page 'nearby' is somewhere on the free-list, then
    ** the entire-list will be searched for that page.
    */
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( eMode==BTALLOC_EXACT ){
................................................................................
      }else{
        /* EVIDENCE-OF: R-59841-13798 The 4-byte big-endian integer at offset 32
        ** stores the page number of the first page of the freelist, or zero if
        ** the freelist is empty. */
        iTrunk = get4byte(&pPage1->aData[32]);
      }
      testcase( iTrunk==mxPage );
      if( iTrunk>mxPage || nSearch++ > n ){
        rc = SQLITE_CORRUPT_BKPT;
      }else{
        rc = btreeGetUnusedPage(pBt, iTrunk, &pTrunk, 0);
      }
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
................................................................................
  CellInfo info;
  Pgno ovflPgno;
  int rc;
  int nOvfl;
  u32 ovflPageSize;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  pPage->xParseCell(pPage, pCell, &info);
  *pnSize = info.nSize;
  if( info.iOverflow==0 ){
    return SQLITE_OK;  /* No overflow pages. Return without doing anything */
  }
  if( pCell+info.iOverflow+3 > pPage->aData+pPage->maskPage ){
    return SQLITE_CORRUPT_BKPT;  /* Cell extends past end of page */
  }
................................................................................
  **
  ** Use a call to btreeParseCellPtr() to verify that the values above
  ** were computed correctly.
  */
#if SQLITE_DEBUG
  {
    CellInfo info;
    pPage->xParseCell(pPage, pCell, &info);
    assert( nHeader=(int)(info.pPayload - pCell) );
    assert( info.nKey==nKey );
    assert( *pnSize == info.nSize );
    assert( spaceLeft == info.nLocal );
    assert( pPrior == &pCell[info.iOverflow] );
  }
#endif
................................................................................
  int sz,           /* Bytes of content in pCell */
  u8 *pTemp,        /* Temp storage space for pCell, if needed */
  Pgno iChild,      /* If non-zero, replace first 4 bytes with this value */
  int *pRC          /* Read and write return code from here */
){
  int idx = 0;      /* Where to write new cell content in data[] */
  int j;            /* Loop counter */



  u8 *data;         /* The content of the whole page */
  u8 *pIns;         /* The point in pPage->aCellIdx[] where no cell inserted */

  if( *pRC ) return;

  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
  assert( MX_CELL(pPage->pBt)<=10921 );
  assert( pPage->nCell<=MX_CELL(pPage->pBt) || CORRUPT_DB );
  assert( pPage->nOverflow<=ArraySize(pPage->apOvfl) );
................................................................................
  assert( ArraySize(pPage->apOvfl)==ArraySize(pPage->aiOvfl) );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  /* The cell should normally be sized correctly.  However, when moving a
  ** malformed cell from a leaf page to an interior page, if the cell size
  ** wanted to be less than 4 but got rounded up to 4 on the leaf, then size
  ** might be less than 8 (leaf-size + pointer) on the interior node.  Hence
  ** the term after the || in the following assert(). */
  assert( sz==pPage->xCellSize(pPage, pCell) || (sz==8 && iChild>0) );
  if( pPage->nOverflow || sz+2>pPage->nFree ){
    if( pTemp ){
      memcpy(pTemp, pCell, sz);
      pCell = pTemp;
    }
    if( iChild ){
      put4byte(pCell, iChild);
    }
    j = pPage->nOverflow++;
    assert( j<(int)(sizeof(pPage->apOvfl)/sizeof(pPage->apOvfl[0])) );
    pPage->apOvfl[j] = pCell;
    pPage->aiOvfl[j] = (u16)i;

    /* When multiple overflows occur, they are always sequential and in
    ** sorted order.  This invariants arise because multiple overflows can
    ** only occur when inserting divider cells into the parent page during
    ** balancing, and the dividers are adjacent and sorted.
    */
    assert( j==0 || pPage->aiOvfl[j-1]<(u16)i ); /* Overflows in sorted order */
    assert( j==0 || i==pPage->aiOvfl[j-1]+1 );   /* Overflows are sequential */
  }else{
    int rc = sqlite3PagerWrite(pPage->pDbPage);
    if( rc!=SQLITE_OK ){
      *pRC = rc;
      return;
    }
    assert( sqlite3PagerIswriteable(pPage->pDbPage) );
    data = pPage->aData;
    assert( &data[pPage->cellOffset]==pPage->aCellIdx );


    rc = allocateSpace(pPage, sz, &idx);
    if( rc ){ *pRC = rc; return; }
    /* The allocateSpace() routine guarantees the following properties
    ** if it returns successfully */
    assert( idx >= 0 );
    assert( idx >= pPage->cellOffset+2*pPage->nCell+2 || CORRUPT_DB );
    assert( idx+sz <= (int)pPage->pBt->usableSize );

    pPage->nFree -= (u16)(2 + sz);
    memcpy(&data[idx], pCell, sz);
    if( iChild ){
      put4byte(&data[idx], iChild);
    }
    pIns = pPage->aCellIdx + i*2;
    memmove(pIns+2, pIns, 2*(pPage->nCell - i));
    put2byte(pIns, idx);
    pPage->nCell++;
    /* increment the cell count */
    if( (++data[pPage->hdrOffset+4])==0 ) data[pPage->hdrOffset+3]++;
    assert( get2byte(&data[pPage->hdrOffset+3])==pPage->nCell );
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pPage->pBt->autoVacuum ){
      /* The cell may contain a pointer to an overflow page. If so, write
      ** the entry for the overflow page into the pointer map.
      */
      ptrmapPutOvflPtr(pPage, pCell, pRC);
    }
#endif
  }
}

/*
** A CellArray object contains a cache of pointers and sizes for a
** consecutive sequence of cells that might be held multiple pages.
*/
typedef struct CellArray CellArray;
struct CellArray {
  int nCell;              /* Number of cells in apCell[] */
  MemPage *pRef;          /* Reference page */
  u8 **apCell;            /* All cells begin balanced */
  u16 *szCell;            /* Local size of all cells in apCell[] */
};

/*
** Make sure the cell sizes at idx, idx+1, ..., idx+N-1 have been
** computed.
*/
static void populateCellCache(CellArray *p, int idx, int N){
  assert( idx>=0 && idx+N<=p->nCell );
  while( N>0 ){
    assert( p->apCell[idx]!=0 );
    if( p->szCell[idx]==0 ){
      p->szCell[idx] = p->pRef->xCellSize(p->pRef, p->apCell[idx]);
    }else{
      assert( CORRUPT_DB ||
              p->szCell[idx]==p->pRef->xCellSize(p->pRef, p->apCell[idx]) );
    }
    idx++;
    N--;
  }
}

/*
** Return the size of the Nth element of the cell array
*/
static SQLITE_NOINLINE u16 computeCellSize(CellArray *p, int N){
  assert( N>=0 && N<p->nCell );
  assert( p->szCell[N]==0 );
  p->szCell[N] = p->pRef->xCellSize(p->pRef, p->apCell[N]);
  return p->szCell[N];
}
static u16 cachedCellSize(CellArray *p, int N){
  assert( N>=0 && N<p->nCell );
  if( p->szCell[N] ) return p->szCell[N];
  return computeCellSize(p, N);
}

/*
** Array apCell[] contains pointers to nCell b-tree page cells. The 
** szCell[] array contains the size in bytes of each cell. This function
** replaces the current contents of page pPg with the contents of the cell
** array.
**
................................................................................
** Some of the cells in apCell[] may currently be stored in pPg. This
** function works around problems caused by this by making a copy of any 
** such cells before overwriting the page data.
**
** The MemPage.nFree field is invalidated by this function. It is the 
** responsibility of the caller to set it correctly.
*/
static int rebuildPage(
  MemPage *pPg,                   /* Edit this page */
  int nCell,                      /* Final number of cells on page */
  u8 **apCell,                    /* Array of cells */
  u16 *szCell                     /* Array of cell sizes */
){
  const int hdr = pPg->hdrOffset;          /* Offset of header on pPg */
  u8 * const aData = pPg->aData;           /* Pointer to data for pPg */
................................................................................
  pData = pEnd;
  for(i=0; i<nCell; i++){
    u8 *pCell = apCell[i];
    if( pCell>aData && pCell<pEnd ){
      pCell = &pTmp[pCell - aData];
    }
    pData -= szCell[i];

    put2byte(pCellptr, (pData - aData));
    pCellptr += 2;
    if( pData < pCellptr ) return SQLITE_CORRUPT_BKPT;
    memcpy(pData, pCell, szCell[i]);
    assert( szCell[i]==pPg->xCellSize(pPg, pCell) || CORRUPT_DB );
    testcase( szCell[i]!=pPg->xCellSize(pPg,pCell) );
  }

  /* The pPg->nFree field is now set incorrectly. The caller will fix it. */
  pPg->nCell = nCell;
  pPg->nOverflow = 0;

  put2byte(&aData[hdr+1], 0);
  put2byte(&aData[hdr+3], pPg->nCell);
  put2byte(&aData[hdr+5], pData - aData);
  aData[hdr+7] = 0x00;
  return SQLITE_OK;
}

/*
** Array apCell[] contains nCell pointers to b-tree cells. Array szCell
** contains the size in bytes of each such cell. This function attempts to 
** add the cells stored in the array to page pPg. If it cannot (because 
** the page needs to be defragmented before the cells will fit), non-zero
................................................................................
** cells in apCell[], then the cells do not fit and non-zero is returned.
*/
static int pageInsertArray(
  MemPage *pPg,                   /* Page to add cells to */
  u8 *pBegin,                     /* End of cell-pointer array */
  u8 **ppData,                    /* IN/OUT: Page content -area pointer */
  u8 *pCellptr,                   /* Pointer to cell-pointer area */
  int iFirst,                     /* Index of first cell to add */
  int nCell,                      /* Number of cells to add to pPg */
  CellArray *pCArray              /* Array of cells */
){
  int i;
  u8 *aData = pPg->aData;
  u8 *pData = *ppData;
  int iEnd = iFirst + nCell;
  assert( CORRUPT_DB || pPg->hdrOffset==0 );    /* Never called on page 1 */
  for(i=iFirst; i<iEnd; i++){

    int sz, rc;
    u8 *pSlot;
    sz = cachedCellSize(pCArray, i);
    if( (aData[1]==0 && aData[2]==0) || (pSlot = pageFindSlot(pPg,sz,&rc))==0 ){
      pData -= sz;
      if( pData<pBegin ) return 1;
      pSlot = pData;
    }
    memcpy(pSlot, pCArray->apCell[i], sz);
    put2byte(pCellptr, (pSlot - aData));
    pCellptr += 2;
  }
  *ppData = pData;
  return 0;
}

................................................................................
** within the body of pPg to the pPg free-list. The cell-pointers and other
** fields of the page are not updated.
**
** This function returns the total number of cells added to the free-list.
*/
static int pageFreeArray(
  MemPage *pPg,                   /* Page to edit */
  int iFirst,                     /* First cell to delete */
  int nCell,                      /* Cells to delete */
  CellArray *pCArray              /* Array of cells */
){
  u8 * const aData = pPg->aData;
  u8 * const pEnd = &aData[pPg->pBt->usableSize];
  u8 * const pStart = &aData[pPg->hdrOffset + 8 + pPg->childPtrSize];
  int nRet = 0;
  int i;
  int iEnd = iFirst + nCell;
  u8 *pFree = 0;
  int szFree = 0;

  for(i=iFirst; i<iEnd; i++){
    u8 *pCell = pCArray->apCell[i];
    if( pCell>=pStart && pCell<pEnd ){
      int sz;
      /* No need to use cachedCellSize() here.  The sizes of all cells that
      ** are to be freed have already been computing while deciding which
      ** cells need freeing */
      sz = pCArray->szCell[i];  assert( sz>0 );
      if( pFree!=(pCell + sz) ){
        if( pFree ){
          assert( pFree>aData && (pFree - aData)<65536 );
          freeSpace(pPg, (u16)(pFree - aData), szFree);
        }
        pFree = pCell;
        szFree = sz;
................................................................................
**
** This routine makes the necessary adjustments to pPg so that it contains
** the correct cells after being balanced.
**
** The pPg->nFree field is invalid when this function returns. It is the
** responsibility of the caller to set it correctly.
*/
static int editPage(
  MemPage *pPg,                   /* Edit this page */
  int iOld,                       /* Index of first cell currently on page */
  int iNew,                       /* Index of new first cell on page */
  int nNew,                       /* Final number of cells on page */
  CellArray *pCArray              /* Array of cells and sizes */

){
  u8 * const aData = pPg->aData;
  const int hdr = pPg->hdrOffset;
  u8 *pBegin = &pPg->aCellIdx[nNew * 2];
  int nCell = pPg->nCell;       /* Cells stored on pPg */
  u8 *pData;
  u8 *pCellptr;
................................................................................
#ifdef SQLITE_DEBUG
  u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager);
  memcpy(pTmp, aData, pPg->pBt->usableSize);
#endif

  /* Remove cells from the start and end of the page */
  if( iOld<iNew ){
    int nShift = pageFreeArray(pPg, iOld, iNew-iOld, pCArray);


    memmove(pPg->aCellIdx, &pPg->aCellIdx[nShift*2], nCell*2);
    nCell -= nShift;
  }
  if( iNewEnd < iOldEnd ){
    nCell -= pageFreeArray(pPg, iNewEnd, iOldEnd - iNewEnd, pCArray);


  }

  pData = &aData[get2byteNotZero(&aData[hdr+5])];
  if( pData<pBegin ) goto editpage_fail;

  /* Add cells to the start of the page */
  if( iNew<iOld ){
    int nAdd = MIN(nNew,iOld-iNew);
    assert( (iOld-iNew)<nNew || nCell==0 || CORRUPT_DB );
    pCellptr = pPg->aCellIdx;
    memmove(&pCellptr[nAdd*2], pCellptr, nCell*2);
    if( pageInsertArray(
          pPg, pBegin, &pData, pCellptr,
          iNew, nAdd, pCArray
    ) ) goto editpage_fail;
    nCell += nAdd;
  }

  /* Add any overflow cells */
  for(i=0; i<pPg->nOverflow; i++){
    int iCell = (iOld + pPg->aiOvfl[i]) - iNew;
    if( iCell>=0 && iCell<nNew ){
      pCellptr = &pPg->aCellIdx[iCell * 2];
      memmove(&pCellptr[2], pCellptr, (nCell - iCell) * 2);
      nCell++;
      if( pageInsertArray(
            pPg, pBegin, &pData, pCellptr,
            iCell+iNew, 1, pCArray
      ) ) goto editpage_fail;
    }
  }

  /* Append cells to the end of the page */
  pCellptr = &pPg->aCellIdx[nCell*2];
  if( pageInsertArray(
        pPg, pBegin, &pData, pCellptr,
        iNew+nCell, nNew-nCell, pCArray
  ) ) goto editpage_fail;

  pPg->nCell = nNew;
  pPg->nOverflow = 0;

  put2byte(&aData[hdr+3], pPg->nCell);
  put2byte(&aData[hdr+5], pData - aData);

#ifdef SQLITE_DEBUG
  for(i=0; i<nNew && !CORRUPT_DB; i++){
    u8 *pCell = pCArray->apCell[i+iNew];
    int iOff = get2byte(&pPg->aCellIdx[i*2]);
    if( pCell>=aData && pCell<&aData[pPg->pBt->usableSize] ){
      pCell = &pTmp[pCell - aData];
    }
    assert( 0==memcmp(pCell, &aData[iOff],
            pCArray->pRef->xCellSize(pCArray->pRef, pCArray->apCell[i+iNew])) );
  }
#endif

  return SQLITE_OK;
 editpage_fail:
  /* Unable to edit this page. Rebuild it from scratch instead. */
  populateCellCache(pCArray, iNew, nNew);
  return rebuildPage(pPg, nNew, &pCArray->apCell[iNew], &pCArray->szCell[iNew]);
}

/*
** The following parameters determine how many adjacent pages get involved
** in a balancing operation.  NN is the number of neighbors on either side
** of the page that participate in the balancing operation.  NB is the
** total number of pages that participate, including the target page and
................................................................................
  */
  rc = allocateBtreePage(pBt, &pNew, &pgnoNew, 0, 0);

  if( rc==SQLITE_OK ){

    u8 *pOut = &pSpace[4];
    u8 *pCell = pPage->apOvfl[0];
    u16 szCell = pPage->xCellSize(pPage, pCell);
    u8 *pStop;

    assert( sqlite3PagerIswriteable(pNew->pDbPage) );
    assert( pPage->aData[0]==(PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF) );
    zeroPage(pNew, PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF);
    rc = rebuildPage(pNew, 1, &pCell, &szCell);
    if( NEVER(rc) ) return rc;
    pNew->nFree = pBt->usableSize - pNew->cellOffset - 2 - szCell;

    /* If this is an auto-vacuum database, update the pointer map
    ** with entries for the new page, and any pointer from the 
    ** cell on the page to an overflow page. If either of these
    ** operations fails, the return code is set, but the contents
    ** of the parent page are still manipulated by thh code below.
................................................................................
    assert( pPage->isInit );

    for(j=0; j<pPage->nCell; j++){
      CellInfo info;
      u8 *z;
     
      z = findCell(pPage, j);
      pPage->xParseCell(pPage, z, &info);
      if( info.iOverflow ){
        Pgno ovfl = get4byte(&z[info.iOverflow]);
        ptrmapGet(pBt, ovfl, &e, &n);
        assert( n==pPage->pgno && e==PTRMAP_OVERFLOW1 );
      }
      if( !pPage->leaf ){
        Pgno child = get4byte(z);
................................................................................
  MemPage *pParent,               /* Parent page of siblings being balanced */
  int iParentIdx,                 /* Index of "the page" in pParent */
  u8 *aOvflSpace,                 /* page-size bytes of space for parent ovfl */
  int isRoot,                     /* True if pParent is a root-page */
  int bBulk                       /* True if this call is part of a bulk load */
){
  BtShared *pBt;               /* The whole database */

  int nMaxCells = 0;           /* Allocated size of apCell, szCell, aFrom. */
  int nNew = 0;                /* Number of pages in apNew[] */
  int nOld;                    /* Number of pages in apOld[] */
  int i, j, k;                 /* Loop counters */
  int nxDiv;                   /* Next divider slot in pParent->aCell[] */
  int rc = SQLITE_OK;          /* The return code */
  u16 leafCorrection;          /* 4 if pPage is a leaf.  0 if not */
  int leafData;                /* True if pPage is a leaf of a LEAFDATA tree */
  int usableSpace;             /* Bytes in pPage beyond the header */
  int pageFlags;               /* Value of pPage->aData[0] */

  int iSpace1 = 0;             /* First unused byte of aSpace1[] */
  int iOvflSpace = 0;          /* First unused byte of aOvflSpace[] */
  int szScratch;               /* Size of scratch memory requested */
  MemPage *apOld[NB];          /* pPage and up to two siblings */
  MemPage *apNew[NB+2];        /* pPage and up to NB siblings after balancing */
  u8 *pRight;                  /* Location in parent of right-sibling pointer */
  u8 *apDiv[NB-1];             /* Divider cells in pParent */
  int cntNew[NB+2];            /* Index in b.paCell[] of cell after i-th page */
  int cntOld[NB+2];            /* Old index in b.apCell[] */
  int szNew[NB+2];             /* Combined size of cells placed on i-th page */


  u8 *aSpace1;                 /* Space for copies of dividers cells */
  Pgno pgno;                   /* Temp var to store a page number in */
  u8 abDone[NB+2];             /* True after i'th new page is populated */
  Pgno aPgno[NB+2];            /* Page numbers of new pages before shuffling */
  Pgno aPgOrder[NB+2];         /* Copy of aPgno[] used for sorting pages */
  u16 aPgFlags[NB+2];          /* flags field of new pages before shuffling */
  CellArray b;                  /* Parsed information on cells being balanced */

  memset(abDone, 0, sizeof(abDone));
  b.nCell = 0;
  b.apCell = 0;
  pBt = pParent->pBt;
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( sqlite3PagerIswriteable(pParent->pDbPage) );

#if 0
  TRACE(("BALANCE: begin page %d child of %d\n", pPage->pgno, pParent->pgno));
#endif
................................................................................
    }
    nMaxCells += 1+apOld[i]->nCell+apOld[i]->nOverflow;
    if( (i--)==0 ) break;

    if( i+nxDiv==pParent->aiOvfl[0] && pParent->nOverflow ){
      apDiv[i] = pParent->apOvfl[0];
      pgno = get4byte(apDiv[i]);
      szNew[i] = pParent->xCellSize(pParent, apDiv[i]);
      pParent->nOverflow = 0;
    }else{
      apDiv[i] = findCell(pParent, i+nxDiv-pParent->nOverflow);
      pgno = get4byte(apDiv[i]);
      szNew[i] = pParent->xCellSize(pParent, apDiv[i]);

      /* Drop the cell from the parent page. apDiv[i] still points to
      ** the cell within the parent, even though it has been dropped.
      ** This is safe because dropping a cell only overwrites the first
      ** four bytes of it, and this function does not need the first
      ** four bytes of the divider cell. So the pointer is safe to use
      ** later on.  
................................................................................
  ** alignment */
  nMaxCells = (nMaxCells + 3)&~3;

  /*
  ** Allocate space for memory structures
  */
  szScratch =
       nMaxCells*sizeof(u8*)                       /* b.apCell */
     + nMaxCells*sizeof(u16)                       /* b.szCell */
     + pBt->pageSize;                              /* aSpace1 */

  /* EVIDENCE-OF: R-28375-38319 SQLite will never request a scratch buffer
  ** that is more than 6 times the database page size. */
  assert( szScratch<=6*(int)pBt->pageSize );
  b.apCell = sqlite3ScratchMalloc( szScratch ); 
  if( b.apCell==0 ){
    rc = SQLITE_NOMEM;
    goto balance_cleanup;
  }
  b.szCell = (u16*)&b.apCell[nMaxCells];
  aSpace1 = (u8*)&b.szCell[nMaxCells];
  assert( EIGHT_BYTE_ALIGNMENT(aSpace1) );

  /*
  ** Load pointers to all cells on sibling pages and the divider cells
  ** into the local b.apCell[] array.  Make copies of the divider cells
  ** into space obtained from aSpace1[]. The divider cells have already
  ** been removed from pParent.
  **
  ** If the siblings are on leaf pages, then the child pointers of the
  ** divider cells are stripped from the cells before they are copied
  ** into aSpace1[].  In this way, all cells in b.apCell[] are without
  ** child pointers.  If siblings are not leaves, then all cell in
  ** b.apCell[] include child pointers.  Either way, all cells in b.apCell[]
  ** are alike.
  **
  ** leafCorrection:  4 if pPage is a leaf.  0 if pPage is not a leaf.
  **       leafData:  1 if pPage holds key+data and pParent holds only keys.
  */
  b.pRef = apOld[0];
  leafCorrection = b.pRef->leaf*4;
  leafData = b.pRef->intKeyLeaf;
  for(i=0; i<nOld; i++){

    MemPage *pOld = apOld[i];
    int limit = pOld->nCell;
    u8 *aData = pOld->aData;
    u16 maskPage = pOld->maskPage;
    u8 *piCell = aData + pOld->cellOffset;
    u8 *piEnd;

    /* Verify that all sibling pages are of the same "type" (table-leaf,
    ** table-interior, index-leaf, or index-interior).
    */
    if( pOld->aData[0]!=apOld[0]->aData[0] ){
      rc = SQLITE_CORRUPT_BKPT;
      goto balance_cleanup;
    }

    /* Load b.apCell[] with pointers to all cells in pOld.  If pOld
    ** constains overflow cells, include them in the b.apCell[] array
    ** in the correct spot.
    **
    ** Note that when there are multiple overflow cells, it is always the
    ** case that they are sequential and adjacent.  This invariant arises
    ** because multiple overflows can only occurs when inserting divider
    ** cells into a parent on a prior balance, and divider cells are always
    ** adjacent and are inserted in order.  There is an assert() tagged
    ** with "NOTE 1" in the overflow cell insertion loop to prove this
    ** invariant.
    **
    ** This must be done in advance.  Once the balance starts, the cell
    ** offset section of the btree page will be overwritten and we will no
    ** long be able to find the cells if a pointer to each cell is not saved
    ** first.
    */
    memset(&b.szCell[b.nCell], 0, sizeof(b.szCell[0])*limit);
    if( pOld->nOverflow>0 ){
      memset(&b.szCell[b.nCell+limit], 0, sizeof(b.szCell[0])*pOld->nOverflow);
      limit = pOld->aiOvfl[0];
      for(j=0; j<limit; j++){



        b.apCell[b.nCell] = aData + (maskPage & get2byte(piCell));
        piCell += 2;
        b.nCell++;
      }



      for(k=0; k<pOld->nOverflow; k++){
        assert( k==0 || pOld->aiOvfl[k-1]+1==pOld->aiOvfl[k] );/* NOTE 1 */
        b.apCell[b.nCell] = pOld->apOvfl[k];
        b.nCell++;
      }
    }
    piEnd = aData + pOld->cellOffset + 2*pOld->nCell;

    while( piCell<piEnd ){
      assert( b.nCell<nMaxCells );


      b.apCell[b.nCell] = aData + (maskPage & get2byte(piCell));
      piCell += 2;
      b.nCell++;
    }

    cntOld[i] = b.nCell;
    if( i<nOld-1 && !leafData){
      u16 sz = (u16)szNew[i];
      u8 *pTemp;
      assert( b.nCell<nMaxCells );
      b.szCell[b.nCell] = sz;
      pTemp = &aSpace1[iSpace1];
      iSpace1 += sz;
      assert( sz<=pBt->maxLocal+23 );
      assert( iSpace1 <= (int)pBt->pageSize );
      memcpy(pTemp, apDiv[i], sz);
      b.apCell[b.nCell] = pTemp+leafCorrection;
      assert( leafCorrection==0 || leafCorrection==4 );
      b.szCell[b.nCell] = b.szCell[b.nCell] - leafCorrection;
      if( !pOld->leaf ){
        assert( leafCorrection==0 );
        assert( pOld->hdrOffset==0 );
        /* The right pointer of the child page pOld becomes the left
        ** pointer of the divider cell */
        memcpy(b.apCell[b.nCell], &pOld->aData[8], 4);
      }else{
        assert( leafCorrection==4 );
        while( b.szCell[b.nCell]<4 ){
          /* Do not allow any cells smaller than 4 bytes. If a smaller cell
          ** does exist, pad it with 0x00 bytes. */
          assert( b.szCell[b.nCell]==3 || CORRUPT_DB );
          assert( b.apCell[b.nCell]==&aSpace1[iSpace1-3] || CORRUPT_DB );
          aSpace1[iSpace1++] = 0x00;
          b.szCell[b.nCell]++;
        }
      }
      b.nCell++;
    }
  }

  /*
  ** Figure out the number of pages needed to hold all b.nCell cells.
  ** Store this number in "k".  Also compute szNew[] which is the total
  ** size of all cells on the i-th page and cntNew[] which is the index
  ** in b.apCell[] of the cell that divides page i from page i+1.  
  ** cntNew[k] should equal b.nCell.
  **
  ** Values computed by this block:
  **
  **           k: The total number of sibling pages
  **    szNew[i]: Spaced used on the i-th sibling page.
  **   cntNew[i]: Index in b.apCell[] and b.szCell[] for the first cell to
  **              the right of the i-th sibling page.
  ** usableSpace: Number of bytes of space available on each sibling.
  ** 
  */
  usableSpace = pBt->usableSize - 12 + leafCorrection;
  for(i=0; i<nOld; i++){
    MemPage *p = apOld[i];
    szNew[i] = usableSpace - p->nFree;
    if( szNew[i]<0 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }
    for(j=0; j<p->nOverflow; j++){
      szNew[i] += 2 + p->xCellSize(p, p->apOvfl[j]);
    }
    cntNew[i] = cntOld[i];
  }
  k = nOld;
  for(i=0; i<k; i++){
    int sz;
    while( szNew[i]>usableSpace ){

      if( i+1>=k ){
        k = i+2;
        if( k>NB+2 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }
        szNew[k-1] = 0;
        cntNew[k-1] = b.nCell;
      }
      sz = 2 + cachedCellSize(&b, cntNew[i]-1);
      szNew[i] -= sz;
      if( !leafData ){
        if( cntNew[i]<b.nCell ){
          sz = 2 + cachedCellSize(&b, cntNew[i]);
        }else{
          sz = 0;
        }
      }
      szNew[i+1] += sz;
      cntNew[i]--;
    }
    while( cntNew[i]<b.nCell ){
      sz = 2 + cachedCellSize(&b, cntNew[i]);
      if( szNew[i]+sz>usableSpace ) break;
      szNew[i] += sz;
      cntNew[i]++;
      if( !leafData ){
        if( cntNew[i]<b.nCell ){
          sz = 2 + cachedCellSize(&b, cntNew[i]);
        }else{
          sz = 0;
        }
      }
      szNew[i+1] -= sz;
    }
    if( cntNew[i]>=b.nCell ){
      k = i+1;
    }else if( cntNew[i] <= (i>0 ? cntNew[i-1] : 0) ){
      rc = SQLITE_CORRUPT_BKPT;
      goto balance_cleanup;
    }
  }




  /*
  ** The packing computed by the previous block is biased toward the siblings
  ** on the left side (siblings with smaller keys). The left siblings are
  ** always nearly full, while the right-most sibling might be nearly empty.
  ** The next block of code attempts to adjust the packing of siblings to
  ** get a better balance.
................................................................................
    int szRight = szNew[i];  /* Size of sibling on the right */
    int szLeft = szNew[i-1]; /* Size of sibling on the left */
    int r;              /* Index of right-most cell in left sibling */
    int d;              /* Index of first cell to the left of right sibling */

    r = cntNew[i-1] - 1;
    d = r + 1 - leafData;
    (void)cachedCellSize(&b, d);
    do{
      assert( d<nMaxCells );
      assert( r<nMaxCells );
      (void)cachedCellSize(&b, r);
      if( szRight!=0


       && (bBulk || szRight+b.szCell[d]+2 > szLeft-(b.szCell[r]+2)) ){
        break;
      }
      szRight += b.szCell[d] + 2;
      szLeft -= b.szCell[r] + 2;
      cntNew[i-1] = r;



      r--;
      d--;
    }while( r>=0 );
    szNew[i] = szRight;
    szNew[i-1] = szLeft;
    if( cntNew[i-1] <= (i>1 ? cntNew[i-2] : 0) ){
      rc = SQLITE_CORRUPT_BKPT;
      goto balance_cleanup;
    }
  }

  /* Sanity check:  For a non-corrupt database file one of the follwing
  ** must be true:
  **    (1) We found one or more cells (cntNew[0])>0), or
  **    (2) pPage is a virtual root page.  A virtual root page is when
  **        the real root page is page 1 and we are the only child of
................................................................................
    }else{
      assert( i>0 );
      rc = allocateBtreePage(pBt, &pNew, &pgno, (bBulk ? 1 : pgno), 0);
      if( rc ) goto balance_cleanup;
      zeroPage(pNew, pageFlags);
      apNew[i] = pNew;
      nNew++;
      cntOld[i] = b.nCell;

      /* Set the pointer-map entry for the new sibling page. */
      if( ISAUTOVACUUM ){
        ptrmapPut(pBt, pNew->pgno, PTRMAP_BTREE, pParent->pgno, &rc);
        if( rc!=SQLITE_OK ){
          goto balance_cleanup;
        }
................................................................................
    MemPage *pNew = apNew[0];
    u8 *aOld = pNew->aData;
    int cntOldNext = pNew->nCell + pNew->nOverflow;
    int usableSize = pBt->usableSize;
    int iNew = 0;
    int iOld = 0;

    for(i=0; i<b.nCell; i++){
      u8 *pCell = b.apCell[i];
      if( i==cntOldNext ){
        MemPage *pOld = (++iOld)<nNew ? apNew[iOld] : apOld[iOld];
        cntOldNext += pOld->nCell + pOld->nOverflow + !leafData;
        aOld = pOld->aData;
      }
      if( i==cntNew[iNew] ){
        pNew = apNew[++iNew];
................................................................................
       || pNew->pgno!=aPgno[iOld]
       || pCell<aOld
       || pCell>=&aOld[usableSize]
      ){
        if( !leafCorrection ){
          ptrmapPut(pBt, get4byte(pCell), PTRMAP_BTREE, pNew->pgno, &rc);
        }
        if( cachedCellSize(&b,i)>pNew->minLocal ){
          ptrmapPutOvflPtr(pNew, pCell, &rc);
        }
        if( rc ) goto balance_cleanup;
      }
    }
  }

  /* Insert new divider cells into pParent. */
  for(i=0; i<nNew-1; i++){
    u8 *pCell;
    u8 *pTemp;
    int sz;
    MemPage *pNew = apNew[i];
    j = cntNew[i];

    assert( j<nMaxCells );
    assert( b.apCell[j]!=0 );
    pCell = b.apCell[j];
    sz = b.szCell[j] + leafCorrection;
    pTemp = &aOvflSpace[iOvflSpace];
    if( !pNew->leaf ){
      memcpy(&pNew->aData[8], pCell, 4);
    }else if( leafData ){
      /* If the tree is a leaf-data tree, and the siblings are leaves, 
      ** then there is no divider cell in b.apCell[]. Instead, the divider 
      ** cell consists of the integer key for the right-most cell of 
      ** the sibling-page assembled above only.
      */
      CellInfo info;
      j--;
      pNew->xParseCell(pNew, b.apCell[j], &info);
      pCell = pTemp;
      sz = 4 + putVarint(&pCell[4], info.nKey);
      pTemp = 0;
    }else{
      pCell -= 4;
      /* Obscure case for non-leaf-data trees: If the cell at pCell was
      ** previously stored on a leaf node, and its reported size was 4
................................................................................
      ** any cell). But it is important to pass the correct size to 
      ** insertCell(), so reparse the cell now.
      **
      ** Note that this can never happen in an SQLite data file, as all
      ** cells are at least 4 bytes. It only happens in b-trees used
      ** to evaluate "IN (SELECT ...)" and similar clauses.
      */
      if( b.szCell[j]==4 ){
        assert(leafCorrection==4);
        sz = pParent->xCellSize(pParent, pCell);
      }
    }
    iOvflSpace += sz;
    assert( sz<=pBt->maxLocal+23 );
    assert( iOvflSpace <= (int)pBt->pageSize );
    insertCell(pParent, nxDiv+i, pCell, sz, pTemp, pNew->pgno, &rc);
    if( rc!=SQLITE_OK ) goto balance_cleanup;
................................................................................
      ** only after iPg+1 has already been updated. */
      assert( cntNew[iPg]>=cntOld[iPg] || abDone[iPg+1] );

      if( iPg==0 ){
        iNew = iOld = 0;
        nNewCell = cntNew[0];
      }else{
        iOld = iPg<nOld ? (cntOld[iPg-1] + !leafData) : b.nCell;
        iNew = cntNew[iPg-1] + !leafData;
        nNewCell = cntNew[iPg] - iNew;
      }

      rc = editPage(apNew[iPg], iOld, iNew, nNewCell, &b);
      if( rc ) goto balance_cleanup;
      abDone[iPg]++;
      apNew[iPg]->nFree = usableSpace-szNew[iPg];
      assert( apNew[iPg]->nOverflow==0 );
      assert( apNew[iPg]->nCell==nNewCell );
    }
  }

................................................................................
      u32 key = get4byte(&apNew[i]->aData[8]);
      ptrmapPut(pBt, key, PTRMAP_BTREE, apNew[i]->pgno, &rc);
    }
  }

  assert( pParent->isInit );
  TRACE(("BALANCE: finished: old=%d new=%d cells=%d\n",
          nOld, nNew, b.nCell));

  /* Free any old pages that were not reused as new pages.
  */
  for(i=nNew; i<nOld; i++){
    freePage(apOld[i], &rc);
  }

................................................................................
  }
#endif

  /*
  ** Cleanup before returning.
  */
balance_cleanup:
  sqlite3ScratchFree(b.apCell);
  for(i=0; i<nOld; i++){
    releasePage(apOld[i]);
  }
  for(i=0; i<nNew; i++){
    releasePage(apNew[i]);
  }

................................................................................
          pCur->pgnoRoot, nKey, nData, pPage->pgno,
          loc==0 ? "overwrite" : "new entry"));
  assert( pPage->isInit );
  newCell = pBt->pTmpSpace;
  assert( newCell!=0 );
  rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, nZero, &szNew);
  if( rc ) goto end_insert;
  assert( szNew==pPage->xCellSize(pPage, newCell) );
  assert( szNew <= MX_CELL_SIZE(pBt) );
  idx = pCur->aiIdx[pCur->iPage];
  if( loc==0 ){
    u16 szOld;
    assert( idx<pPage->nCell );
    rc = sqlite3PagerWrite(pPage->pDbPage);
    if( rc ){
................................................................................
    MemPage *pLeaf = pCur->apPage[pCur->iPage];
    int nCell;
    Pgno n = pCur->apPage[iCellDepth+1]->pgno;
    unsigned char *pTmp;

    pCell = findCell(pLeaf, pLeaf->nCell-1);
    if( pCell<&pLeaf->aData[4] ) return SQLITE_CORRUPT_BKPT;
    nCell = pLeaf->xCellSize(pLeaf, pCell);
    assert( MX_CELL_SIZE(pBt) >= nCell );
    pTmp = pBt->pTmpSpace;
    assert( pTmp!=0 );
    rc = sqlite3PagerWrite(pLeaf->pDbPage);
    insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc);
    dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc);
    if( rc ) return rc;
................................................................................

    /* Check payload overflow pages
    */
    pCheck->zPfx = "On tree page %d cell %d: ";
    pCheck->v1 = iPage;
    pCheck->v2 = i;
    pCell = findCell(pPage,i);
    pPage->xParseCell(pPage, pCell, &info);
    sz = info.nPayload;
    /* For intKey pages, check that the keys are in order.
    */
    if( pPage->intKey ){
      if( i==0 ){
        nMinKey = nMaxKey = info.nKey;
      }else if( info.nKey <= nMaxKey ){
................................................................................
    cellStart = hdr + 12 - 4*pPage->leaf;
    /* EVIDENCE-OF: R-02776-14802 The cell pointer array consists of K 2-byte
    ** integer offsets to the cell contents. */
    for(i=0; i<nCell; i++){
      int pc = get2byte(&data[cellStart+i*2]);
      u32 size = 65536;
      if( pc<=usableSize-4 ){
        size = pPage->xCellSize(pPage, &data[pc]);
      }
      if( (int)(pc+size-1)>=usableSize ){
        pCheck->zPfx = 0;
        checkAppendMsg(pCheck,
            "Corruption detected in cell %d on page %d",i,iPage);
      }else{
        btreeHeapInsert(heap, (pc<<16)|(pc+size-1));
................................................................................
}

/* 
** Mark this cursor as an incremental blob cursor.
*/
SQLITE_PRIVATE void sqlite3BtreeIncrblobCursor(BtCursor *pCur){
  pCur->curFlags |= BTCF_Incrblob;
  pCur->pBtree->hasIncrblobCur = 1;
}
#endif

/*
** Set both the "read version" (single byte at byte offset 18) and 
** "write version" (single byte at byte offset 19) fields in the database
** header to iVersion.
................................................................................
** is forced.  In other words, the value is converted into the desired
** affinity even if that results in loss of data.  This routine is
** used (for example) to implement the SQL "cast()" operator.
*/
SQLITE_PRIVATE void sqlite3VdbeMemCast(Mem *pMem, u8 aff, u8 encoding){
  if( pMem->flags & MEM_Null ) return;
  switch( aff ){
    case SQLITE_AFF_BLOB: {   /* Really a cast to BLOB */
      if( (pMem->flags & MEM_Blob)==0 ){
        sqlite3ValueApplyAffinity(pMem, SQLITE_AFF_TEXT, encoding);
        assert( pMem->flags & MEM_Str || pMem->db->mallocFailed );
        MemSetTypeFlag(pMem, MEM_Blob);
      }else{
        pMem->flags &= ~(MEM_TypeMask&~MEM_Blob);
      }
................................................................................

/*
** Make an shallow copy of pFrom into pTo.  Prior contents of
** pTo are freed.  The pFrom->z field is not duplicated.  If
** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
** and flags gets srcType (either MEM_Ephem or MEM_Static).
*/
static SQLITE_NOINLINE void vdbeClrCopy(Mem *pTo, const Mem *pFrom, int eType){
  vdbeMemClearExternAndSetNull(pTo);
  assert( !VdbeMemDynamic(pTo) );
  sqlite3VdbeMemShallowCopy(pTo, pFrom, eType);
}
SQLITE_PRIVATE void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
  assert( (pFrom->flags & MEM_RowSet)==0 );
  assert( pTo->db==pFrom->db );
  if( VdbeMemDynamic(pTo) ){ vdbeClrCopy(pTo,pFrom,srcType); return; }
  memcpy(pTo, pFrom, MEMCELLSIZE);
  if( (pFrom->flags&MEM_Static)==0 ){
    pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
    assert( srcType==MEM_Ephem || srcType==MEM_Static );
    pTo->flags |= srcType;
  }
}
................................................................................
** pMem->zMalloc space will be allocated if necessary.  The calling routine
** is responsible for making sure that the pMem object is eventually
** destroyed.
**
** If this routine fails for any reason (malloc returns NULL or unable
** to read from the disk) then the pMem is left in an inconsistent state.
*/
static SQLITE_NOINLINE int vdbeMemFromBtreeResize(
  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
  u32 offset,       /* Offset from the start of data to return bytes from. */
  u32 amt,          /* Number of bytes to return. */
  int key,          /* If true, retrieve from the btree key, not data. */
  Mem *pMem         /* OUT: Return data in this Mem structure. */
){
  int rc;
  pMem->flags = MEM_Null;
  if( SQLITE_OK==(rc = sqlite3VdbeMemClearAndResize(pMem, amt+2)) ){
    if( key ){
      rc = sqlite3BtreeKey(pCur, offset, amt, pMem->z);
    }else{
      rc = sqlite3BtreeData(pCur, offset, amt, pMem->z);
    }
    if( rc==SQLITE_OK ){
      pMem->z[amt] = 0;
      pMem->z[amt+1] = 0;
      pMem->flags = MEM_Blob|MEM_Term;
      pMem->n = (int)amt;
    }else{
      sqlite3VdbeMemRelease(pMem);
    }
  }
  return rc;
}
SQLITE_PRIVATE int sqlite3VdbeMemFromBtree(
  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
  u32 offset,       /* Offset from the start of data to return bytes from. */
  u32 amt,          /* Number of bytes to return. */
  int key,          /* If true, retrieve from the btree key, not data. */
  Mem *pMem         /* OUT: Return data in this Mem structure. */
){
................................................................................
  assert( zData!=0 );

  if( offset+amt<=available ){
    pMem->z = &zData[offset];
    pMem->flags = MEM_Blob|MEM_Ephem;
    pMem->n = (int)amt;
  }else{



    rc = vdbeMemFromBtreeResize(pCur, offset, amt, key, pMem);












  }

  return rc;
}

/*
** The pVal argument is known to be a value other than NULL.
................................................................................
    if( ExprHasProperty(pExpr, EP_IntValue) ){
      sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
    }else{
      zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
      if( zVal==0 ) goto no_mem;
      sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
    }
    if( (op==TK_INTEGER || op==TK_FLOAT ) && affinity==SQLITE_AFF_BLOB ){
      sqlite3ValueApplyAffinity(pVal, SQLITE_AFF_NUMERIC, SQLITE_UTF8);
    }else{
      sqlite3ValueApplyAffinity(pVal, affinity, SQLITE_UTF8);
    }
    if( pVal->flags & (MEM_Int|MEM_Real) ) pVal->flags &= ~MEM_Str;
    if( enc!=SQLITE_UTF8 ){
      rc = sqlite3VdbeChangeEncoding(pVal, enc);
................................................................................
SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value *v){
  if( !v ) return;
  sqlite3VdbeMemRelease((Mem *)v);
  sqlite3DbFree(((Mem*)v)->db, v);
}

/*
** The sqlite3ValueBytes() routine returns the number of bytes in the
** sqlite3_value object assuming that it uses the encoding "enc".
** The valueBytes() routine is a helper function.
*/
static SQLITE_NOINLINE int valueBytes(sqlite3_value *pVal, u8 enc){
  return valueToText(pVal, enc)!=0 ? pVal->n : 0;
}
SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value *pVal, u8 enc){
  Mem *p = (Mem*)pVal;
  assert( (p->flags & MEM_Null)==0 || (p->flags & (MEM_Str|MEM_Blob))==0 );
  if( (p->flags & MEM_Str)!=0 && pVal->enc==enc ){
    return p->n;
  }
  if( (p->flags & MEM_Blob)!=0 ){
    if( p->flags & MEM_Zero ){
      return p->n + p->u.nZero;
    }else{
      return p->n;
    }
  }
  if( p->flags & MEM_Null ) return 0;
  return valueBytes(pVal, enc);
}

/************** End of vdbemem.c *********************************************/
/************** Begin file vdbeaux.c *****************************************/
/*
** 2003 September 6
**
................................................................................
  const char *zP4,    /* The P4 operand */
  int p4type          /* P4 operand type */
){
  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
  sqlite3VdbeChangeP4(p, addr, zP4, p4type);
  return addr;
}

/*
** Add an opcode that includes the p4 value with a P4_INT64 type.
*/
SQLITE_PRIVATE int sqlite3VdbeAddOp4Dup8(
  Vdbe *p,            /* Add the opcode to this VM */
  int op,             /* The new opcode */
  int p1,             /* The P1 operand */
  int p2,             /* The P2 operand */
  int p3,             /* The P3 operand */
  const u8 *zP4,      /* The P4 operand */
  int p4type          /* P4 operand type */
){
  char *p4copy = sqlite3DbMallocRaw(sqlite3VdbeDb(p), 8);
  if( p4copy ) memcpy(p4copy, zP4, 8);
  return sqlite3VdbeAddOp4(p, op, p1, p2, p3, p4copy, p4type);
}

/*
** Add an OP_ParseSchema opcode.  This routine is broken out from
** sqlite3VdbeAddOp4() since it needs to also needs to mark all btrees
** as having been used.
**
** The zWhere string must have been obtained from sqlite3_malloc().
................................................................................
**
**   *  OP_Halt with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
**   *  OP_HaltIfNull with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
**   *  OP_Destroy
**   *  OP_VUpdate
**   *  OP_VRename
**   *  OP_FkCounter with P2==0 (immediate foreign key constraint)
**   *  OP_CreateTable and OP_InitCoroutine (for CREATE TABLE AS SELECT ...)
**
** Then check that the value of Parse.mayAbort is true if an
** ABORT may be thrown, or false otherwise. Return true if it does
** match, or false otherwise. This function is intended to be used as
** part of an assert statement in the compiler. Similar to:
**
**   assert( sqlite3VdbeAssertMayAbort(pParse->pVdbe, pParse->mayAbort) );
*/
SQLITE_PRIVATE int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
  int hasAbort = 0;
  int hasFkCounter = 0;
  int hasCreateTable = 0;
  int hasInitCoroutine = 0;
  Op *pOp;
  VdbeOpIter sIter;
  memset(&sIter, 0, sizeof(sIter));
  sIter.v = v;

  while( (pOp = opIterNext(&sIter))!=0 ){
    int opcode = pOp->opcode;
................................................................................
    if( opcode==OP_Destroy || opcode==OP_VUpdate || opcode==OP_VRename 
     || ((opcode==OP_Halt || opcode==OP_HaltIfNull) 
      && ((pOp->p1&0xff)==SQLITE_CONSTRAINT && pOp->p2==OE_Abort))
    ){
      hasAbort = 1;
      break;
    }
    if( opcode==OP_CreateTable ) hasCreateTable = 1;
    if( opcode==OP_InitCoroutine ) hasInitCoroutine = 1;
#ifndef SQLITE_OMIT_FOREIGN_KEY
    if( opcode==OP_FkCounter && pOp->p1==0 && pOp->p2==1 ){
      hasFkCounter = 1;
    }
#endif
  }
  sqlite3DbFree(v->db, sIter.apSub);

  /* Return true if hasAbort==mayAbort. Or if a malloc failure occurred.
  ** If malloc failed, then the while() loop above may not have iterated
  ** through all opcodes and hasAbort may be set incorrectly. Return
  ** true for this case to prevent the assert() in the callers frame
  ** from failing.  */
  return ( v->db->mallocFailed || hasAbort==mayAbort || hasFkCounter
              || (hasCreateTable && hasInitCoroutine) );
}
#endif /* SQLITE_DEBUG - the sqlite3AssertMayAbort() function */

/*
** Loop through the program looking for P2 values that are negative
** on jump instructions.  Each such value is a label.  Resolve the
** label by setting the P2 value to its correct non-zero value.
................................................................................
}
#endif

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
/*
** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter().
*/
static SQLITE_NOINLINE void vdbeLeave(Vdbe *p){
  int i;
  sqlite3 *db;
  Db *aDb;
  int nDb;

  db = p->db;
  aDb = db->aDb;
  nDb = db->nDb;
  for(i=0; i<nDb; i++){
    if( i!=1 && DbMaskTest(p->lockMask,i) && ALWAYS(aDb[i].pBt!=0) ){
      sqlite3BtreeLeave(aDb[i].pBt);
    }
  }
}
SQLITE_PRIVATE void sqlite3VdbeLeave(Vdbe *p){
  if( DbMaskAllZero(p->lockMask) ) return;  /* The common case */
  vdbeLeave(p);
}
#endif

#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
/*
** Print a single opcode.  This routine is used for debugging only.
*/
................................................................................
**    is not possible.  Note that the integer representation is
**    always preferred, even if the affinity is REAL, because
**    an integer representation is more space efficient on disk.
**
** SQLITE_AFF_TEXT:
**    Convert pRec to a text representation.
**
** SQLITE_AFF_BLOB:
**    No-op.  pRec is unchanged.
*/
static void applyAffinity(
  Mem *pRec,          /* The value to apply affinity to */
  char affinity,      /* The affinity to be applied */
  u8 enc              /* Use this text encoding */
){
................................................................................
  assert( p->explain==0 );
  p->pResultSet = 0;
  db->busyHandler.nBusy = 0;
  if( db->u1.isInterrupted ) goto abort_due_to_interrupt;
  sqlite3VdbeIOTraceSql(p);
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  if( db->xProgress ){
    u32 iPrior = p->aCounter[SQLITE_STMTSTATUS_VM_STEP];
    assert( 0 < db->nProgressOps );


    nProgressLimit = db->nProgressOps - (iPrior % db->nProgressOps);



  }
#endif
#ifdef SQLITE_DEBUG
  sqlite3BeginBenignMalloc();
  if( p->pc==0
   && (p->db->flags & (SQLITE_VdbeListing|SQLITE_VdbeEQP|SQLITE_VdbeTrace))!=0
  ){
................................................................................
** <li value="100"> INTEGER
** <li value="101"> REAL
** </ul>
**
** A NULL value is not changed by this routine.  It remains NULL.
*/
case OP_Cast: {                  /* in1 */
  assert( pOp->p2>=SQLITE_AFF_BLOB && pOp->p2<=SQLITE_AFF_REAL );
  testcase( pOp->p2==SQLITE_AFF_TEXT );
  testcase( pOp->p2==SQLITE_AFF_BLOB );
  testcase( pOp->p2==SQLITE_AFF_NUMERIC );
  testcase( pOp->p2==SQLITE_AFF_INTEGER );
  testcase( pOp->p2==SQLITE_AFF_REAL );
  pIn1 = &aMem[pOp->p1];
  memAboutToChange(p, pIn1);
  rc = ExpandBlob(pIn1);
  sqlite3VdbeMemCast(pIn1, pOp->p2, encoding);
................................................................................
** P4 may be a string that is P2 characters long.  The nth character of the
** string indicates the column affinity that should be used for the nth
** field of the index key.
**
** The mapping from character to affinity is given by the SQLITE_AFF_
** macros defined in sqliteInt.h.
**
** If P4 is NULL then all index fields have the affinity BLOB.
*/
case OP_MakeRecord: {
  u8 *zNewRecord;        /* A buffer to hold the data for the new record */
  Mem *pRec;             /* The new record */
  u64 nData;             /* Number of bytes of data space */
  int nHdr;              /* Number of bytes of header space */
  i64 nByte;             /* Data space required for this record */
................................................................................
*/
case OP_Close: {
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  sqlite3VdbeFreeCursor(p, p->apCsr[pOp->p1]);
  p->apCsr[pOp->p1] = 0;
  break;
}

#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
/* Opcode: ColumnsUsed P1 * * P4 *
**
** This opcode (which only exists if SQLite was compiled with
** SQLITE_ENABLE_COLUMN_USED_MASK) identifies which columns of the
** table or index for cursor P1 are used.  P4 is a 64-bit integer
** (P4_INT64) in which the first 63 bits are one for each of the
** first 63 columns of the table or index that are actually used
** by the cursor.  The high-order bit is set if any column after
** the 64th is used.
*/
case OP_ColumnsUsed: {
  VdbeCursor *pC;
  pC = p->apCsr[pOp->p1];
  assert( pC->pCursor );
  pC->maskUsed = *(u64*)pOp->p4.pI64;
  break;
}
#endif

/* Opcode: SeekGE P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as the key.  If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
................................................................................
        if( ExprHasProperty(pItem->pExpr, EP_Agg) ){
          sqlite3ErrorMsg(pParse, "aggregate functions are not allowed in "
              "the GROUP BY clause");
          return WRC_Abort;
        }
      }
    }

    /* If this is part of a compound SELECT, check that it has the right
    ** number of expressions in the select list. */
    if( p->pNext && p->pEList->nExpr!=p->pNext->pEList->nExpr ){
      sqlite3SelectWrongNumTermsError(pParse, p->pNext);
      return WRC_Abort;
    }

    /* Advance to the next term of the compound
    */
    p = p->pPrior;
    nCompound++;
  }

................................................................................
  if( aff1 && aff2 ){
    /* Both sides of the comparison are columns. If one has numeric
    ** affinity, use that. Otherwise use no affinity.
    */
    if( sqlite3IsNumericAffinity(aff1) || sqlite3IsNumericAffinity(aff2) ){
      return SQLITE_AFF_NUMERIC;
    }else{
      return SQLITE_AFF_BLOB;
    }
  }else if( !aff1 && !aff2 ){
    /* Neither side of the comparison is a column.  Compare the
    ** results directly.
    */
    return SQLITE_AFF_BLOB;
  }else{
    /* One side is a column, the other is not. Use the columns affinity. */
    assert( aff1==0 || aff2==0 );
    return (aff1 + aff2);
  }
}

................................................................................
  assert( pExpr->pLeft );
  aff = sqlite3ExprAffinity(pExpr->pLeft);
  if( pExpr->pRight ){
    aff = sqlite3CompareAffinity(pExpr->pRight, aff);
  }else if( ExprHasProperty(pExpr, EP_xIsSelect) ){
    aff = sqlite3CompareAffinity(pExpr->x.pSelect->pEList->a[0].pExpr, aff);
  }else if( !aff ){
    aff = SQLITE_AFF_BLOB;
  }
  return aff;
}

/*
** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.
** idx_affinity is the affinity of an indexed column. Return true
** if the index with affinity idx_affinity may be used to implement
** the comparison in pExpr.
*/
SQLITE_PRIVATE int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity){
  char aff = comparisonAffinity(pExpr);
  switch( aff ){
    case SQLITE_AFF_BLOB:
      return 1;
    case SQLITE_AFF_TEXT:
      return idx_affinity==SQLITE_AFF_TEXT;
    default:
      return sqlite3IsNumericAffinity(idx_affinity);
  }
}
................................................................................
    pNewItem->jointype = pOldItem->jointype;
    pNewItem->iCursor = pOldItem->iCursor;
    pNewItem->addrFillSub = pOldItem->addrFillSub;
    pNewItem->regReturn = pOldItem->regReturn;
    pNewItem->isCorrelated = pOldItem->isCorrelated;
    pNewItem->viaCoroutine = pOldItem->viaCoroutine;
    pNewItem->isRecursive = pOldItem->isRecursive;
    pNewItem->zIndexedBy = sqlite3DbStrDup(db, pOldItem->zIndexedBy);
    pNewItem->notIndexed = pOldItem->notIndexed;
    pNewItem->pIndex = pOldItem->pIndex;
    pTab = pNewItem->pTab = pOldItem->pTab;
    if( pTab ){
      pTab->nRef++;
    }
    pNewItem->pSelect = sqlite3SelectDup(db, pOldItem->pSelect, flags);
................................................................................
** Walker.eCode value determines the type of "constant" we are looking
** for.
**
** These callback routines are used to implement the following:
**
**     sqlite3ExprIsConstant()                  pWalker->eCode==1
**     sqlite3ExprIsConstantNotJoin()           pWalker->eCode==2
**     sqlite3ExprIsTableConstant()             pWalker->eCode==3
**     sqlite3ExprIsConstantOrFunction()        pWalker->eCode==4 or 5
**
** In all cases, the callbacks set Walker.eCode=0 and abort if the expression
** is found to not be a constant.
**
** The sqlite3ExprIsConstantOrFunction() is used for evaluating expressions
** in a CREATE TABLE statement.  The Walker.eCode value is 5 when parsing
................................................................................
** an ON or USING clause.
*/
SQLITE_PRIVATE int sqlite3ExprIsConstantNotJoin(Expr *p){
  return exprIsConst(p, 2, 0);
}

/*
** Walk an expression tree.  Return non-zero if the expression is constant
** for any single row of the table with cursor iCur.  In other words, the
** expression must not refer to any non-deterministic function nor any
** table other than iCur.
*/
SQLITE_PRIVATE int sqlite3ExprIsTableConstant(Expr *p, int iCur){
  return exprIsConst(p, 3, iCur);
}
................................................................................
** This routine is used to determine if the OP_Affinity operation
** can be omitted.  When in doubt return FALSE.  A false negative
** is harmless.  A false positive, however, can result in the wrong
** answer.
*/
SQLITE_PRIVATE int sqlite3ExprNeedsNoAffinityChange(const Expr *p, char aff){
  u8 op;
  if( aff==SQLITE_AFF_BLOB ) return 1;
  while( p->op==TK_UPLUS || p->op==TK_UMINUS ){ p = p->pLeft; }
  op = p->op;
  if( op==TK_REGISTER ) op = p->op2;
  switch( op ){
    case TK_INTEGER: {
      return aff==SQLITE_AFF_INTEGER || aff==SQLITE_AFF_NUMERIC;
    }
................................................................................
        */
        int i;
        ExprList *pList = pExpr->x.pList;
        struct ExprList_item *pItem;
        int r1, r2, r3;

        if( !affinity ){
          affinity = SQLITE_AFF_BLOB;
        }
        if( pKeyInfo ){
          assert( sqlite3KeyInfoIsWriteable(pKeyInfo) );
          pKeyInfo->aColl[0] = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
        }

        /* Loop through each expression in <exprlist>. */
................................................................................
  }
  sqlite3ReleaseTempReg(pParse, r1);
  sqlite3ExprCachePop(pParse);
  VdbeComment((v, "end IN expr"));
}
#endif /* SQLITE_OMIT_SUBQUERY */












#ifndef SQLITE_OMIT_FLOATING_POINT
/*
** Generate an instruction that will put the floating point
** value described by z[0..n-1] into register iMem.
**
** The z[] string will probably not be zero-terminated.  But the 
** z[n] character is guaranteed to be something that does not look
** like the continuation of the number.
*/
static void codeReal(Vdbe *v, const char *z, int negateFlag, int iMem){
  if( ALWAYS(z!=0) ){
    double value;

    sqlite3AtoF(z, &value, sqlite3Strlen30(z), SQLITE_UTF8);
    assert( !sqlite3IsNaN(value) ); /* The new AtoF never returns NaN */
    if( negateFlag ) value = -value;

    sqlite3VdbeAddOp4Dup8(v, OP_Real, 0, iMem, 0, (u8*)&value, P4_REAL);
  }
}
#endif


/*
** Generate an instruction that will put the integer describe by
................................................................................
  }else{
    int c;
    i64 value;
    const char *z = pExpr->u.zToken;
    assert( z!=0 );
    c = sqlite3DecOrHexToI64(z, &value);
    if( c==0 || (c==2 && negFlag) ){

      if( negFlag ){ value = c==2 ? SMALLEST_INT64 : -value; }

      sqlite3VdbeAddOp4Dup8(v, OP_Int64, 0, iMem, 0, (u8*)&value, P4_INT64);
    }else{
#ifdef SQLITE_OMIT_FLOATING_POINT
      sqlite3ErrorMsg(pParse, "oversized integer: %s%s", negFlag ? "-" : "", z);
#else
#ifndef SQLITE_OMIT_HEX_INTEGER
      if( sqlite3_strnicmp(z,"0x",2)==0 ){
        sqlite3ErrorMsg(pParse, "hex literal too big: %s", z);
................................................................................
      }

      /* The UNLIKELY() function is a no-op.  The result is the value
      ** of the first argument.
      */
      if( pDef->funcFlags & SQLITE_FUNC_UNLIKELY ){
        assert( nFarg>=1 );
        inReg = sqlite3ExprCodeTarget(pParse, pFarg->a[0].pExpr, target);
        break;
      }

      for(i=0; i<nFarg; i++){
        if( i<32 && sqlite3ExprIsConstant(pFarg->a[i].pExpr) ){
          testcase( i==31 );
          constMask |= MASKBIT32(i);
................................................................................
  assert( pExpr->op!=TK_REGISTER );
  sqlite3ExprCode(pParse, pExpr, target);
  iMem = ++pParse->nMem;
  sqlite3VdbeAddOp2(v, OP_Copy, target, iMem);
  exprToRegister(pExpr, iMem);
}







































































































































































































































































/*
** Generate code that pushes the value of every element of the given
** expression list into a sequence of registers beginning at target.
**
** Return the number of elements evaluated.
**
** The SQLITE_ECEL_DUP flag prevents the arguments from being
................................................................................
      }
      break;
    }
  }
  sqlite3ReleaseTempReg(pParse, regFree1);
  sqlite3ReleaseTempReg(pParse, regFree2);
}

/*
** Like sqlite3ExprIfFalse() except that a copy is made of pExpr before
** code generation, and that copy is deleted after code generation. This
** ensures that the original pExpr is unchanged.
*/
SQLITE_PRIVATE void sqlite3ExprIfFalseDup(Parse *pParse, Expr *pExpr, int dest,int jumpIfNull){
  sqlite3 *db = pParse->db;
  Expr *pCopy = sqlite3ExprDup(db, pExpr, 0);
  if( db->mallocFailed==0 ){
    sqlite3ExprIfFalse(pParse, pCopy, dest, jumpIfNull);
  }
  sqlite3ExprDelete(db, pCopy);
}


/*
** Do a deep comparison of two expression trees.  Return 0 if the two
** expressions are completely identical.  Return 1 if they differ only
** by a COLLATE operator at the top level.  Return 2 if there are differences
** other than the top-level COLLATE operator.
**
................................................................................

  /* Ensure the default expression is something that sqlite3ValueFromExpr()
  ** can handle (i.e. not CURRENT_TIME etc.)
  */
  if( pDflt ){
    sqlite3_value *pVal = 0;
    int rc;
    rc = sqlite3ValueFromExpr(db, pDflt, SQLITE_UTF8, SQLITE_AFF_BLOB, &pVal);
    assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
    if( rc!=SQLITE_OK ){
      db->mallocFailed = 1;
      return;
    }
    if( !pVal ){
      sqlite3ErrorMsg(pParse, "Cannot add a column with non-constant default");
................................................................................
  ** indices.  Hence, the record number for the table must be allocated
  ** now.
  */
  if( !db->init.busy && (v = sqlite3GetVdbe(pParse))!=0 ){
    int j1;
    int fileFormat;
    int reg1, reg2, reg3;
    sqlite3BeginWriteOperation(pParse, 1, iDb);

#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( isVirtual ){
      sqlite3VdbeAddOp0(v, OP_VBegin);
    }
#endif

................................................................................
    p->aCol = aNew;
  }
  pCol = &p->aCol[p->nCol];
  memset(pCol, 0, sizeof(p->aCol[0]));
  pCol->zName = z;
 
  /* If there is no type specified, columns have the default affinity
  ** 'BLOB'. If there is a type specified, then sqlite3AddColumnType() will
  ** be called next to set pCol->affinity correctly.
  */
  pCol->affinity = SQLITE_AFF_BLOB;
  pCol->szEst = 1;
  p->nCol++;
}

/*
** This routine is called by the parser while in the middle of
** parsing a CREATE TABLE statement.  A "NOT NULL" constraint has
................................................................................
**
** Substring     | Affinity
** --------------------------------
** 'INT'         | SQLITE_AFF_INTEGER
** 'CHAR'        | SQLITE_AFF_TEXT
** 'CLOB'        | SQLITE_AFF_TEXT
** 'TEXT'        | SQLITE_AFF_TEXT
** 'BLOB'        | SQLITE_AFF_BLOB
** 'REAL'        | SQLITE_AFF_REAL
** 'FLOA'        | SQLITE_AFF_REAL
** 'DOUB'        | SQLITE_AFF_REAL
**
** If none of the substrings in the above table are found,
** SQLITE_AFF_NUMERIC is returned.
*/
................................................................................
      zChar = zIn;
    }else if( h==(('c'<<24)+('l'<<16)+('o'<<8)+'b') ){       /* CLOB */
      aff = SQLITE_AFF_TEXT;
    }else if( h==(('t'<<24)+('e'<<16)+('x'<<8)+'t') ){       /* TEXT */
      aff = SQLITE_AFF_TEXT;
    }else if( h==(('b'<<24)+('l'<<16)+('o'<<8)+'b')          /* BLOB */
        && (aff==SQLITE_AFF_NUMERIC || aff==SQLITE_AFF_REAL) ){
      aff = SQLITE_AFF_BLOB;
      if( zIn[0]=='(' ) zChar = zIn;
#ifndef SQLITE_OMIT_FLOATING_POINT
    }else if( h==(('r'<<24)+('e'<<16)+('a'<<8)+'l')          /* REAL */
        && aff==SQLITE_AFF_NUMERIC ){
      aff = SQLITE_AFF_REAL;
    }else if( h==(('f'<<24)+('l'<<16)+('o'<<8)+'a')          /* FLOA */
        && aff==SQLITE_AFF_NUMERIC ){
................................................................................
  }
  sqlite3_snprintf(n, zStmt, "CREATE TABLE ");
  k = sqlite3Strlen30(zStmt);
  identPut(zStmt, &k, p->zName);
  zStmt[k++] = '(';
  for(pCol=p->aCol, i=0; i<p->nCol; i++, pCol++){
    static const char * const azType[] = {
        /* SQLITE_AFF_BLOB    */ "",
        /* SQLITE_AFF_TEXT    */ " TEXT",
        /* SQLITE_AFF_NUMERIC */ " NUM",
        /* SQLITE_AFF_INTEGER */ " INT",
        /* SQLITE_AFF_REAL    */ " REAL"
    };
    int len;
    const char *zType;

    sqlite3_snprintf(n-k, &zStmt[k], zSep);
    k += sqlite3Strlen30(&zStmt[k]);
    zSep = zSep2;
    identPut(zStmt, &k, pCol->zName);
    assert( pCol->affinity-SQLITE_AFF_BLOB >= 0 );
    assert( pCol->affinity-SQLITE_AFF_BLOB < ArraySize(azType) );
    testcase( pCol->affinity==SQLITE_AFF_BLOB );
    testcase( pCol->affinity==SQLITE_AFF_TEXT );
    testcase( pCol->affinity==SQLITE_AFF_NUMERIC );
    testcase( pCol->affinity==SQLITE_AFF_INTEGER );
    testcase( pCol->affinity==SQLITE_AFF_REAL );
    
    zType = azType[pCol->affinity - SQLITE_AFF_BLOB];
    len = sqlite3Strlen30(zType);
    assert( pCol->affinity==SQLITE_AFF_BLOB 
            || pCol->affinity==sqlite3AffinityType(zType, 0) );
    memcpy(&zStmt[k], zType, len);
    k += len;
    assert( k<=n );
  }
  sqlite3_snprintf(n-k, &zStmt[k], "%s", zEnd);
  return zStmt;
................................................................................
      int addrInsLoop;    /* Top of the loop for inserting rows */
      Table *pSelTab;     /* A table that describes the SELECT results */

      regYield = ++pParse->nMem;
      regRec = ++pParse->nMem;
      regRowid = ++pParse->nMem;
      assert(pParse->nTab==1);
      sqlite3MayAbort(pParse);
      sqlite3VdbeAddOp3(v, OP_OpenWrite, 1, pParse->regRoot, iDb);
      sqlite3VdbeChangeP5(v, OPFLAG_P2ISREG);
      pParse->nTab = 2;
      addrTop = sqlite3VdbeCurrentAddr(v) + 1;
      sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, addrTop);
      sqlite3SelectDestInit(&dest, SRT_Coroutine, regYield);
      sqlite3Select(pParse, pSelect, &dest);
................................................................................
  int i;
  struct SrcList_item *pItem;
  if( pList==0 ) return;
  for(pItem=pList->a, i=0; i<pList->nSrc; i++, pItem++){
    sqlite3DbFree(db, pItem->zDatabase);
    sqlite3DbFree(db, pItem->zName);
    sqlite3DbFree(db, pItem->zAlias);
    sqlite3DbFree(db, pItem->zIndexedBy);
    sqlite3DeleteTable(db, pItem->pTab);
    sqlite3SelectDelete(db, pItem->pSelect);
    sqlite3ExprDelete(db, pItem->pOn);
    sqlite3IdListDelete(db, pItem->pUsing);
  }
  sqlite3DbFree(db, pList);
}
................................................................................
** Add an INDEXED BY or NOT INDEXED clause to the most recently added 
** element of the source-list passed as the second argument.
*/
SQLITE_PRIVATE void sqlite3SrcListIndexedBy(Parse *pParse, SrcList *p, Token *pIndexedBy){
  assert( pIndexedBy!=0 );
  if( p && ALWAYS(p->nSrc>0) ){
    struct SrcList_item *pItem = &p->a[p->nSrc-1];
    assert( pItem->notIndexed==0 && pItem->zIndexedBy==0 );
    if( pIndexedBy->n==1 && !pIndexedBy->z ){
      /* A "NOT INDEXED" clause was supplied. See parse.y 
      ** construct "indexed_opt" for details. */
      pItem->notIndexed = 1;
    }else{
      pItem->zIndexedBy = sqlite3NameFromToken(pParse->db, pIndexedBy);
    }
  }
}

/*
** When building up a FROM clause in the parser, the join operator
** is initially attached to the left operand.  But the code generator
................................................................................
  int nCol;

  if( piPartIdxLabel ){
    if( pIdx->pPartIdxWhere ){
      *piPartIdxLabel = sqlite3VdbeMakeLabel(v);
      pParse->iPartIdxTab = iDataCur;
      sqlite3ExprCachePush(pParse);
      sqlite3ExprIfFalseDup(pParse, pIdx->pPartIdxWhere, *piPartIdxLabel, 
                            SQLITE_JUMPIFNULL);
    }else{
      *piPartIdxLabel = 0;
    }
  }
  nCol = (prefixOnly && pIdx->uniqNotNull) ? pIdx->nKeyCol : pIdx->nColumn;
  regBase = sqlite3GetTempRange(pParse, nCol);
  if( pPrior && (regBase!=regPrior || pPrior->pPartIdxWhere) ) pPrior = 0;
................................................................................
  u8 matchOne;
  u8 matchSet;
  u8 noCase;
};

/*
** For LIKE and GLOB matching on EBCDIC machines, assume that every
** character is exactly one byte in size.  Also, provde the Utf8Read()
** macro for fast reading of the next character in the common case where
** the next character is ASCII.
*/
#if defined(SQLITE_EBCDIC)
# define sqlite3Utf8Read(A)        (*((*A)++))
# define Utf8Read(A)               (*(A++))

#else


# define Utf8Read(A)               (A[0]<0x80?*(A++):sqlite3Utf8Read(&A))
#endif

static const struct compareInfo globInfo = { '*', '?', '[', 0 };
/* The correct SQL-92 behavior is for the LIKE operator to ignore
** case.  Thus  'a' LIKE 'A' would be true. */
static const struct compareInfo likeInfoNorm = { '%', '_',   0, 1 };
/* If SQLITE_CASE_SENSITIVE_LIKE is defined, then the LIKE operator
................................................................................
**      '%'       Matches any sequence of zero or more characters
**
***     '_'       Matches any one character
**
**      Ec        Where E is the "esc" character and c is any other
**                character, including '%', '_', and esc, match exactly c.
**
** The comments within this routine usually assume glob matching.
**
** This routine is usually quick, but can be N**2 in the worst case.
*/
static int patternCompare(
  const u8 *zPattern,              /* The glob pattern */
  const u8 *zString,               /* The string to compare against the glob */
  const struct compareInfo *pInfo, /* Information about how to do the compare */
................................................................................
  /* The GLOB operator does not have an ESCAPE clause.  And LIKE does not
  ** have the matchSet operator.  So we either have to look for one or
  ** the other, never both.  Hence the single variable matchOther is used
  ** to store the one we have to look for.
  */
  matchOther = esc ? esc : pInfo->matchSet;

  while( (c = Utf8Read(zPattern))!=0 ){
    if( c==matchAll ){  /* Match "*" */
      /* Skip over multiple "*" characters in the pattern.  If there
      ** are also "?" characters, skip those as well, but consume a
      ** single character of the input string for each "?" skipped */

      while( (c=Utf8Read(zPattern)) == matchAll || c == matchOne ){
        if( c==matchOne && sqlite3Utf8Read(&zString)==0 ){
          return 0;
        }
      }
      if( c==0 ){
        return 1;   /* "*" at the end of the pattern matches */
      }else if( c==matchOther ){
................................................................................
          cx = c;
        }
        while( (c2 = *(zString++))!=0 ){
          if( c2!=c && c2!=cx ) continue;
          if( patternCompare(zPattern,zString,pInfo,esc) ) return 1;
        }
      }else{
        while( (c2 = Utf8Read(zString))!=0 ){
          if( c2!=c ) continue;
          if( patternCompare(zPattern,zString,pInfo,esc) ) return 1;
        }
      }
      return 0;
    }
    if( c==matchOther ){
................................................................................
        }
        if( c2==0 || (seen ^ invert)==0 ){
          return 0;
        }
        continue;
      }
    }
    c2 = Utf8Read(zString);
    if( c==c2 ) continue;
    if( noCase && c<0x80 && c2<0x80 && sqlite3Tolower(c)==sqlite3Tolower(c2) ){
      continue;
    }
    if( c==matchOne && zPattern!=zEscaped && c2!=0 ) continue;
    return 0;
  }
................................................................................
/*
** Return a pointer to the column affinity string associated with index
** pIdx. A column affinity string has one character for each column in 
** the table, according to the affinity of the column:
**
**  Character      Column affinity
**  ------------------------------
**  'A'            BLOB
**  'B'            TEXT
**  'C'            NUMERIC
**  'D'            INTEGER
**  'F'            REAL
**
** An extra 'D' is appended to the end of the string to cover the
** rowid that appears as the last column in every index.
................................................................................
  }
 
  return pIdx->zColAff;
}

/*
** Compute the affinity string for table pTab, if it has not already been
** computed.  As an optimization, omit trailing SQLITE_AFF_BLOB affinities.
**
** If the affinity exists (if it is no entirely SQLITE_AFF_BLOB values) and
** if iReg>0 then code an OP_Affinity opcode that will set the affinities
** for register iReg and following.  Or if affinities exists and iReg==0,
** then just set the P4 operand of the previous opcode (which should  be
** an OP_MakeRecord) to the affinity string.
**
** A column affinity string has one character per column:
**
**  Character      Column affinity
**  ------------------------------
**  'A'            BLOB
**  'B'            TEXT
**  'C'            NUMERIC
**  'D'            INTEGER
**  'E'            REAL
*/
SQLITE_PRIVATE void sqlite3TableAffinity(Vdbe *v, Table *pTab, int iReg){
  int i;
................................................................................
    }

    for(i=0; i<pTab->nCol; i++){
      zColAff[i] = pTab->aCol[i].affinity;
    }
    do{
      zColAff[i--] = 0;
    }while( i>=0 && zColAff[i]==SQLITE_AFF_BLOB );
    pTab->zColAff = zColAff;
  }
  i = sqlite3Strlen30(zColAff);
  if( i ){
    if( iReg ){
      sqlite3VdbeAddOp4(v, OP_Affinity, iReg, i, 0, zColAff, i);
    }else{
................................................................................
    iThisCur = iIdxCur+ix;
    addrUniqueOk = sqlite3VdbeMakeLabel(v);

    /* Skip partial indices for which the WHERE clause is not true */
    if( pIdx->pPartIdxWhere ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, aRegIdx[ix]);
      pParse->ckBase = regNewData+1;
      sqlite3ExprIfFalseDup(pParse, pIdx->pPartIdxWhere, addrUniqueOk,
                            SQLITE_JUMPIFNULL);
      pParse->ckBase = 0;
    }

    /* Create a record for this index entry as it should appear after
    ** the insert or update.  Store that record in the aRegIdx[ix] register
    */
    regIdx = sqlite3GetTempRange(pParse, pIdx->nColumn);
................................................................................
  void *(*realloc64)(void*,sqlite3_uint64);
  void (*reset_auto_extension)(void);
  void (*result_blob64)(sqlite3_context*,const void*,sqlite3_uint64,
                        void(*)(void*));
  void (*result_text64)(sqlite3_context*,const char*,sqlite3_uint64,
                         void(*)(void*), unsigned char);
  int (*strglob)(const char*,const char*);
  /* Version 3.8.11 and later */
  sqlite3_value *(*value_dup)(const sqlite3_value*);
  void (*value_free)(sqlite3_value*);
};

/*
** The following macros redefine the API routines so that they are
** redirected through the global sqlite3_api structure.
**
................................................................................
  sqlite3_load_extension,
  sqlite3_malloc64,
  sqlite3_msize,
  sqlite3_realloc64,
  sqlite3_reset_auto_extension,
  sqlite3_result_blob64,
  sqlite3_result_text64,
  sqlite3_strglob,
  /* Version 3.8.11 and later */
  (sqlite3_value*(*)(const sqlite3_value*))sqlite3_value_dup,
  sqlite3_value_free
};

/*
** Attempt to load an SQLite extension library contained in the file
** zFile.  The entry point is zProc.  zProc may be 0 in which case a
** default entry point name (sqlite3_extension_init) is used.  Use
** of the default name is recommended.
................................................................................
/*
** Trace output macros
*/
#if SELECTTRACE_ENABLED
/***/ int sqlite3SelectTrace = 0;
# define SELECTTRACE(K,P,S,X)  \
  if(sqlite3SelectTrace&(K))   \
    sqlite3DebugPrintf("%*s%s.%p: ",(P)->nSelectIndent*2-2,"",\
        (S)->zSelName,(S)),\
    sqlite3DebugPrintf X
#else
# define SELECTTRACE(K,P,S,X)
#endif


/*
................................................................................
*/
static void setJoinExpr(Expr *p, int iTable){
  while( p ){
    ExprSetProperty(p, EP_FromJoin);
    assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
    ExprSetVVAProperty(p, EP_NoReduce);
    p->iRightJoinTable = (i16)iTable;
    if( p->op==TK_FUNCTION && p->x.pList ){
      int i;
      for(i=0; i<p->x.pList->nExpr; i++){
        setJoinExpr(p->x.pList->a[i].pExpr, iTable);
      }
    }
    setJoinExpr(p->pLeft, iTable);
    p = p->pRight;
  } 
}

/*
** This routine processes the join information for a SELECT statement.
................................................................................
      case WHERE_DISTINCT_UNIQUE: {
        sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
        break;
      }

      default: {
        assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED );
        codeDistinct(pParse, pDistinct->tabTnct, iContinue, nResultCol,
                     regResult);
        break;
      }
    }
    if( pSort==0 ){
      codeOffset(v, p->iOffset, iContinue);
    }
  }
................................................................................
      if( eDest==SRT_DistFifo ){
        /* If the destination is DistFifo, then cursor (iParm+1) is open
        ** on an ephemeral index. If the current row is already present
        ** in the index, do not write it to the output. If not, add the
        ** current row to the index and proceed with writing it to the
        ** output table as well.  */
        int addr = sqlite3VdbeCurrentAddr(v) + 4;
        sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0);
        VdbeCoverage(v);
        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r1);
        assert( pSort==0 );
      }
#endif
      if( pSort ){
        pushOntoSorter(pParse, pSort, p, r1+nPrefixReg, 1, nPrefixReg);
      }else{
................................................................................
** The declaration type for any expression other than a column is NULL.
**
** This routine has either 3 or 6 parameters depending on whether or not
** the SQLITE_ENABLE_COLUMN_METADATA compile-time option is used.
*/
#ifdef SQLITE_ENABLE_COLUMN_METADATA
# define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,C,D,E,F)
#else /* if !defined(SQLITE_ENABLE_COLUMN_METADATA) */
# define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,F)
#endif
static const char *columnTypeImpl(
  NameContext *pNC, 
  Expr *pExpr,
#ifdef SQLITE_ENABLE_COLUMN_METADATA
  const char **pzOrigDb,
  const char **pzOrigTab,
  const char **pzOrigCol,
#endif
  u8 *pEstWidth
){
  char const *zType = 0;
  int j;
  u8 estWidth = 1;
#ifdef SQLITE_ENABLE_COLUMN_METADATA
  char const *zOrigDb = 0;
  char const *zOrigTab = 0;
  char const *zOrigCol = 0;
#endif











  if( NEVER(pExpr==0) || pNC->pSrcList==0 ) return 0;
  switch( pExpr->op ){
    case TK_AGG_COLUMN:
    case TK_COLUMN: {
      /* The expression is a column. Locate the table the column is being
      ** extracted from in NameContext.pSrcList. This table may be real
................................................................................

      assert( pTab && pExpr->pTab==pTab );
      if( pS ){
        /* The "table" is actually a sub-select or a view in the FROM clause
        ** of the SELECT statement. Return the declaration type and origin
        ** data for the result-set column of the sub-select.
        */
        if( iCol>=0 && ALWAYS(iCol<pS->pEList->nExpr) ){
          /* If iCol is less than zero, then the expression requests the
          ** rowid of the sub-select or view. This expression is legal (see 
          ** test case misc2.2.2) - it always evaluates to NULL.
          **
          ** The ALWAYS() is because iCol>=pS->pEList->nExpr will have been
          ** caught already by name resolution.
          */
          NameContext sNC;
          Expr *p = pS->pEList->a[iCol].pExpr;
          sNC.pSrcList = pS->pSrc;
          sNC.pNext = pNC;
          sNC.pParse = pNC->pParse;
          zType = columnType(&sNC, p,&zOrigDb,&zOrigTab,&zOrigCol, &estWidth); 
................................................................................
  if( db->mallocFailed ) return;
  memset(&sNC, 0, sizeof(sNC));
  sNC.pSrcList = pSelect->pSrc;
  a = pSelect->pEList->a;
  for(i=0, pCol=pTab->aCol; i<pTab->nCol; i++, pCol++){
    p = a[i].pExpr;
    if( pCol->zType==0 ){
      pCol->zType = sqlite3DbStrDup(db, 
                        columnType(&sNC, p,0,0,0, &pCol->szEst));
    }
    szAll += pCol->szEst;
    pCol->affinity = sqlite3ExprAffinity(p);
    if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_BLOB;
    pColl = sqlite3ExprCollSeq(pParse, p);
    if( pColl && pCol->zColl==0 ){
      pCol->zColl = sqlite3DbStrDup(db, pColl->zName);
    }
  }
  pTab->szTabRow = sqlite3LogEst(szAll*4);
}
................................................................................
  CollSeq *pRet;
  if( p->pPrior ){
    pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
  }else{
    pRet = 0;
  }
  assert( iCol>=0 );
  /* iCol must be less than p->pEList->nExpr.  Otherwise an error would
  ** have been thrown during name resolution and we would not have gotten
  ** this far */
  if( pRet==0 && ALWAYS(iCol<p->pEList->nExpr) ){
    pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
  }
  return pRet;
}

/*
** The select statement passed as the second parameter is a compound SELECT
................................................................................
  SelectDest *pDest     /* What to do with query results */
);

/*
** Error message for when two or more terms of a compound select have different
** size result sets.
*/
SQLITE_PRIVATE void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p){
  if( p->selFlags & SF_Values ){
    sqlite3ErrorMsg(pParse, "all VALUES must have the same number of terms");
  }else{
    sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
      " do not have the same number of result columns", selectOpName(p->op));
  }
}
................................................................................
*/
static int multiSelectValues(
  Parse *pParse,        /* Parsing context */
  Select *p,            /* The right-most of SELECTs to be coded */
  SelectDest *pDest     /* What to do with query results */
){
  Select *pPrior;

  int nRow = 1;
  int rc = 0;
  assert( p->selFlags & SF_MultiValue );
  do{
    assert( p->selFlags & SF_Values );
    assert( p->op==TK_ALL || (p->op==TK_SELECT && p->pPrior==0) );
    assert( p->pLimit==0 );
    assert( p->pOffset==0 );
    assert( p->pNext==0 || p->pEList->nExpr==p->pNext->pEList->nExpr );



    if( p->pPrior==0 ) break;
    assert( p->pPrior->pNext==p );
    p = p->pPrior;
    nRow++;
  }while(1);
  while( p ){
    pPrior = p->pPrior;
................................................................................
    goto multi_select_end;
  }

  /* Make sure all SELECTs in the statement have the same number of elements
  ** in their result sets.
  */
  assert( p->pEList && pPrior->pEList );
  assert( p->pEList->nExpr==pPrior->pEList->nExpr );





#ifndef SQLITE_OMIT_CTE
  if( p->selFlags & SF_Recursive ){
    generateWithRecursiveQuery(pParse, p, &dest);
  }else
#endif

................................................................................
  ** collation.
  */
  aPermute = sqlite3DbMallocRaw(db, sizeof(int)*nOrderBy);
  if( aPermute ){
    struct ExprList_item *pItem;
    for(i=0, pItem=pOrderBy->a; i<nOrderBy; i++, pItem++){
      assert( pItem->u.x.iOrderByCol>0 );
      assert( pItem->u.x.iOrderByCol<=p->pEList->nExpr );


      aPermute[i] = pItem->u.x.iOrderByCol - 1;
    }
    pKeyMerge = multiSelectOrderByKeyInfo(pParse, p, 1);
  }else{
    pKeyMerge = 0;
  }

................................................................................
**   (8)  The subquery does not use LIMIT or the outer query is not a join.
**
**   (9)  The subquery does not use LIMIT or the outer query does not use
**        aggregates.
**
**  (**)  Restriction (10) was removed from the code on 2005-02-05 but we
**        accidently carried the comment forward until 2014-09-15.  Original
**        text: "The subquery does not use aggregates or the outer query 
**        does not use LIMIT."
**
**  (11)  The subquery and the outer query do not both have ORDER BY clauses.
**
**  (**)  Not implemented.  Subsumed into restriction (3).  Was previously
**        a separate restriction deriving from ticket #350.
**
**  (13)  The subquery and outer query do not both use LIMIT.
................................................................................
    if( isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){
      return 0;
    }
    for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
      testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
      testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
      assert( pSub->pSrc!=0 );
      assert( pSub->pEList->nExpr==pSub1->pEList->nExpr );
      if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0
       || (pSub1->pPrior && pSub1->op!=TK_ALL) 
       || pSub1->pSrc->nSrc<1

      ){
        return 0;
      }
      testcase( pSub1->pSrc->nSrc>1 );
    }

    /* Restriction 18. */
................................................................................
  /* Finially, delete what is left of the subquery and return
  ** success.
  */
  sqlite3SelectDelete(db, pSub1);

#if SELECTTRACE_ENABLED
  if( sqlite3SelectTrace & 0x100 ){
    SELECTTRACE(0x100,pParse,p,("After flattening:\n"));
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif

  return 1;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */



#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** Make copies of relevant WHERE clause terms of the outer query into
** the WHERE clause of subquery.  Example:
**
**    SELECT * FROM (SELECT a AS x, c-d AS y FROM t1) WHERE x=5 AND y=10;
**
** Transformed into:
**
**    SELECT * FROM (SELECT a AS x, c-d AS y FROM t1 WHERE a=5 AND c-d=10)
**     WHERE x=5 AND y=10;
**
** The hope is that the terms added to the inner query will make it more
** efficient.
**
** Do not attempt this optimization if:
**
**   (1) The inner query is an aggregate.  (In that case, we'd really want
**       to copy the outer WHERE-clause terms onto the HAVING clause of the
**       inner query.  But they probably won't help there so do not bother.)
**
**   (2) The inner query is the recursive part of a common table expression.
**
**   (3) The inner query has a LIMIT clause (since the changes to the WHERE
**       close would change the meaning of the LIMIT).
**
**   (4) The inner query is the right operand of a LEFT JOIN.  (The caller
**       enforces this restriction since this routine does not have enough
**       information to know.)
**
** Return 0 if no changes are made and non-zero if one or more WHERE clause
** terms are duplicated into the subquery.
*/
static int pushDownWhereTerms(
  sqlite3 *db,          /* The database connection (for malloc()) */
  Select *pSubq,        /* The subquery whose WHERE clause is to be augmented */
  Expr *pWhere,         /* The WHERE clause of the outer query */
  int iCursor           /* Cursor number of the subquery */
){
  Expr *pNew;
  int nChng = 0;
  if( pWhere==0 ) return 0;
  if( (pSubq->selFlags & (SF_Aggregate|SF_Recursive))!=0 ){
     return 0; /* restrictions (1) and (2) */
  }
  if( pSubq->pLimit!=0 ){
     return 0; /* restriction (3) */
  }
  while( pWhere->op==TK_AND ){
    nChng += pushDownWhereTerms(db, pSubq, pWhere->pRight, iCursor);
    pWhere = pWhere->pLeft;
  }
  if( sqlite3ExprIsTableConstant(pWhere, iCursor) ){
    nChng++;
    while( pSubq ){
      pNew = sqlite3ExprDup(db, pWhere, 0);
      pNew = substExpr(db, pNew, iCursor, pSubq->pEList);
      pSubq->pWhere = sqlite3ExprAnd(db, pSubq->pWhere, pNew);
      pSubq = pSubq->pPrior;
    }
  }
  return nChng;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */

/*
** Based on the contents of the AggInfo structure indicated by the first
** argument, this function checks if the following are true:
**
................................................................................
** If the source-list item passed as an argument was augmented with an
** INDEXED BY clause, then try to locate the specified index. If there
** was such a clause and the named index cannot be found, return 
** SQLITE_ERROR and leave an error in pParse. Otherwise, populate 
** pFrom->pIndex and return SQLITE_OK.
*/
SQLITE_PRIVATE int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){
  if( pFrom->pTab && pFrom->zIndexedBy ){
    Table *pTab = pFrom->pTab;
    char *zIndexedBy = pFrom->zIndexedBy;
    Index *pIdx;
    for(pIdx=pTab->pIndex; 
        pIdx && sqlite3StrICmp(pIdx->zName, zIndexedBy); 
        pIdx=pIdx->pNext
    );
    if( !pIdx ){
      sqlite3ErrorMsg(pParse, "no such index: %s", zIndexedBy, 0);
      pParse->checkSchema = 1;
      return SQLITE_ERROR;
    }
    pFrom->pIndex = pIdx;
  }
  return SQLITE_OK;
}
................................................................................
    p->pOrderBy = 0;
    p->selFlags &= ~SF_Distinct;
  }
  sqlite3SelectPrep(pParse, p, 0);
  memset(&sSort, 0, sizeof(sSort));
  sSort.pOrderBy = p->pOrderBy;
  pTabList = p->pSrc;

  if( pParse->nErr || db->mallocFailed ){
    goto select_end;
  }
  assert( p->pEList!=0 );
  isAgg = (p->selFlags & SF_Aggregate)!=0;

#if SELECTTRACE_ENABLED
  if( sqlite3SelectTrace & 0x100 ){
    SELECTTRACE(0x100,pParse,p, ("after name resolution:\n"));
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif







  /* If writing to memory or generating a set
  ** only a single column may be output.
  */
#ifndef SQLITE_OMIT_SUBQUERY
  if( checkForMultiColumnSelectError(pParse, pDest, p->pEList->nExpr) ){
    goto select_end;
  }
#endif

  /* Try to flatten subqueries in the FROM clause up into the main query
  */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
  for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
    struct SrcList_item *pItem = &pTabList->a[i];
    Select *pSub = pItem->pSelect;
    int isAggSub;
    if( pSub==0 ) continue;
    isAggSub = (pSub->selFlags & SF_Aggregate)!=0;
    if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){
      /* This subquery can be absorbed into its parent. */
      if( isAggSub ){
        isAgg = 1;
        p->selFlags |= SF_Aggregate;
      }
      i = -1;
    }
    pTabList = p->pSrc;
    if( db->mallocFailed ) goto select_end;
    if( !IgnorableOrderby(pDest) ){
      sSort.pOrderBy = p->pOrderBy;
    }
  }
#endif

  /* Get a pointer the VDBE under construction, allocating a new VDBE if one
  ** does not already exist */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto select_end;

#ifndef SQLITE_OMIT_COMPOUND_SELECT
  /* Handle compound SELECT statements using the separate multiSelect()
  ** procedure.
  */
  if( p->pPrior ){
    rc = multiSelect(pParse, p, pDest);
    explainSetInteger(pParse->iSelectId, iRestoreSelectId);
#if SELECTTRACE_ENABLED
    SELECTTRACE(1,pParse,p,("end compound-select processing\n"));
    pParse->nSelectIndent--;
#endif
    return rc;
  }
#endif

  /* Generate code for all sub-queries in the FROM clause
  */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
  for(i=0; i<pTabList->nSrc; i++){
    struct SrcList_item *pItem = &pTabList->a[i];
    SelectDest dest;
    Select *pSub = pItem->pSelect;


    if( pSub==0 ) continue;

    /* Sometimes the code for a subquery will be generated more than
    ** once, if the subquery is part of the WHERE clause in a LEFT JOIN,
    ** for example.  In that case, do not regenerate the code to manifest
    ** a view or the co-routine to implement a view.  The first instance
    ** is sufficient, though the subroutine to manifest the view does need
................................................................................
    ** may contain expression trees of at most
    ** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
    ** more conservative than necessary, but much easier than enforcing
    ** an exact limit.
    */
    pParse->nHeight += sqlite3SelectExprHeight(p);

    /* Make copies of constant WHERE-clause terms in the outer query down
    ** inside the subquery.  This can help the subquery to run more efficiently.
    */
    if( (pItem->jointype & JT_OUTER)==0
     && pushDownWhereTerms(db, pSub, p->pWhere, pItem->iCursor)

    ){
#if SELECTTRACE_ENABLED
      if( sqlite3SelectTrace & 0x100 ){
        SELECTTRACE(0x100,pParse,p,("After WHERE-clause push-down:\n"));
        sqlite3TreeViewSelect(0, p, 0);
      }

#endif
    }

    /* Generate code to implement the subquery
    */
    if( pTabList->nSrc==1
     && (p->selFlags & SF_All)==0
     && OptimizationEnabled(db, SQLITE_SubqCoroutine)
    ){
      /* Implement a co-routine that will return a single row of the result
      ** set on each invocation.
      */
      int addrTop = sqlite3VdbeCurrentAddr(v)+1;
      pItem->regReturn = ++pParse->nMem;
      sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
................................................................................
      pItem->pTab->nRowLogEst = sqlite3LogEst(pSub->nSelectRow);
      if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
      retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
      VdbeComment((v, "end %s", pItem->pTab->zName));
      sqlite3VdbeChangeP1(v, topAddr, retAddr);
      sqlite3ClearTempRegCache(pParse);
    }

    if( db->mallocFailed ) goto select_end;

    pParse->nHeight -= sqlite3SelectExprHeight(p);



  }
#endif

  /* Various elements of the SELECT copied into local variables for
  ** convenience */
  pEList = p->pEList;

  pWhere = p->pWhere;
  pGroupBy = p->pGroupBy;
  pHaving = p->pHaving;
  sDistinct.isTnct = (p->selFlags & SF_Distinct)!=0;







#if SELECTTRACE_ENABLED




  if( sqlite3SelectTrace & 0x400 ){
    SELECTTRACE(0x400,pParse,p,("After all FROM-clause analysis:\n"));
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif

  /* If the query is DISTINCT with an ORDER BY but is not an aggregate, and 
  ** if the select-list is the same as the ORDER BY list, then this query
  ** can be rewritten as a GROUP BY. In other words, this:
  **
................................................................................
  **
  ** The second form is preferred as a single index (or temp-table) may be 
  ** used for both the ORDER BY and DISTINCT processing. As originally 
  ** written the query must use a temp-table for at least one of the ORDER 
  ** BY and DISTINCT, and an index or separate temp-table for the other.
  */
  if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct 
   && sqlite3ExprListCompare(sSort.pOrderBy, pEList, -1)==0
  ){
    p->selFlags &= ~SF_Distinct;
    pGroupBy = p->pGroupBy = sqlite3ExprListDup(db, pEList, 0);

    /* Notice that even thought SF_Distinct has been cleared from p->selFlags,
    ** the sDistinct.isTnct is still set.  Hence, isTnct represents the
    ** original setting of the SF_Distinct flag, not the current setting */
    assert( sDistinct.isTnct );
  }

  /* If there is an ORDER BY clause, then create an ephemeral index to
  ** do the sorting.  But this sorting ephemeral index might end up
  ** being unused if the data can be extracted in pre-sorted order.
  ** If that is the case, then the OP_OpenEphemeral instruction will be
  ** changed to an OP_Noop once we figure out that the sorting index is
  ** not needed.  The sSort.addrSortIndex variable is used to facilitate
  ** that change.
  */
  if( sSort.pOrderBy ){
    KeyInfo *pKeyInfo;
    pKeyInfo = keyInfoFromExprList(pParse, sSort.pOrderBy, 0, pEList->nExpr);
    sSort.iECursor = pParse->nTab++;
    sSort.addrSortIndex =
      sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
................................................................................
  p->nSelectRow = LARGEST_INT64;
  computeLimitRegisters(pParse, p, iEnd);
  if( p->iLimit==0 && sSort.addrSortIndex>=0 ){
    sqlite3VdbeGetOp(v, sSort.addrSortIndex)->opcode = OP_SorterOpen;
    sSort.sortFlags |= SORTFLAG_UseSorter;
  }

  /* Open an ephemeral index to use for the distinct set.
  */
  if( p->selFlags & SF_Distinct ){
    sDistinct.tabTnct = pParse->nTab++;
    sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
                             sDistinct.tabTnct, 0, 0,
                             (char*)keyInfoFromExprList(pParse, p->pEList,0,0),
                             P4_KEYINFO);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
    sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
  }else{
    sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
  }

  if( !isAgg && pGroupBy==0 ){
................................................................................
        pItem->u.x.iAlias = 0;
      }
      if( p->nSelectRow>100 ) p->nSelectRow = 100;
    }else{
      p->nSelectRow = 1;
    }


    /* If there is both a GROUP BY and an ORDER BY clause and they are
    ** identical, then it may be possible to disable the ORDER BY clause 
    ** on the grounds that the GROUP BY will cause elements to come out 
    ** in the correct order. It also may not - the GROUP BY might use a
    ** database index that causes rows to be grouped together as required
    ** but not actually sorted. Either way, record the fact that the
    ** ORDER BY and GROUP BY clauses are the same by setting the orderByGrp
    ** variable.  */
    if( sqlite3ExprListCompare(pGroupBy, sSort.pOrderBy, -1)==0 ){
      orderByGrp = 1;
    }
................................................................................
      ** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
      ** Then compare the current GROUP BY terms against the GROUP BY terms
      ** from the previous row currently stored in a0, a1, a2...
      */
      addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
      sqlite3ExprCacheClear(pParse);
      if( groupBySort ){
        sqlite3VdbeAddOp3(v, OP_SorterData, sAggInfo.sortingIdx,
                          sortOut, sortPTab);
      }
      for(j=0; j<pGroupBy->nExpr; j++){
        if( groupBySort ){
          sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j);
        }else{
          sAggInfo.directMode = 1;
          sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j);
................................................................................
      */
      addrSetAbort = sqlite3VdbeCurrentAddr(v);
      sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
      VdbeComment((v, "set abort flag"));
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      sqlite3VdbeResolveLabel(v, addrOutputRow);
      addrOutputRow = sqlite3VdbeCurrentAddr(v);
      sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
      VdbeCoverage(v);
      VdbeComment((v, "Groupby result generator entry point"));
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      finalizeAggFunctions(pParse, &sAggInfo);
      sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, p->pEList, -1, &sSort,
                      &sDistinct, pDest,
                      addrOutputRow+1, addrSetAbort);
................................................................................
    explainTempTable(pParse, "DISTINCT");
  }

  /* If there is an ORDER BY clause, then we need to sort the results
  ** and send them to the callback one by one.
  */
  if( sSort.pOrderBy ){
    explainTempTable(pParse,
                     sSort.nOBSat>0 ? "RIGHT PART OF ORDER BY":"ORDER BY");
    generateSortTail(pParse, p, &sSort, pEList->nExpr, pDest);
  }

  /* Jump here to skip this query
  */
  sqlite3VdbeResolveLabel(v, iEnd);

................................................................................
#if SELECTTRACE_ENABLED
  SELECTTRACE(1,pParse,p,("end processing\n"));
  pParse->nSelectIndent--;
#endif
  return rc;
}































































































/************** End of select.c **********************************************/
/************** Begin file table.c *******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

#endif /* SQLITE_OMIT_VIRTUALTABLE */

/************** End of vtab.c ************************************************/
/************** Begin file wherecode.c ***************************************/
/*
** 2015-06-06
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.
**
** This file was split off from where.c on 2015-06-06 in order to reduce the
** size of where.c and make it easier to edit.  This file contains the routines
** that actually generate the bulk of the WHERE loop code.  The original where.c
** file retains the code that does query planning and analysis.
*/
/************** Include whereInt.h in the middle of wherecode.c **************/
/************** Begin file whereInt.h ****************************************/
/*
** 2013-11-12
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
................................................................................
** a separate source file for easier editing.
*/

/*
** Trace output macros
*/
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
/***/ int sqlite3WhereTrace;
#endif
#if defined(SQLITE_DEBUG) \
    && (defined(SQLITE_TEST) || defined(SQLITE_ENABLE_WHERETRACE))
# define WHERETRACE(K,X)  if(sqlite3WhereTrace&(K)) sqlite3DebugPrintf X
# define WHERETRACE_ENABLED 1
#else
# define WHERETRACE(K,X)
................................................................................
*/
#define N_OR_COST 3
struct WhereOrSet {
  u16 n;                      /* Number of valid a[] entries */
  WhereOrCost a[N_OR_COST];   /* Set of best costs */
};





/*
** Each instance of this object holds a sequence of WhereLoop objects
** that implement some or all of a query plan.
**
** Think of each WhereLoop object as a node in a graph with arcs
** showing dependencies and costs for travelling between nodes.  (That is
** not a completely accurate description because WhereLoop costs are a
................................................................................
** no gaps.
*/
struct WhereMaskSet {
  int n;                        /* Number of assigned cursor values */
  int ix[BMS];                  /* Cursor assigned to each bit */
};

/*
** Initialize a WhereMaskSet object
*/
#define initMaskSet(P)  (P)->n=0

/*
** This object is a convenience wrapper holding all information needed
** to construct WhereLoop objects for a particular query.
*/
struct WhereLoopBuilder {
  WhereInfo *pWInfo;        /* Information about this WHERE */
  WhereClause *pWC;         /* WHERE clause terms */
................................................................................
  int iBreak;               /* Jump here to break out of the loop */
  int savedNQueryLoop;      /* pParse->nQueryLoop outside the WHERE loop */
  int aiCurOnePass[2];      /* OP_OpenWrite cursors for the ONEPASS opt */
  WhereMaskSet sMaskSet;    /* Map cursor numbers to bitmasks */
  WhereClause sWC;          /* Decomposition of the WHERE clause */
  WhereLevel a[1];          /* Information about each nest loop in WHERE */
};

/*
** Private interfaces - callable only by other where.c routines.
**
** where.c:
*/
SQLITE_PRIVATE Bitmask sqlite3WhereGetMask(WhereMaskSet*,int);
SQLITE_PRIVATE WhereTerm *sqlite3WhereFindTerm(
  WhereClause *pWC,     /* The WHERE clause to be searched */
  int iCur,             /* Cursor number of LHS */
  int iColumn,          /* Column number of LHS */
  Bitmask notReady,     /* RHS must not overlap with this mask */
  u32 op,               /* Mask of WO_xx values describing operator */
  Index *pIdx           /* Must be compatible with this index, if not NULL */
);

/* wherecode.c: */
#ifndef SQLITE_OMIT_EXPLAIN
SQLITE_PRIVATE int sqlite3WhereExplainOneScan(
  Parse *pParse,                  /* Parse context */
  SrcList *pTabList,              /* Table list this loop refers to */
  WhereLevel *pLevel,             /* Scan to write OP_Explain opcode for */
  int iLevel,                     /* Value for "level" column of output */
  int iFrom,                      /* Value for "from" column of output */
  u16 wctrlFlags                  /* Flags passed to sqlite3WhereBegin() */
);
#else
# define sqlite3WhereExplainOneScan(u,v,w,x,y,z) 0
#endif /* SQLITE_OMIT_EXPLAIN */
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
SQLITE_PRIVATE void sqlite3WhereAddScanStatus(
  Vdbe *v,                        /* Vdbe to add scanstatus entry to */
  SrcList *pSrclist,              /* FROM clause pLvl reads data from */
  WhereLevel *pLvl,               /* Level to add scanstatus() entry for */
  int addrExplain                 /* Address of OP_Explain (or 0) */
);
#else
# define sqlite3WhereAddScanStatus(a, b, c, d) ((void)d)
#endif
SQLITE_PRIVATE Bitmask sqlite3WhereCodeOneLoopStart(
  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
  int iLevel,          /* Which level of pWInfo->a[] should be coded */
  Bitmask notReady     /* Which tables are currently available */
);

/* whereexpr.c: */
SQLITE_PRIVATE void sqlite3WhereClauseInit(WhereClause*,WhereInfo*);
SQLITE_PRIVATE void sqlite3WhereClauseClear(WhereClause*);
SQLITE_PRIVATE void sqlite3WhereSplit(WhereClause*,Expr*,u8);
SQLITE_PRIVATE Bitmask sqlite3WhereExprUsage(WhereMaskSet*, Expr*);
SQLITE_PRIVATE Bitmask sqlite3WhereExprListUsage(WhereMaskSet*, ExprList*);
SQLITE_PRIVATE void sqlite3WhereExprAnalyze(SrcList*, WhereClause*);





/*
** Bitmasks for the operators on WhereTerm objects.  These are all
** operators that are of interest to the query planner.  An
** OR-ed combination of these values can be used when searching for
** particular WhereTerms within a WhereClause.
*/
................................................................................
#define WHERE_MULTI_OR     0x00002000  /* OR using multiple indices */
#define WHERE_AUTO_INDEX   0x00004000  /* Uses an ephemeral index */
#define WHERE_SKIPSCAN     0x00008000  /* Uses the skip-scan algorithm */
#define WHERE_UNQ_WANTED   0x00010000  /* WHERE_ONEROW would have been helpful*/
#define WHERE_PARTIALIDX   0x00020000  /* The automatic index is partial */

/************** End of whereInt.h ********************************************/
/************** Continuing where we left off in wherecode.c ******************/

#ifndef SQLITE_OMIT_EXPLAIN
/*
** This routine is a helper for explainIndexRange() below
**
** pStr holds the text of an expression that we are building up one term
** at a time.  This routine adds a new term to the end of the expression.
** Terms are separated by AND so add the "AND" text for second and subsequent
** terms only.
*/
static void explainAppendTerm(
  StrAccum *pStr,             /* The text expression being built */
  int iTerm,                  /* Index of this term.  First is zero */
  const char *zColumn,        /* Name of the column */
  const char *zOp             /* Name of the operator */
){
  if( iTerm ) sqlite3StrAccumAppend(pStr, " AND ", 5);
  sqlite3StrAccumAppendAll(pStr, zColumn);
  sqlite3StrAccumAppend(pStr, zOp, 1);
  sqlite3StrAccumAppend(pStr, "?", 1);
}

/*
** Argument pLevel describes a strategy for scanning table pTab. This 
** function appends text to pStr that describes the subset of table
** rows scanned by the strategy in the form of an SQL expression.
**
** For example, if the query:
**
**   SELECT * FROM t1 WHERE a=1 AND b>2;
**
** is run and there is an index on (a, b), then this function returns a
** string similar to:
**
**   "a=? AND b>?"
*/
static void explainIndexRange(StrAccum *pStr, WhereLoop *pLoop, Table *pTab){
  Index *pIndex = pLoop->u.btree.pIndex;
  u16 nEq = pLoop->u.btree.nEq;
  u16 nSkip = pLoop->nSkip;
  int i, j;
  Column *aCol = pTab->aCol;
  i16 *aiColumn = pIndex->aiColumn;

  if( nEq==0 && (pLoop->wsFlags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))==0 ) return;
  sqlite3StrAccumAppend(pStr, " (", 2);
  for(i=0; i<nEq; i++){
    char *z = aiColumn[i] < 0 ? "rowid" : aCol[aiColumn[i]].zName;
    if( i>=nSkip ){
      explainAppendTerm(pStr, i, z, "=");
    }else{
      if( i ) sqlite3StrAccumAppend(pStr, " AND ", 5);
      sqlite3XPrintf(pStr, 0, "ANY(%s)", z);
    }
  }

  j = i;
  if( pLoop->wsFlags&WHERE_BTM_LIMIT ){
    char *z = aiColumn[j] < 0 ? "rowid" : aCol[aiColumn[j]].zName;
    explainAppendTerm(pStr, i++, z, ">");
  }
  if( pLoop->wsFlags&WHERE_TOP_LIMIT ){
    char *z = aiColumn[j] < 0 ? "rowid" : aCol[aiColumn[j]].zName;
    explainAppendTerm(pStr, i, z, "<");
  }
  sqlite3StrAccumAppend(pStr, ")", 1);
}

/*
** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
** command, or if either SQLITE_DEBUG or SQLITE_ENABLE_STMT_SCANSTATUS was
** defined at compile-time. If it is not a no-op, a single OP_Explain opcode 
** is added to the output to describe the table scan strategy in pLevel.
**
** If an OP_Explain opcode is added to the VM, its address is returned.
** Otherwise, if no OP_Explain is coded, zero is returned.
*/
SQLITE_PRIVATE int sqlite3WhereExplainOneScan(
  Parse *pParse,                  /* Parse context */
  SrcList *pTabList,              /* Table list this loop refers to */
  WhereLevel *pLevel,             /* Scan to write OP_Explain opcode for */
  int iLevel,                     /* Value for "level" column of output */
  int iFrom,                      /* Value for "from" column of output */
  u16 wctrlFlags                  /* Flags passed to sqlite3WhereBegin() */
){
  int ret = 0;
#if !defined(SQLITE_DEBUG) && !defined(SQLITE_ENABLE_STMT_SCANSTATUS)
  if( pParse->explain==2 )
#endif
  {
    struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
    Vdbe *v = pParse->pVdbe;      /* VM being constructed */
    sqlite3 *db = pParse->db;     /* Database handle */
    int iId = pParse->iSelectId;  /* Select id (left-most output column) */
    int isSearch;                 /* True for a SEARCH. False for SCAN. */
    WhereLoop *pLoop;             /* The controlling WhereLoop object */
    u32 flags;                    /* Flags that describe this loop */
    char *zMsg;                   /* Text to add to EQP output */
    StrAccum str;                 /* EQP output string */
    char zBuf[100];               /* Initial space for EQP output string */

    pLoop = pLevel->pWLoop;
    flags = pLoop->wsFlags;
    if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_ONETABLE_ONLY) ) return 0;

    isSearch = (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0
            || ((flags&WHERE_VIRTUALTABLE)==0 && (pLoop->u.btree.nEq>0))
            || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX));

    sqlite3StrAccumInit(&str, db, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
    sqlite3StrAccumAppendAll(&str, isSearch ? "SEARCH" : "SCAN");
    if( pItem->pSelect ){
      sqlite3XPrintf(&str, 0, " SUBQUERY %d", pItem->iSelectId);
    }else{
      sqlite3XPrintf(&str, 0, " TABLE %s", pItem->zName);
    }

    if( pItem->zAlias ){
      sqlite3XPrintf(&str, 0, " AS %s", pItem->zAlias);
    }
    if( (flags & (WHERE_IPK|WHERE_VIRTUALTABLE))==0 ){
      const char *zFmt = 0;
      Index *pIdx;

      assert( pLoop->u.btree.pIndex!=0 );
      pIdx = pLoop->u.btree.pIndex;
      assert( !(flags&WHERE_AUTO_INDEX) || (flags&WHERE_IDX_ONLY) );
      if( !HasRowid(pItem->pTab) && IsPrimaryKeyIndex(pIdx) ){
        if( isSearch ){
          zFmt = "PRIMARY KEY";
        }
      }else if( flags & WHERE_PARTIALIDX ){
        zFmt = "AUTOMATIC PARTIAL COVERING INDEX";
      }else if( flags & WHERE_AUTO_INDEX ){
        zFmt = "AUTOMATIC COVERING INDEX";
      }else if( flags & WHERE_IDX_ONLY ){
        zFmt = "COVERING INDEX %s";
      }else{
        zFmt = "INDEX %s";
      }
      if( zFmt ){
        sqlite3StrAccumAppend(&str, " USING ", 7);
        sqlite3XPrintf(&str, 0, zFmt, pIdx->zName);
        explainIndexRange(&str, pLoop, pItem->pTab);
      }
    }else if( (flags & WHERE_IPK)!=0 && (flags & WHERE_CONSTRAINT)!=0 ){
      const char *zRange;
      if( flags&(WHERE_COLUMN_EQ|WHERE_COLUMN_IN) ){
        zRange = "(rowid=?)";
      }else if( (flags&WHERE_BOTH_LIMIT)==WHERE_BOTH_LIMIT ){
        zRange = "(rowid>? AND rowid<?)";
      }else if( flags&WHERE_BTM_LIMIT ){
        zRange = "(rowid>?)";
      }else{
        assert( flags&WHERE_TOP_LIMIT);
        zRange = "(rowid<?)";
      }
      sqlite3StrAccumAppendAll(&str, " USING INTEGER PRIMARY KEY ");
      sqlite3StrAccumAppendAll(&str, zRange);
    }
#ifndef SQLITE_OMIT_VIRTUALTABLE
    else if( (flags & WHERE_VIRTUALTABLE)!=0 ){
      sqlite3XPrintf(&str, 0, " VIRTUAL TABLE INDEX %d:%s",
                  pLoop->u.vtab.idxNum, pLoop->u.vtab.idxStr);
    }
#endif
#ifdef SQLITE_EXPLAIN_ESTIMATED_ROWS
    if( pLoop->nOut>=10 ){
      sqlite3XPrintf(&str, 0, " (~%llu rows)", sqlite3LogEstToInt(pLoop->nOut));
    }else{
      sqlite3StrAccumAppend(&str, " (~1 row)", 9);
    }
#endif
    zMsg = sqlite3StrAccumFinish(&str);
    ret = sqlite3VdbeAddOp4(v, OP_Explain, iId, iLevel, iFrom, zMsg,P4_DYNAMIC);
  }
  return ret;
}
#endif /* SQLITE_OMIT_EXPLAIN */

#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
/*
** Configure the VM passed as the first argument with an
** sqlite3_stmt_scanstatus() entry corresponding to the scan used to 
** implement level pLvl. Argument pSrclist is a pointer to the FROM 
** clause that the scan reads data from.
**
** If argument addrExplain is not 0, it must be the address of an 
** OP_Explain instruction that describes the same loop.
*/
SQLITE_PRIVATE void sqlite3WhereAddScanStatus(
  Vdbe *v,                        /* Vdbe to add scanstatus entry to */
  SrcList *pSrclist,              /* FROM clause pLvl reads data from */
  WhereLevel *pLvl,               /* Level to add scanstatus() entry for */
  int addrExplain                 /* Address of OP_Explain (or 0) */
){
  const char *zObj = 0;
  WhereLoop *pLoop = pLvl->pWLoop;
  if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0  &&  pLoop->u.btree.pIndex!=0 ){
    zObj = pLoop->u.btree.pIndex->zName;
  }else{
    zObj = pSrclist->a[pLvl->iFrom].zName;
  }
  sqlite3VdbeScanStatus(
      v, addrExplain, pLvl->addrBody, pLvl->addrVisit, pLoop->nOut, zObj
  );
}
#endif


/*
** Disable a term in the WHERE clause.  Except, do not disable the term
** if it controls a LEFT OUTER JOIN and it did not originate in the ON
** or USING clause of that join.
**
** Consider the term t2.z='ok' in the following queries:
**
**   (1)  SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok'
**   (2)  SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok'
**   (3)  SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok'
**
** The t2.z='ok' is disabled in the in (2) because it originates
** in the ON clause.  The term is disabled in (3) because it is not part
** of a LEFT OUTER JOIN.  In (1), the term is not disabled.
**
** Disabling a term causes that term to not be tested in the inner loop
** of the join.  Disabling is an optimization.  When terms are satisfied
** by indices, we disable them to prevent redundant tests in the inner
** loop.  We would get the correct results if nothing were ever disabled,
** but joins might run a little slower.  The trick is to disable as much
** as we can without disabling too much.  If we disabled in (1), we'd get
** the wrong answer.  See ticket #813.
**
** If all the children of a term are disabled, then that term is also
** automatically disabled.  In this way, terms get disabled if derived
** virtual terms are tested first.  For example:
**
**      x GLOB 'abc*' AND x>='abc' AND x<'acd'
**      \___________/     \______/     \_____/
**         parent          child1       child2
**
** Only the parent term was in the original WHERE clause.  The child1
** and child2 terms were added by the LIKE optimization.  If both of
** the virtual child terms are valid, then testing of the parent can be 
** skipped.
**
** Usually the parent term is marked as TERM_CODED.  But if the parent
** term was originally TERM_LIKE, then the parent gets TERM_LIKECOND instead.
** The TERM_LIKECOND marking indicates that the term should be coded inside
** a conditional such that is only evaluated on the second pass of a
** LIKE-optimization loop, when scanning BLOBs instead of strings.
*/
static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
  int nLoop = 0;
  while( pTerm
      && (pTerm->wtFlags & TERM_CODED)==0
      && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
      && (pLevel->notReady & pTerm->prereqAll)==0
  ){
    if( nLoop && (pTerm->wtFlags & TERM_LIKE)!=0 ){
      pTerm->wtFlags |= TERM_LIKECOND;
    }else{
      pTerm->wtFlags |= TERM_CODED;
    }
    if( pTerm->iParent<0 ) break;
    pTerm = &pTerm->pWC->a[pTerm->iParent];
    pTerm->nChild--;
    if( pTerm->nChild!=0 ) break;
    nLoop++;
  }
}

/*
** Code an OP_Affinity opcode to apply the column affinity string zAff
** to the n registers starting at base. 
**
** As an optimization, SQLITE_AFF_BLOB entries (which are no-ops) at the
** beginning and end of zAff are ignored.  If all entries in zAff are
** SQLITE_AFF_BLOB, then no code gets generated.
**
** This routine makes its own copy of zAff so that the caller is free
** to modify zAff after this routine returns.
*/
static void codeApplyAffinity(Parse *pParse, int base, int n, char *zAff){
  Vdbe *v = pParse->pVdbe;
  if( zAff==0 ){
    assert( pParse->db->mallocFailed );
    return;
  }
  assert( v!=0 );

  /* Adjust base and n to skip over SQLITE_AFF_BLOB entries at the beginning
  ** and end of the affinity string.
  */
  while( n>0 && zAff[0]==SQLITE_AFF_BLOB ){
    n--;
    base++;
    zAff++;
  }
  while( n>1 && zAff[n-1]==SQLITE_AFF_BLOB ){
    n--;
  }

  /* Code the OP_Affinity opcode if there is anything left to do. */
  if( n>0 ){
    sqlite3VdbeAddOp2(v, OP_Affinity, base, n);
    sqlite3VdbeChangeP4(v, -1, zAff, n);
    sqlite3ExprCacheAffinityChange(pParse, base, n);
  }
}


/*
** Generate code for a single equality term of the WHERE clause.  An equality
** term can be either X=expr or X IN (...).   pTerm is the term to be 
** coded.
**
** The current value for the constraint is left in register iReg.
**
** For a constraint of the form X=expr, the expression is evaluated and its
** result is left on the stack.  For constraints of the form X IN (...)
** this routine sets up a loop that will iterate over all values of X.
*/
static int codeEqualityTerm(
  Parse *pParse,      /* The parsing context */
  WhereTerm *pTerm,   /* The term of the WHERE clause to be coded */
  WhereLevel *pLevel, /* The level of the FROM clause we are working on */
  int iEq,            /* Index of the equality term within this level */
  int bRev,           /* True for reverse-order IN operations */
  int iTarget         /* Attempt to leave results in this register */
){
  Expr *pX = pTerm->pExpr;
  Vdbe *v = pParse->pVdbe;
  int iReg;                  /* Register holding results */

  assert( iTarget>0 );
  if( pX->op==TK_EQ || pX->op==TK_IS ){
    iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);
  }else if( pX->op==TK_ISNULL ){
    iReg = iTarget;
    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
#ifndef SQLITE_OMIT_SUBQUERY
  }else{
    int eType;
    int iTab;
    struct InLoop *pIn;
    WhereLoop *pLoop = pLevel->pWLoop;

    if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0
      && pLoop->u.btree.pIndex!=0
      && pLoop->u.btree.pIndex->aSortOrder[iEq]
    ){
      testcase( iEq==0 );
      testcase( bRev );
      bRev = !bRev;
    }
    assert( pX->op==TK_IN );
    iReg = iTarget;
    eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0);
    if( eType==IN_INDEX_INDEX_DESC ){
      testcase( bRev );
      bRev = !bRev;
    }
    iTab = pX->iTable;
    sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iTab, 0);
    VdbeCoverageIf(v, bRev);
    VdbeCoverageIf(v, !bRev);
    assert( (pLoop->wsFlags & WHERE_MULTI_OR)==0 );
    pLoop->wsFlags |= WHERE_IN_ABLE;
    if( pLevel->u.in.nIn==0 ){
      pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
    }
    pLevel->u.in.nIn++;
    pLevel->u.in.aInLoop =
       sqlite3DbReallocOrFree(pParse->db, pLevel->u.in.aInLoop,
                              sizeof(pLevel->u.in.aInLoop[0])*pLevel->u.in.nIn);
    pIn = pLevel->u.in.aInLoop;
    if( pIn ){
      pIn += pLevel->u.in.nIn - 1;
      pIn->iCur = iTab;
      if( eType==IN_INDEX_ROWID ){
        pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iReg);
      }else{
        pIn->addrInTop = sqlite3VdbeAddOp3(v, OP_Column, iTab, 0, iReg);
      }
      pIn->eEndLoopOp = bRev ? OP_PrevIfOpen : OP_NextIfOpen;
      sqlite3VdbeAddOp1(v, OP_IsNull, iReg); VdbeCoverage(v);
    }else{
      pLevel->u.in.nIn = 0;
    }
#endif
  }
  disableTerm(pLevel, pTerm);
  return iReg;
}

/*
** Generate code that will evaluate all == and IN constraints for an
** index scan.
**
** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c).
** Suppose the WHERE clause is this:  a==5 AND b IN (1,2,3) AND c>5 AND c<10
** The index has as many as three equality constraints, but in this
** example, the third "c" value is an inequality.  So only two 
** constraints are coded.  This routine will generate code to evaluate
** a==5 and b IN (1,2,3).  The current values for a and b will be stored
** in consecutive registers and the index of the first register is returned.
**
** In the example above nEq==2.  But this subroutine works for any value
** of nEq including 0.  If nEq==0, this routine is nearly a no-op.
** The only thing it does is allocate the pLevel->iMem memory cell and
** compute the affinity string.
**
** The nExtraReg parameter is 0 or 1.  It is 0 if all WHERE clause constraints
** are == or IN and are covered by the nEq.  nExtraReg is 1 if there is
** an inequality constraint (such as the "c>=5 AND c<10" in the example) that
** occurs after the nEq quality constraints.
**
** This routine allocates a range of nEq+nExtraReg memory cells and returns
** the index of the first memory cell in that range. The code that
** calls this routine will use that memory range to store keys for
** start and termination conditions of the loop.
** key value of the loop.  If one or more IN operators appear, then
** this routine allocates an additional nEq memory cells for internal
** use.
**
** Before returning, *pzAff is set to point to a buffer containing a
** copy of the column affinity string of the index allocated using
** sqlite3DbMalloc(). Except, entries in the copy of the string associated
** with equality constraints that use BLOB or NONE affinity are set to
** SQLITE_AFF_BLOB. This is to deal with SQL such as the following:
**
**   CREATE TABLE t1(a TEXT PRIMARY KEY, b);
**   SELECT ... FROM t1 AS t2, t1 WHERE t1.a = t2.b;
**
** In the example above, the index on t1(a) has TEXT affinity. But since
** the right hand side of the equality constraint (t2.b) has BLOB/NONE affinity,
** no conversion should be attempted before using a t2.b value as part of
** a key to search the index. Hence the first byte in the returned affinity
** string in this example would be set to SQLITE_AFF_BLOB.
*/
static int codeAllEqualityTerms(
  Parse *pParse,        /* Parsing context */
  WhereLevel *pLevel,   /* Which nested loop of the FROM we are coding */
  int bRev,             /* Reverse the order of IN operators */
  int nExtraReg,        /* Number of extra registers to allocate */
  char **pzAff          /* OUT: Set to point to affinity string */
){
  u16 nEq;                      /* The number of == or IN constraints to code */
  u16 nSkip;                    /* Number of left-most columns to skip */
  Vdbe *v = pParse->pVdbe;      /* The vm under construction */
  Index *pIdx;                  /* The index being used for this loop */
  WhereTerm *pTerm;             /* A single constraint term */
  WhereLoop *pLoop;             /* The WhereLoop object */
  int j;                        /* Loop counter */
  int regBase;                  /* Base register */
  int nReg;                     /* Number of registers to allocate */
  char *zAff;                   /* Affinity string to return */

  /* This module is only called on query plans that use an index. */
  pLoop = pLevel->pWLoop;
  assert( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 );
  nEq = pLoop->u.btree.nEq;
  nSkip = pLoop->nSkip;
  pIdx = pLoop->u.btree.pIndex;
  assert( pIdx!=0 );

  /* Figure out how many memory cells we will need then allocate them.
  */
  regBase = pParse->nMem + 1;
  nReg = pLoop->u.btree.nEq + nExtraReg;
  pParse->nMem += nReg;

  zAff = sqlite3DbStrDup(pParse->db, sqlite3IndexAffinityStr(v, pIdx));
  if( !zAff ){
    pParse->db->mallocFailed = 1;
  }

  if( nSkip ){
    int iIdxCur = pLevel->iIdxCur;
    sqlite3VdbeAddOp1(v, (bRev?OP_Last:OP_Rewind), iIdxCur);
    VdbeCoverageIf(v, bRev==0);
    VdbeCoverageIf(v, bRev!=0);
    VdbeComment((v, "begin skip-scan on %s", pIdx->zName));
    j = sqlite3VdbeAddOp0(v, OP_Goto);
    pLevel->addrSkip = sqlite3VdbeAddOp4Int(v, (bRev?OP_SeekLT:OP_SeekGT),
                            iIdxCur, 0, regBase, nSkip);
    VdbeCoverageIf(v, bRev==0);
    VdbeCoverageIf(v, bRev!=0);
    sqlite3VdbeJumpHere(v, j);
    for(j=0; j<nSkip; j++){
      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, j, regBase+j);
      assert( pIdx->aiColumn[j]>=0 );
      VdbeComment((v, "%s", pIdx->pTable->aCol[pIdx->aiColumn[j]].zName));
    }
  }    

  /* Evaluate the equality constraints
  */
  assert( zAff==0 || (int)strlen(zAff)>=nEq );
  for(j=nSkip; j<nEq; j++){
    int r1;
    pTerm = pLoop->aLTerm[j];
    assert( pTerm!=0 );
    /* The following testcase is true for indices with redundant columns. 
    ** Ex: CREATE INDEX i1 ON t1(a,b,a); SELECT * FROM t1 WHERE a=0 AND b=0; */
    testcase( (pTerm->wtFlags & TERM_CODED)!=0 );
    testcase( pTerm->wtFlags & TERM_VIRTUAL );
    r1 = codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, regBase+j);
    if( r1!=regBase+j ){
      if( nReg==1 ){
        sqlite3ReleaseTempReg(pParse, regBase);
        regBase = r1;
      }else{
        sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
      }
    }
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_IN );
    if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
      Expr *pRight = pTerm->pExpr->pRight;
      if( (pTerm->wtFlags & TERM_IS)==0 && sqlite3ExprCanBeNull(pRight) ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
        VdbeCoverage(v);
      }
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_BLOB ){
          zAff[j] = SQLITE_AFF_BLOB;
        }
        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){
          zAff[j] = SQLITE_AFF_BLOB;
        }
      }
    }
  }
  *pzAff = zAff;
  return regBase;
}

/*
** If the most recently coded instruction is a constant range contraint
** that originated from the LIKE optimization, then change the P3 to be
** pLoop->iLikeRepCntr and set P5.
**
** The LIKE optimization trys to evaluate "x LIKE 'abc%'" as a range
** expression: "x>='ABC' AND x<'abd'".  But this requires that the range
** scan loop run twice, once for strings and a second time for BLOBs.
** The OP_String opcodes on the second pass convert the upper and lower
** bound string contants to blobs.  This routine makes the necessary changes
** to the OP_String opcodes for that to happen.
*/
static void whereLikeOptimizationStringFixup(
  Vdbe *v,                /* prepared statement under construction */
  WhereLevel *pLevel,     /* The loop that contains the LIKE operator */
  WhereTerm *pTerm        /* The upper or lower bound just coded */
){
  if( pTerm->wtFlags & TERM_LIKEOPT ){
    VdbeOp *pOp;
    assert( pLevel->iLikeRepCntr>0 );
    pOp = sqlite3VdbeGetOp(v, -1);
    assert( pOp!=0 );
    assert( pOp->opcode==OP_String8 
            || pTerm->pWC->pWInfo->pParse->db->mallocFailed );
    pOp->p3 = pLevel->iLikeRepCntr;
    pOp->p5 = 1;
  }
}


/*
** Generate code for the start of the iLevel-th loop in the WHERE clause
** implementation described by pWInfo.
*/
SQLITE_PRIVATE Bitmask sqlite3WhereCodeOneLoopStart(
  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
  int iLevel,          /* Which level of pWInfo->a[] should be coded */
  Bitmask notReady     /* Which tables are currently available */
){
  int j, k;            /* Loop counters */
  int iCur;            /* The VDBE cursor for the table */
  int addrNxt;         /* Where to jump to continue with the next IN case */
  int omitTable;       /* True if we use the index only */
  int bRev;            /* True if we need to scan in reverse order */
  WhereLevel *pLevel;  /* The where level to be coded */
  WhereLoop *pLoop;    /* The WhereLoop object being coded */
  WhereClause *pWC;    /* Decomposition of the entire WHERE clause */
  WhereTerm *pTerm;               /* A WHERE clause term */
  Parse *pParse;                  /* Parsing context */
  sqlite3 *db;                    /* Database connection */
  Vdbe *v;                        /* The prepared stmt under constructions */
  struct SrcList_item *pTabItem;  /* FROM clause term being coded */
  int addrBrk;                    /* Jump here to break out of the loop */
  int addrCont;                   /* Jump here to continue with next cycle */
  int iRowidReg = 0;        /* Rowid is stored in this register, if not zero */
  int iReleaseReg = 0;      /* Temp register to free before returning */

  pParse = pWInfo->pParse;
  v = pParse->pVdbe;
  pWC = &pWInfo->sWC;
  db = pParse->db;
  pLevel = &pWInfo->a[iLevel];
  pLoop = pLevel->pWLoop;
  pTabItem = &pWInfo->pTabList->a[pLevel->iFrom];
  iCur = pTabItem->iCursor;
  pLevel->notReady = notReady & ~sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur);
  bRev = (pWInfo->revMask>>iLevel)&1;
  omitTable = (pLoop->wsFlags & WHERE_IDX_ONLY)!=0 
           && (pWInfo->wctrlFlags & WHERE_FORCE_TABLE)==0;
  VdbeModuleComment((v, "Begin WHERE-loop%d: %s",iLevel,pTabItem->pTab->zName));

  /* Create labels for the "break" and "continue" instructions
  ** for the current loop.  Jump to addrBrk to break out of a loop.
  ** Jump to cont to go immediately to the next iteration of the
  ** loop.
  **
  ** When there is an IN operator, we also have a "addrNxt" label that
  ** means to continue with the next IN value combination.  When
  ** there are no IN operators in the constraints, the "addrNxt" label
  ** is the same as "addrBrk".
  */
  addrBrk = pLevel->addrBrk = pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
  addrCont = pLevel->addrCont = sqlite3VdbeMakeLabel(v);

  /* If this is the right table of a LEFT OUTER JOIN, allocate and
  ** initialize a memory cell that records if this table matches any
  ** row of the left table of the join.
  */
  if( pLevel->iFrom>0 && (pTabItem[0].jointype & JT_LEFT)!=0 ){
    pLevel->iLeftJoin = ++pParse->nMem;
    sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
    VdbeComment((v, "init LEFT JOIN no-match flag"));
  }

  /* Special case of a FROM clause subquery implemented as a co-routine */
  if( pTabItem->viaCoroutine ){
    int regYield = pTabItem->regReturn;
    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);
    pLevel->p2 =  sqlite3VdbeAddOp2(v, OP_Yield, regYield, addrBrk);
    VdbeCoverage(v);
    VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->zName));
    pLevel->op = OP_Goto;
  }else

#ifndef SQLITE_OMIT_VIRTUALTABLE
  if(  (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
    /* Case 1:  The table is a virtual-table.  Use the VFilter and VNext
    **          to access the data.
    */
    int iReg;   /* P3 Value for OP_VFilter */
    int addrNotFound;
    int nConstraint = pLoop->nLTerm;

    sqlite3ExprCachePush(pParse);
    iReg = sqlite3GetTempRange(pParse, nConstraint+2);
    addrNotFound = pLevel->addrBrk;
    for(j=0; j<nConstraint; j++){
      int iTarget = iReg+j+2;
      pTerm = pLoop->aLTerm[j];
      if( pTerm==0 ) continue;
      if( pTerm->eOperator & WO_IN ){
        codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, iTarget);
        addrNotFound = pLevel->addrNxt;
      }else{
        sqlite3ExprCode(pParse, pTerm->pExpr->pRight, iTarget);
      }
    }
    sqlite3VdbeAddOp2(v, OP_Integer, pLoop->u.vtab.idxNum, iReg);
    sqlite3VdbeAddOp2(v, OP_Integer, nConstraint, iReg+1);
    sqlite3VdbeAddOp4(v, OP_VFilter, iCur, addrNotFound, iReg,
                      pLoop->u.vtab.idxStr,
                      pLoop->u.vtab.needFree ? P4_MPRINTF : P4_STATIC);
    VdbeCoverage(v);
    pLoop->u.vtab.needFree = 0;
    for(j=0; j<nConstraint && j<16; j++){
      if( (pLoop->u.vtab.omitMask>>j)&1 ){
        disableTerm(pLevel, pLoop->aLTerm[j]);
      }
    }
    pLevel->op = OP_VNext;
    pLevel->p1 = iCur;
    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
    sqlite3ReleaseTempRange(pParse, iReg, nConstraint+2);
    sqlite3ExprCachePop(pParse);
  }else
#endif /* SQLITE_OMIT_VIRTUALTABLE */

  if( (pLoop->wsFlags & WHERE_IPK)!=0
   && (pLoop->wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_EQ))!=0
  ){
    /* Case 2:  We can directly reference a single row using an
    **          equality comparison against the ROWID field.  Or
    **          we reference multiple rows using a "rowid IN (...)"
    **          construct.
    */
    assert( pLoop->u.btree.nEq==1 );
    pTerm = pLoop->aLTerm[0];
    assert( pTerm!=0 );
    assert( pTerm->pExpr!=0 );
    assert( omitTable==0 );
    testcase( pTerm->wtFlags & TERM_VIRTUAL );
    iReleaseReg = ++pParse->nMem;
    iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, 0, bRev, iReleaseReg);
    if( iRowidReg!=iReleaseReg ) sqlite3ReleaseTempReg(pParse, iReleaseReg);
    addrNxt = pLevel->addrNxt;
    sqlite3VdbeAddOp2(v, OP_MustBeInt, iRowidReg, addrNxt); VdbeCoverage(v);
    sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addrNxt, iRowidReg);
    VdbeCoverage(v);
    sqlite3ExprCacheAffinityChange(pParse, iRowidReg, 1);
    sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
    VdbeComment((v, "pk"));
    pLevel->op = OP_Noop;
  }else if( (pLoop->wsFlags & WHERE_IPK)!=0
         && (pLoop->wsFlags & WHERE_COLUMN_RANGE)!=0
  ){
    /* Case 3:  We have an inequality comparison against the ROWID field.
    */
    int testOp = OP_Noop;
    int start;
    int memEndValue = 0;
    WhereTerm *pStart, *pEnd;

    assert( omitTable==0 );
    j = 0;
    pStart = pEnd = 0;
    if( pLoop->wsFlags & WHERE_BTM_LIMIT ) pStart = pLoop->aLTerm[j++];
    if( pLoop->wsFlags & WHERE_TOP_LIMIT ) pEnd = pLoop->aLTerm[j++];
    assert( pStart!=0 || pEnd!=0 );
    if( bRev ){
      pTerm = pStart;
      pStart = pEnd;
      pEnd = pTerm;
    }
    if( pStart ){
      Expr *pX;             /* The expression that defines the start bound */
      int r1, rTemp;        /* Registers for holding the start boundary */

      /* The following constant maps TK_xx codes into corresponding 
      ** seek opcodes.  It depends on a particular ordering of TK_xx
      */
      const u8 aMoveOp[] = {
           /* TK_GT */  OP_SeekGT,
           /* TK_LE */  OP_SeekLE,
           /* TK_LT */  OP_SeekLT,
           /* TK_GE */  OP_SeekGE
      };
      assert( TK_LE==TK_GT+1 );      /* Make sure the ordering.. */
      assert( TK_LT==TK_GT+2 );      /*  ... of the TK_xx values... */
      assert( TK_GE==TK_GT+3 );      /*  ... is correcct. */

      assert( (pStart->wtFlags & TERM_VNULL)==0 );
      testcase( pStart->wtFlags & TERM_VIRTUAL );
      pX = pStart->pExpr;
      assert( pX!=0 );
      testcase( pStart->leftCursor!=iCur ); /* transitive constraints */
      r1 = sqlite3ExprCodeTemp(pParse, pX->pRight, &rTemp);
      sqlite3VdbeAddOp3(v, aMoveOp[pX->op-TK_GT], iCur, addrBrk, r1);
      VdbeComment((v, "pk"));
      VdbeCoverageIf(v, pX->op==TK_GT);
      VdbeCoverageIf(v, pX->op==TK_LE);
      VdbeCoverageIf(v, pX->op==TK_LT);
      VdbeCoverageIf(v, pX->op==TK_GE);
      sqlite3ExprCacheAffinityChange(pParse, r1, 1);
      sqlite3ReleaseTempReg(pParse, rTemp);
      disableTerm(pLevel, pStart);
    }else{
      sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, addrBrk);
      VdbeCoverageIf(v, bRev==0);
      VdbeCoverageIf(v, bRev!=0);
    }
    if( pEnd ){
      Expr *pX;
      pX = pEnd->pExpr;
      assert( pX!=0 );
      assert( (pEnd->wtFlags & TERM_VNULL)==0 );
      testcase( pEnd->leftCursor!=iCur ); /* Transitive constraints */
      testcase( pEnd->wtFlags & TERM_VIRTUAL );
      memEndValue = ++pParse->nMem;
      sqlite3ExprCode(pParse, pX->pRight, memEndValue);
      if( pX->op==TK_LT || pX->op==TK_GT ){
        testOp = bRev ? OP_Le : OP_Ge;
      }else{
        testOp = bRev ? OP_Lt : OP_Gt;
      }
      disableTerm(pLevel, pEnd);
    }
    start = sqlite3VdbeCurrentAddr(v);
    pLevel->op = bRev ? OP_Prev : OP_Next;
    pLevel->p1 = iCur;
    pLevel->p2 = start;
    assert( pLevel->p5==0 );
    if( testOp!=OP_Noop ){
      iRowidReg = ++pParse->nMem;
      sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg);
      sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
      sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, iRowidReg);
      VdbeCoverageIf(v, testOp==OP_Le);
      VdbeCoverageIf(v, testOp==OP_Lt);
      VdbeCoverageIf(v, testOp==OP_Ge);
      VdbeCoverageIf(v, testOp==OP_Gt);
      sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL);
    }
  }else if( pLoop->wsFlags & WHERE_INDEXED ){
    /* Case 4: A scan using an index.
    **
    **         The WHERE clause may contain zero or more equality 
    **         terms ("==" or "IN" operators) that refer to the N
    **         left-most columns of the index. It may also contain
    **         inequality constraints (>, <, >= or <=) on the indexed
    **         column that immediately follows the N equalities. Only 
    **         the right-most column can be an inequality - the rest must
    **         use the "==" and "IN" operators. For example, if the 
    **         index is on (x,y,z), then the following clauses are all 
    **         optimized:
    **
    **            x=5
    **            x=5 AND y=10
    **            x=5 AND y<10
    **            x=5 AND y>5 AND y<10
    **            x=5 AND y=5 AND z<=10
    **
    **         The z<10 term of the following cannot be used, only
    **         the x=5 term:
    **
    **            x=5 AND z<10
    **
    **         N may be zero if there are inequality constraints.
    **         If there are no inequality constraints, then N is at
    **         least one.
    **
    **         This case is also used when there are no WHERE clause
    **         constraints but an index is selected anyway, in order
    **         to force the output order to conform to an ORDER BY.
    */  
    static const u8 aStartOp[] = {
      0,
      0,
      OP_Rewind,           /* 2: (!start_constraints && startEq &&  !bRev) */
      OP_Last,             /* 3: (!start_constraints && startEq &&   bRev) */
      OP_SeekGT,           /* 4: (start_constraints  && !startEq && !bRev) */
      OP_SeekLT,           /* 5: (start_constraints  && !startEq &&  bRev) */
      OP_SeekGE,           /* 6: (start_constraints  &&  startEq && !bRev) */
      OP_SeekLE            /* 7: (start_constraints  &&  startEq &&  bRev) */
    };
    static const u8 aEndOp[] = {
      OP_IdxGE,            /* 0: (end_constraints && !bRev && !endEq) */
      OP_IdxGT,            /* 1: (end_constraints && !bRev &&  endEq) */
      OP_IdxLE,            /* 2: (end_constraints &&  bRev && !endEq) */
      OP_IdxLT,            /* 3: (end_constraints &&  bRev &&  endEq) */
    };
    u16 nEq = pLoop->u.btree.nEq;     /* Number of == or IN terms */
    int regBase;                 /* Base register holding constraint values */
    WhereTerm *pRangeStart = 0;  /* Inequality constraint at range start */
    WhereTerm *pRangeEnd = 0;    /* Inequality constraint at range end */
    int startEq;                 /* True if range start uses ==, >= or <= */
    int endEq;                   /* True if range end uses ==, >= or <= */
    int start_constraints;       /* Start of range is constrained */
    int nConstraint;             /* Number of constraint terms */
    Index *pIdx;                 /* The index we will be using */
    int iIdxCur;                 /* The VDBE cursor for the index */
    int nExtraReg = 0;           /* Number of extra registers needed */
    int op;                      /* Instruction opcode */
    char *zStartAff;             /* Affinity for start of range constraint */
    char cEndAff = 0;            /* Affinity for end of range constraint */
    u8 bSeekPastNull = 0;        /* True to seek past initial nulls */
    u8 bStopAtNull = 0;          /* Add condition to terminate at NULLs */

    pIdx = pLoop->u.btree.pIndex;
    iIdxCur = pLevel->iIdxCur;
    assert( nEq>=pLoop->nSkip );

    /* If this loop satisfies a sort order (pOrderBy) request that 
    ** was passed to this function to implement a "SELECT min(x) ..." 
    ** query, then the caller will only allow the loop to run for
    ** a single iteration. This means that the first row returned
    ** should not have a NULL value stored in 'x'. If column 'x' is
    ** the first one after the nEq equality constraints in the index,
    ** this requires some special handling.
    */
    assert( pWInfo->pOrderBy==0
         || pWInfo->pOrderBy->nExpr==1
         || (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0 );
    if( (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)!=0
     && pWInfo->nOBSat>0
     && (pIdx->nKeyCol>nEq)
    ){
      assert( pLoop->nSkip==0 );
      bSeekPastNull = 1;
      nExtraReg = 1;
    }

    /* Find any inequality constraint terms for the start and end 
    ** of the range. 
    */
    j = nEq;
    if( pLoop->wsFlags & WHERE_BTM_LIMIT ){
      pRangeStart = pLoop->aLTerm[j++];
      nExtraReg = 1;
      /* Like optimization range constraints always occur in pairs */
      assert( (pRangeStart->wtFlags & TERM_LIKEOPT)==0 || 
              (pLoop->wsFlags & WHERE_TOP_LIMIT)!=0 );
    }
    if( pLoop->wsFlags & WHERE_TOP_LIMIT ){
      pRangeEnd = pLoop->aLTerm[j++];
      nExtraReg = 1;
      if( (pRangeEnd->wtFlags & TERM_LIKEOPT)!=0 ){
        assert( pRangeStart!=0 );                     /* LIKE opt constraints */
        assert( pRangeStart->wtFlags & TERM_LIKEOPT );   /* occur in pairs */
        pLevel->iLikeRepCntr = ++pParse->nMem;
        testcase( bRev );
        testcase( pIdx->aSortOrder[nEq]==SQLITE_SO_DESC );
        sqlite3VdbeAddOp2(v, OP_Integer,
                          bRev ^ (pIdx->aSortOrder[nEq]==SQLITE_SO_DESC),
                          pLevel->iLikeRepCntr);
        VdbeComment((v, "LIKE loop counter"));
        pLevel->addrLikeRep = sqlite3VdbeCurrentAddr(v);
      }
      if( pRangeStart==0
       && (j = pIdx->aiColumn[nEq])>=0 
       && pIdx->pTable->aCol[j].notNull==0
      ){
        bSeekPastNull = 1;
      }
    }
    assert( pRangeEnd==0 || (pRangeEnd->wtFlags & TERM_VNULL)==0 );

    /* Generate code to evaluate all constraint terms using == or IN
    ** and store the values of those terms in an array of registers
    ** starting at regBase.
    */
    regBase = codeAllEqualityTerms(pParse,pLevel,bRev,nExtraReg,&zStartAff);
    assert( zStartAff==0 || sqlite3Strlen30(zStartAff)>=nEq );
    if( zStartAff ) cEndAff = zStartAff[nEq];
    addrNxt = pLevel->addrNxt;

    /* If we are doing a reverse order scan on an ascending index, or
    ** a forward order scan on a descending index, interchange the 
    ** start and end terms (pRangeStart and pRangeEnd).
    */
    if( (nEq<pIdx->nKeyCol && bRev==(pIdx->aSortOrder[nEq]==SQLITE_SO_ASC))
     || (bRev && pIdx->nKeyCol==nEq)
    ){
      SWAP(WhereTerm *, pRangeEnd, pRangeStart);
      SWAP(u8, bSeekPastNull, bStopAtNull);
    }

    testcase( pRangeStart && (pRangeStart->eOperator & WO_LE)!=0 );
    testcase( pRangeStart && (pRangeStart->eOperator & WO_GE)!=0 );
    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_LE)!=0 );
    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_GE)!=0 );
    startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE);
    endEq =   !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE);
    start_constraints = pRangeStart || nEq>0;

    /* Seek the index cursor to the start of the range. */
    nConstraint = nEq;
    if( pRangeStart ){
      Expr *pRight = pRangeStart->pExpr->pRight;
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeStart);
      if( (pRangeStart->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( zStartAff ){
        if( sqlite3CompareAffinity(pRight, zStartAff[nEq])==SQLITE_AFF_BLOB){
          /* Since the comparison is to be performed with no conversions
          ** applied to the operands, set the affinity to apply to pRight to 
          ** SQLITE_AFF_BLOB.  */
          zStartAff[nEq] = SQLITE_AFF_BLOB;
        }
        if( sqlite3ExprNeedsNoAffinityChange(pRight, zStartAff[nEq]) ){
          zStartAff[nEq] = SQLITE_AFF_BLOB;
        }
      }  
      nConstraint++;
      testcase( pRangeStart->wtFlags & TERM_VIRTUAL );
    }else if( bSeekPastNull ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
      nConstraint++;
      startEq = 0;
      start_constraints = 1;
    }
    codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff);
    op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
    assert( op!=0 );
    sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
    VdbeCoverage(v);
    VdbeCoverageIf(v, op==OP_Rewind);  testcase( op==OP_Rewind );
    VdbeCoverageIf(v, op==OP_Last);    testcase( op==OP_Last );
    VdbeCoverageIf(v, op==OP_SeekGT);  testcase( op==OP_SeekGT );
    VdbeCoverageIf(v, op==OP_SeekGE);  testcase( op==OP_SeekGE );
    VdbeCoverageIf(v, op==OP_SeekLE);  testcase( op==OP_SeekLE );
    VdbeCoverageIf(v, op==OP_SeekLT);  testcase( op==OP_SeekLT );

    /* Load the value for the inequality constraint at the end of the
    ** range (if any).
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;
      sqlite3ExprCacheRemove(pParse, regBase+nEq, 1);
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      whereLikeOptimizationStringFixup(v, pLevel, pRangeEnd);
      if( (pRangeEnd->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( sqlite3CompareAffinity(pRight, cEndAff)!=SQLITE_AFF_BLOB
       && !sqlite3ExprNeedsNoAffinityChange(pRight, cEndAff)
      ){
        codeApplyAffinity(pParse, regBase+nEq, 1, &cEndAff);
      }
      nConstraint++;
      testcase( pRangeEnd->wtFlags & TERM_VIRTUAL );
    }else if( bStopAtNull ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
      endEq = 0;
      nConstraint++;
    }
    sqlite3DbFree(db, zStartAff);

    /* Top of the loop body */
    pLevel->p2 = sqlite3VdbeCurrentAddr(v);

    /* Check if the index cursor is past the end of the range. */
    if( nConstraint ){
      op = aEndOp[bRev*2 + endEq];
      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
      testcase( op==OP_IdxGT );  VdbeCoverageIf(v, op==OP_IdxGT );
      testcase( op==OP_IdxGE );  VdbeCoverageIf(v, op==OP_IdxGE );
      testcase( op==OP_IdxLT );  VdbeCoverageIf(v, op==OP_IdxLT );
      testcase( op==OP_IdxLE );  VdbeCoverageIf(v, op==OP_IdxLE );
    }

    /* Seek the table cursor, if required */
    disableTerm(pLevel, pRangeStart);
    disableTerm(pLevel, pRangeEnd);
    if( omitTable ){
      /* pIdx is a covering index.  No need to access the main table. */
    }else if( HasRowid(pIdx->pTable) ){
      iRowidReg = ++pParse->nMem;
      sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, iRowidReg);
      sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
      sqlite3VdbeAddOp2(v, OP_Seek, iCur, iRowidReg);  /* Deferred seek */
    }else if( iCur!=iIdxCur ){
      Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable);
      iRowidReg = sqlite3GetTempRange(pParse, pPk->nKeyCol);
      for(j=0; j<pPk->nKeyCol; j++){
        k = sqlite3ColumnOfIndex(pIdx, pPk->aiColumn[j]);
        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k, iRowidReg+j);
      }
      sqlite3VdbeAddOp4Int(v, OP_NotFound, iCur, addrCont,
                           iRowidReg, pPk->nKeyCol); VdbeCoverage(v);
    }

    /* Record the instruction used to terminate the loop. Disable 
    ** WHERE clause terms made redundant by the index range scan.
    */
    if( pLoop->wsFlags & WHERE_ONEROW ){
      pLevel->op = OP_Noop;
    }else if( bRev ){
      pLevel->op = OP_Prev;
    }else{
      pLevel->op = OP_Next;
    }
    pLevel->p1 = iIdxCur;
    pLevel->p3 = (pLoop->wsFlags&WHERE_UNQ_WANTED)!=0 ? 1:0;
    if( (pLoop->wsFlags & WHERE_CONSTRAINT)==0 ){
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }else{
      assert( pLevel->p5==0 );
    }
  }else

#ifndef SQLITE_OMIT_OR_OPTIMIZATION
  if( pLoop->wsFlags & WHERE_MULTI_OR ){
    /* Case 5:  Two or more separately indexed terms connected by OR
    **
    ** Example:
    **
    **   CREATE TABLE t1(a,b,c,d);
    **   CREATE INDEX i1 ON t1(a);
    **   CREATE INDEX i2 ON t1(b);
    **   CREATE INDEX i3 ON t1(c);
    **
    **   SELECT * FROM t1 WHERE a=5 OR b=7 OR (c=11 AND d=13)
    **
    ** In the example, there are three indexed terms connected by OR.
    ** The top of the loop looks like this:
    **
    **          Null       1                # Zero the rowset in reg 1
    **
    ** Then, for each indexed term, the following. The arguments to
    ** RowSetTest are such that the rowid of the current row is inserted
    ** into the RowSet. If it is already present, control skips the
    ** Gosub opcode and jumps straight to the code generated by WhereEnd().
    **
    **        sqlite3WhereBegin(<term>)
    **          RowSetTest                  # Insert rowid into rowset
    **          Gosub      2 A
    **        sqlite3WhereEnd()
    **
    ** Following the above, code to terminate the loop. Label A, the target
    ** of the Gosub above, jumps to the instruction right after the Goto.
    **
    **          Null       1                # Zero the rowset in reg 1
    **          Goto       B                # The loop is finished.
    **
    **       A: <loop body>                 # Return data, whatever.
    **
    **          Return     2                # Jump back to the Gosub
    **
    **       B: <after the loop>
    **
    ** Added 2014-05-26: If the table is a WITHOUT ROWID table, then
    ** use an ephemeral index instead of a RowSet to record the primary
    ** keys of the rows we have already seen.
    **
    */
    WhereClause *pOrWc;    /* The OR-clause broken out into subterms */
    SrcList *pOrTab;       /* Shortened table list or OR-clause generation */
    Index *pCov = 0;             /* Potential covering index (or NULL) */
    int iCovCur = pParse->nTab++;  /* Cursor used for index scans (if any) */

    int regReturn = ++pParse->nMem;           /* Register used with OP_Gosub */
    int regRowset = 0;                        /* Register for RowSet object */
    int regRowid = 0;                         /* Register holding rowid */
    int iLoopBody = sqlite3VdbeMakeLabel(v);  /* Start of loop body */
    int iRetInit;                             /* Address of regReturn init */
    int untestedTerms = 0;             /* Some terms not completely tested */
    int ii;                            /* Loop counter */
    u16 wctrlFlags;                    /* Flags for sub-WHERE clause */
    Expr *pAndExpr = 0;                /* An ".. AND (...)" expression */
    Table *pTab = pTabItem->pTab;
   
    pTerm = pLoop->aLTerm[0];
    assert( pTerm!=0 );
    assert( pTerm->eOperator & WO_OR );
    assert( (pTerm->wtFlags & TERM_ORINFO)!=0 );
    pOrWc = &pTerm->u.pOrInfo->wc;
    pLevel->op = OP_Return;
    pLevel->p1 = regReturn;

    /* Set up a new SrcList in pOrTab containing the table being scanned
    ** by this loop in the a[0] slot and all notReady tables in a[1..] slots.
    ** This becomes the SrcList in the recursive call to sqlite3WhereBegin().
    */
    if( pWInfo->nLevel>1 ){
      int nNotReady;                 /* The number of notReady tables */
      struct SrcList_item *origSrc;     /* Original list of tables */
      nNotReady = pWInfo->nLevel - iLevel - 1;
      pOrTab = sqlite3StackAllocRaw(db,
                            sizeof(*pOrTab)+ nNotReady*sizeof(pOrTab->a[0]));
      if( pOrTab==0 ) return notReady;
      pOrTab->nAlloc = (u8)(nNotReady + 1);
      pOrTab->nSrc = pOrTab->nAlloc;
      memcpy(pOrTab->a, pTabItem, sizeof(*pTabItem));
      origSrc = pWInfo->pTabList->a;
      for(k=1; k<=nNotReady; k++){
        memcpy(&pOrTab->a[k], &origSrc[pLevel[k].iFrom], sizeof(pOrTab->a[k]));
      }
    }else{
      pOrTab = pWInfo->pTabList;
    }

    /* Initialize the rowset register to contain NULL. An SQL NULL is 
    ** equivalent to an empty rowset.  Or, create an ephemeral index
    ** capable of holding primary keys in the case of a WITHOUT ROWID.
    **
    ** Also initialize regReturn to contain the address of the instruction 
    ** immediately following the OP_Return at the bottom of the loop. This
    ** is required in a few obscure LEFT JOIN cases where control jumps
    ** over the top of the loop into the body of it. In this case the 
    ** correct response for the end-of-loop code (the OP_Return) is to 
    ** fall through to the next instruction, just as an OP_Next does if
    ** called on an uninitialized cursor.
    */
    if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
      if( HasRowid(pTab) ){
        regRowset = ++pParse->nMem;
        sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset);
      }else{
        Index *pPk = sqlite3PrimaryKeyIndex(pTab);
        regRowset = pParse->nTab++;
        sqlite3VdbeAddOp2(v, OP_OpenEphemeral, regRowset, pPk->nKeyCol);
        sqlite3VdbeSetP4KeyInfo(pParse, pPk);
      }
      regRowid = ++pParse->nMem;
    }
    iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);

    /* If the original WHERE clause is z of the form:  (x1 OR x2 OR ...) AND y
    ** Then for every term xN, evaluate as the subexpression: xN AND z
    ** That way, terms in y that are factored into the disjunction will
    ** be picked up by the recursive calls to sqlite3WhereBegin() below.
    **
    ** Actually, each subexpression is converted to "xN AND w" where w is
    ** the "interesting" terms of z - terms that did not originate in the
    ** ON or USING clause of a LEFT JOIN, and terms that are usable as 
    ** indices.
    **
    ** This optimization also only applies if the (x1 OR x2 OR ...) term
    ** is not contained in the ON clause of a LEFT JOIN.
    ** See ticket http://www.sqlite.org/src/info/f2369304e4
    */
    if( pWC->nTerm>1 ){
      int iTerm;
      for(iTerm=0; iTerm<pWC->nTerm; iTerm++){
        Expr *pExpr = pWC->a[iTerm].pExpr;
        if( &pWC->a[iTerm] == pTerm ) continue;
        if( ExprHasProperty(pExpr, EP_FromJoin) ) continue;
        if( (pWC->a[iTerm].wtFlags & TERM_VIRTUAL)!=0 ) continue;
        if( (pWC->a[iTerm].eOperator & WO_ALL)==0 ) continue;
        testcase( pWC->a[iTerm].wtFlags & TERM_ORINFO );
        pExpr = sqlite3ExprDup(db, pExpr, 0);
        pAndExpr = sqlite3ExprAnd(db, pAndExpr, pExpr);
      }
      if( pAndExpr ){
        pAndExpr = sqlite3PExpr(pParse, TK_AND, 0, pAndExpr, 0);
      }
    }

    /* Run a separate WHERE clause for each term of the OR clause.  After
    ** eliminating duplicates from other WHERE clauses, the action for each
    ** sub-WHERE clause is to to invoke the main loop body as a subroutine.
    */
    wctrlFlags =  WHERE_OMIT_OPEN_CLOSE
                | WHERE_FORCE_TABLE
                | WHERE_ONETABLE_ONLY
                | WHERE_NO_AUTOINDEX;
    for(ii=0; ii<pOrWc->nTerm; ii++){
      WhereTerm *pOrTerm = &pOrWc->a[ii];
      if( pOrTerm->leftCursor==iCur || (pOrTerm->eOperator & WO_AND)!=0 ){
        WhereInfo *pSubWInfo;           /* Info for single OR-term scan */
        Expr *pOrExpr = pOrTerm->pExpr; /* Current OR clause term */
        int j1 = 0;                     /* Address of jump operation */
        if( pAndExpr && !ExprHasProperty(pOrExpr, EP_FromJoin) ){
          pAndExpr->pLeft = pOrExpr;
          pOrExpr = pAndExpr;
        }
        /* Loop through table entries that match term pOrTerm. */
        WHERETRACE(0xffff, ("Subplan for OR-clause:\n"));
        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0,
                                      wctrlFlags, iCovCur);
        assert( pSubWInfo || pParse->nErr || db->mallocFailed );
        if( pSubWInfo ){
          WhereLoop *pSubLoop;
          int addrExplain = sqlite3WhereExplainOneScan(
              pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0
          );
          sqlite3WhereAddScanStatus(v, pOrTab, &pSubWInfo->a[0], addrExplain);

          /* This is the sub-WHERE clause body.  First skip over
          ** duplicate rows from prior sub-WHERE clauses, and record the
          ** rowid (or PRIMARY KEY) for the current row so that the same
          ** row will be skipped in subsequent sub-WHERE clauses.
          */
          if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
            int r;
            int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
            if( HasRowid(pTab) ){
              r = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, regRowid, 0);
              j1 = sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset, 0, r,iSet);
              VdbeCoverage(v);
            }else{
              Index *pPk = sqlite3PrimaryKeyIndex(pTab);
              int nPk = pPk->nKeyCol;
              int iPk;

              /* Read the PK into an array of temp registers. */
              r = sqlite3GetTempRange(pParse, nPk);
              for(iPk=0; iPk<nPk; iPk++){
                int iCol = pPk->aiColumn[iPk];
                sqlite3ExprCodeGetColumn(pParse, pTab, iCol, iCur, r+iPk, 0);
              }

              /* Check if the temp table already contains this key. If so,
              ** the row has already been included in the result set and
              ** can be ignored (by jumping past the Gosub below). Otherwise,
              ** insert the key into the temp table and proceed with processing
              ** the row.
              **
              ** Use some of the same optimizations as OP_RowSetTest: If iSet
              ** is zero, assume that the key cannot already be present in
              ** the temp table. And if iSet is -1, assume that there is no 
              ** need to insert the key into the temp table, as it will never 
              ** be tested for.  */ 
              if( iSet ){
                j1 = sqlite3VdbeAddOp4Int(v, OP_Found, regRowset, 0, r, nPk);
                VdbeCoverage(v);
              }
              if( iSet>=0 ){
                sqlite3VdbeAddOp3(v, OP_MakeRecord, r, nPk, regRowid);
                sqlite3VdbeAddOp3(v, OP_IdxInsert, regRowset, regRowid, 0);
                if( iSet ) sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
              }

              /* Release the array of temp registers */
              sqlite3ReleaseTempRange(pParse, r, nPk);
            }
          }

          /* Invoke the main loop body as a subroutine */
          sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody);

          /* Jump here (skipping the main loop body subroutine) if the
          ** current sub-WHERE row is a duplicate from prior sub-WHEREs. */
          if( j1 ) sqlite3VdbeJumpHere(v, j1);

          /* The pSubWInfo->untestedTerms flag means that this OR term
          ** contained one or more AND term from a notReady table.  The
          ** terms from the notReady table could not be tested and will
          ** need to be tested later.
          */
          if( pSubWInfo->untestedTerms ) untestedTerms = 1;

          /* If all of the OR-connected terms are optimized using the same
          ** index, and the index is opened using the same cursor number
          ** by each call to sqlite3WhereBegin() made by this loop, it may
          ** be possible to use that index as a covering index.
          **
          ** If the call to sqlite3WhereBegin() above resulted in a scan that
          ** uses an index, and this is either the first OR-connected term
          ** processed or the index is the same as that used by all previous
          ** terms, set pCov to the candidate covering index. Otherwise, set 
          ** pCov to NULL to indicate that no candidate covering index will 
          ** be available.
          */
          pSubLoop = pSubWInfo->a[0].pWLoop;
          assert( (pSubLoop->wsFlags & WHERE_AUTO_INDEX)==0 );
          if( (pSubLoop->wsFlags & WHERE_INDEXED)!=0
           && (ii==0 || pSubLoop->u.btree.pIndex==pCov)
           && (HasRowid(pTab) || !IsPrimaryKeyIndex(pSubLoop->u.btree.pIndex))
          ){
            assert( pSubWInfo->a[0].iIdxCur==iCovCur );
            pCov = pSubLoop->u.btree.pIndex;
            wctrlFlags |= WHERE_REOPEN_IDX;
          }else{
            pCov = 0;
          }

          /* Finish the loop through table entries that match term pOrTerm. */
          sqlite3WhereEnd(pSubWInfo);
        }
      }
    }
    pLevel->u.pCovidx = pCov;
    if( pCov ) pLevel->iIdxCur = iCovCur;
    if( pAndExpr ){
      pAndExpr->pLeft = 0;
      sqlite3ExprDelete(db, pAndExpr);
    }
    sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
    sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk);
    sqlite3VdbeResolveLabel(v, iLoopBody);

    if( pWInfo->nLevel>1 ) sqlite3StackFree(db, pOrTab);
    if( !untestedTerms ) disableTerm(pLevel, pTerm);
  }else
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */

  {
    /* Case 6:  There is no usable index.  We must do a complete
    **          scan of the entire table.
    */
    static const u8 aStep[] = { OP_Next, OP_Prev };
    static const u8 aStart[] = { OP_Rewind, OP_Last };
    assert( bRev==0 || bRev==1 );
    if( pTabItem->isRecursive ){
      /* Tables marked isRecursive have only a single row that is stored in
      ** a pseudo-cursor.  No need to Rewind or Next such cursors. */
      pLevel->op = OP_Noop;
    }else{
      pLevel->op = aStep[bRev];
      pLevel->p1 = iCur;
      pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk);
      VdbeCoverageIf(v, bRev==0);
      VdbeCoverageIf(v, bRev!=0);
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }
  }

#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
  pLevel->addrVisit = sqlite3VdbeCurrentAddr(v);
#endif

  /* Insert code to test every subexpression that can be completely
  ** computed using the current set of tables.
  */
  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
    Expr *pE;
    int skipLikeAddr = 0;
    testcase( pTerm->wtFlags & TERM_VIRTUAL );
    testcase( pTerm->wtFlags & TERM_CODED );
    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
    if( (pTerm->prereqAll & pLevel->notReady)!=0 ){
      testcase( pWInfo->untestedTerms==0
               && (pWInfo->wctrlFlags & WHERE_ONETABLE_ONLY)!=0 );
      pWInfo->untestedTerms = 1;
      continue;
    }
    pE = pTerm->pExpr;
    assert( pE!=0 );
    if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
      continue;
    }
    if( pTerm->wtFlags & TERM_LIKECOND ){
      assert( pLevel->iLikeRepCntr>0 );
      skipLikeAddr = sqlite3VdbeAddOp1(v, OP_IfNot, pLevel->iLikeRepCntr);
      VdbeCoverage(v);
    }
    sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL);
    if( skipLikeAddr ) sqlite3VdbeJumpHere(v, skipLikeAddr);
    pTerm->wtFlags |= TERM_CODED;
  }

  /* Insert code to test for implied constraints based on transitivity
  ** of the "==" operator.
  **
  ** Example: If the WHERE clause contains "t1.a=t2.b" and "t2.b=123"
  ** and we are coding the t1 loop and the t2 loop has not yet coded,
  ** then we cannot use the "t1.a=t2.b" constraint, but we can code
  ** the implied "t1.a=123" constraint.
  */
  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
    Expr *pE, *pEAlt;
    WhereTerm *pAlt;
    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
    if( (pTerm->eOperator & (WO_EQ|WO_IS))==0 ) continue;
    if( (pTerm->eOperator & WO_EQUIV)==0 ) continue;
    if( pTerm->leftCursor!=iCur ) continue;
    if( pLevel->iLeftJoin ) continue;
    pE = pTerm->pExpr;
    assert( !ExprHasProperty(pE, EP_FromJoin) );
    assert( (pTerm->prereqRight & pLevel->notReady)!=0 );
    pAlt = sqlite3WhereFindTerm(pWC, iCur, pTerm->u.leftColumn, notReady,
                    WO_EQ|WO_IN|WO_IS, 0);
    if( pAlt==0 ) continue;
    if( pAlt->wtFlags & (TERM_CODED) ) continue;
    testcase( pAlt->eOperator & WO_EQ );
    testcase( pAlt->eOperator & WO_IS );
    testcase( pAlt->eOperator & WO_IN );
    VdbeModuleComment((v, "begin transitive constraint"));
    pEAlt = sqlite3StackAllocRaw(db, sizeof(*pEAlt));
    if( pEAlt ){
      *pEAlt = *pAlt->pExpr;
      pEAlt->pLeft = pE->pLeft;
      sqlite3ExprIfFalse(pParse, pEAlt, addrCont, SQLITE_JUMPIFNULL);
      sqlite3StackFree(db, pEAlt);
    }
  }

  /* For a LEFT OUTER JOIN, generate code that will record the fact that
  ** at least one row of the right table has matched the left table.  
  */
  if( pLevel->iLeftJoin ){
    pLevel->addrFirst = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->iLeftJoin);
    VdbeComment((v, "record LEFT JOIN hit"));
    sqlite3ExprCacheClear(pParse);
    for(pTerm=pWC->a, j=0; j<pWC->nTerm; j++, pTerm++){
      testcase( pTerm->wtFlags & TERM_VIRTUAL );
      testcase( pTerm->wtFlags & TERM_CODED );
      if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
      if( (pTerm->prereqAll & pLevel->notReady)!=0 ){
        assert( pWInfo->untestedTerms );
        continue;
      }
      assert( pTerm->pExpr );
      sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL);
      pTerm->wtFlags |= TERM_CODED;
    }
  }

  return pLevel->notReady;
}

/************** End of wherecode.c *******************************************/
/************** Begin file whereexpr.c ***************************************/
/*
** 2015-06-08
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.
**
** This file was originally part of where.c but was split out to improve
** readability and editabiliity.  This file contains utility routines for
** analyzing Expr objects in the WHERE clause.
*/

/* Forward declarations */
static void exprAnalyze(SrcList*, WhereClause*, int);

/*
** Deallocate all memory associated with a WhereOrInfo object.
*/
static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){
  sqlite3WhereClauseClear(&p->wc);
  sqlite3DbFree(db, p);
}

/*
** Deallocate all memory associated with a WhereAndInfo object.
*/
static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){
  sqlite3WhereClauseClear(&p->wc);
  sqlite3DbFree(db, p);
}
























/*
** Add a single new WhereTerm entry to the WhereClause object pWC.
** The new WhereTerm object is constructed from Expr p and with wtFlags.
** The index in pWC->a[] of the new WhereTerm is returned on success.
** 0 is returned if the new WhereTerm could not be added due to a memory
** allocation error.  The memory allocation failure will be recorded in
** the db->mallocFailed flag so that higher-level functions can detect it.
................................................................................
  pTerm->pExpr = sqlite3ExprSkipCollate(p);
  pTerm->wtFlags = wtFlags;
  pTerm->pWC = pWC;
  pTerm->iParent = -1;
  return idx;
}





















































































































/*
** Return TRUE if the given operator is one of the operators that is
** allowed for an indexable WHERE clause term.  The allowed operators are
** "=", "<", ">", "<=", ">=", "IN", and "IS NULL"
*/
static int allowedOp(int op){
  assert( TK_GT>TK_EQ && TK_GT<TK_GE );
................................................................................
  assert( op!=TK_LE || c==WO_LE );
  assert( op!=TK_GT || c==WO_GT );
  assert( op!=TK_GE || c==WO_GE );
  assert( op!=TK_IS || c==WO_IS );
  return c;
}



































































































































































































#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
/*
** Check to see if the given expression is a LIKE or GLOB operator that
** can be optimized using inequality constraints.  Return TRUE if it is
** so and false if not.
**
................................................................................
  assert( pLeft->iColumn!=(-1) ); /* Because IPK never has AFF_TEXT */

  pRight = sqlite3ExprSkipCollate(pList->a[0].pExpr);
  op = pRight->op;
  if( op==TK_VARIABLE ){
    Vdbe *pReprepare = pParse->pReprepare;
    int iCol = pRight->iColumn;
    pVal = sqlite3VdbeGetBoundValue(pReprepare, iCol, SQLITE_AFF_BLOB);
    if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){
      z = (char *)sqlite3_value_text(pVal);
    }
    sqlite3VdbeSetVarmask(pParse->pVdbe, iCol);
    assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER );
  }else if( op==TK_STRING ){
    z = pRight->u.zToken;
................................................................................
**
** then create a new virtual term like this:
**
**      x IN (expr1,expr2,expr3)
**
** CASE 2:
**
** If there are exactly two disjuncts and one side has x>A and the other side
** has x=A (for the same x and A) then add a new virtual conjunct term to the
** WHERE clause of the form "x>=A".  Example:
**
**      x>A OR (x=A AND y>B)    adds:    x>=A
**
** The added conjunct can sometimes be helpful in query planning.
**
................................................................................
**
** From another point of view, "indexable" means that the subterm could
** potentially be used with an index if an appropriate index exists.
** This analysis does not consider whether or not the index exists; that
** is decided elsewhere.  This analysis only looks at whether subterms
** appropriate for indexing exist.
**
** All examples A through E above satisfy case 3.  But if a term
** also satisfies case 1 (such as B) we know that the optimizer will
** always prefer case 1, so in that case we pretend that case 3 is not
** satisfied.
**
** It might be the case that multiple tables are indexable.  For example,
** (E) above is indexable on tables P, Q, and R.
**
** Terms that satisfy case 3 are candidates for lookup by using
** separate indices to find rowids for each subterm and composing
** the union of all rowids using a RowSet object.  This is similar
** to "bitmap indices" in other database engines.
**
** OTHERWISE:
**
** If none of cases 1, 2, or 3 apply, then leave the eOperator set to
** zero.  This term is not useful for search.
*/
static void exprAnalyzeOrTerm(
  SrcList *pSrc,            /* the FROM clause */
  WhereClause *pWC,         /* the complete WHERE clause */
  int idxTerm               /* Index of the OR-term to be analyzed */
){
................................................................................
  */
  assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
  assert( pExpr->op==TK_OR );
  pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
  if( pOrInfo==0 ) return;
  pTerm->wtFlags |= TERM_ORINFO;
  pOrWc = &pOrInfo->wc;
  sqlite3WhereClauseInit(pOrWc, pWInfo);
  sqlite3WhereSplit(pOrWc, pExpr, TK_OR);
  sqlite3WhereExprAnalyze(pSrc, pOrWc);
  if( db->mallocFailed ) return;
  assert( pOrWc->nTerm>=2 );

  /*
  ** Compute the set of tables that might satisfy cases 1 or 3.
  */
  indexable = ~(Bitmask)0;
  chngToIN = ~(Bitmask)0;
  for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){
    if( (pOrTerm->eOperator & WO_SINGLE)==0 ){
      WhereAndInfo *pAndInfo;
      assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 );
................................................................................
        WhereTerm *pAndTerm;
        int j;
        Bitmask b = 0;
        pOrTerm->u.pAndInfo = pAndInfo;
        pOrTerm->wtFlags |= TERM_ANDINFO;
        pOrTerm->eOperator = WO_AND;
        pAndWC = &pAndInfo->wc;
        sqlite3WhereClauseInit(pAndWC, pWC->pWInfo);
        sqlite3WhereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
        sqlite3WhereExprAnalyze(pSrc, pAndWC);
        pAndWC->pOuter = pWC;
        testcase( db->mallocFailed );
        if( !db->mallocFailed ){
          for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
            assert( pAndTerm->pExpr );
            if( allowedOp(pAndTerm->pExpr->op) ){
              b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pAndTerm->leftCursor);
            }
          }
        }
        indexable &= b;
      }
    }else if( pOrTerm->wtFlags & TERM_COPIED ){
      /* Skip this term for now.  We revisit it when we process the
      ** corresponding TERM_VIRTUAL term */
    }else{
      Bitmask b;
      b = sqlite3WhereGetMask(&pWInfo->sMaskSet, pOrTerm->leftCursor);
      if( pOrTerm->wtFlags & TERM_VIRTUAL ){
        WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent];
        b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pOther->leftCursor);
      }
      indexable &= b;
      if( (pOrTerm->eOperator & WO_EQ)==0 ){
        chngToIN = 0;
      }else{
        chngToIN &= b;
      }
................................................................................
        pOrTerm->wtFlags &= ~TERM_OR_OK;
        if( pOrTerm->leftCursor==iCursor ){
          /* This is the 2-bit case and we are on the second iteration and
          ** current term is from the first iteration.  So skip this term. */
          assert( j==1 );
          continue;
        }
        if( (chngToIN & sqlite3WhereGetMask(&pWInfo->sMaskSet,
                                            pOrTerm->leftCursor))==0 ){
          /* This term must be of the form t1.a==t2.b where t2 is in the
          ** chngToIN set but t1 is not.  This term will be either preceded
          ** or follwed by an inverted copy (t2.b==t1.a).  Skip this term 
          ** and use its inversion. */
          testcase( pOrTerm->wtFlags & TERM_COPIED );
          testcase( pOrTerm->wtFlags & TERM_VIRTUAL );
          assert( pOrTerm->wtFlags & (TERM_COPIED|TERM_VIRTUAL) );
................................................................................
        break;
      }
      if( i<0 ){
        /* No candidate table+column was found.  This can only occur
        ** on the second iteration */
        assert( j==1 );
        assert( IsPowerOfTwo(chngToIN) );
        assert( chngToIN==sqlite3WhereGetMask(&pWInfo->sMaskSet, iCursor) );
        break;
      }
      testcase( j==1 );

      /* We have found a candidate table and column.  Check to see if that
      ** table and column is common to every term in the OR clause */
      okToChngToIN = 1;
................................................................................

/*
** We already know that pExpr is a binary operator where both operands are
** column references.  This routine checks to see if pExpr is an equivalence
** relation:
**   1.  The SQLITE_Transitive optimization must be enabled
**   2.  Must be either an == or an IS operator
**   3.  Not originating in the ON clause of an OUTER JOIN
**   4.  The affinities of A and B must be compatible
**   5a. Both operands use the same collating sequence OR
**   5b. The overall collating sequence is BINARY
** If this routine returns TRUE, that means that the RHS can be substituted
** for the LHS anyplace else in the WHERE clause where the LHS column occurs.
** This is an optimization.  No harm comes from returning 0.  But if 1 is
** returned when it should not be, then incorrect answers might result.
................................................................................
  /* Since pLeft and pRight are both a column references, their collating
  ** sequence should always be defined. */
  zColl1 = ALWAYS(pColl) ? pColl->zName : 0;
  pColl = sqlite3ExprCollSeq(pParse, pExpr->pRight);
  zColl2 = ALWAYS(pColl) ? pColl->zName : 0;
  return sqlite3StrICmp(zColl1, zColl2)==0;
}

/*
** Recursively walk the expressions of a SELECT statement and generate
** a bitmask indicating which tables are used in that expression
** tree.
*/
static Bitmask exprSelectUsage(WhereMaskSet *pMaskSet, Select *pS){
  Bitmask mask = 0;
  while( pS ){
    SrcList *pSrc = pS->pSrc;
    mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pEList);
    mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pGroupBy);
    mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pOrderBy);
    mask |= sqlite3WhereExprUsage(pMaskSet, pS->pWhere);
    mask |= sqlite3WhereExprUsage(pMaskSet, pS->pHaving);
    if( ALWAYS(pSrc!=0) ){
      int i;
      for(i=0; i<pSrc->nSrc; i++){
        mask |= exprSelectUsage(pMaskSet, pSrc->a[i].pSelect);
        mask |= sqlite3WhereExprUsage(pMaskSet, pSrc->a[i].pOn);
      }
    }
    pS = pS->pPrior;
  }
  return mask;
}

/*
** The input to this routine is an WhereTerm structure with only the
** "pExpr" field filled in.  The job of this routine is to analyze the
** subexpression and populate all the other fields of the WhereTerm
** structure.
**
................................................................................
  if( db->mallocFailed ){
    return;
  }
  pTerm = &pWC->a[idxTerm];
  pMaskSet = &pWInfo->sMaskSet;
  pExpr = pTerm->pExpr;
  assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE );
  prereqLeft = sqlite3WhereExprUsage(pMaskSet, pExpr->pLeft);
  op = pExpr->op;
  if( op==TK_IN ){
    assert( pExpr->pRight==0 );
    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
      pTerm->prereqRight = exprSelectUsage(pMaskSet, pExpr->x.pSelect);
    }else{
      pTerm->prereqRight = sqlite3WhereExprListUsage(pMaskSet, pExpr->x.pList);
    }
  }else if( op==TK_ISNULL ){
    pTerm->prereqRight = 0;
  }else{
    pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->pRight);
  }
  prereqAll = sqlite3WhereExprUsage(pMaskSet, pExpr);
  if( ExprHasProperty(pExpr, EP_FromJoin) ){
    Bitmask x = sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
    prereqAll |= x;
    extraRight = x-1;  /* ON clause terms may not be used with an index
                       ** on left table of a LEFT JOIN.  Ticket #3015 */
  }
  pTerm->prereqAll = prereqAll;
  pTerm->leftCursor = -1;
  pTerm->iParent = -1;
................................................................................
    int idxNew;
    Expr *pRight, *pLeft;
    WhereTerm *pNewTerm;
    Bitmask prereqColumn, prereqExpr;

    pRight = pExpr->x.pList->a[0].pExpr;
    pLeft = pExpr->x.pList->a[1].pExpr;
    prereqExpr = sqlite3WhereExprUsage(pMaskSet, pRight);
    prereqColumn = sqlite3WhereExprUsage(pMaskSet, pLeft);
    if( (prereqExpr & prereqColumn)==0 ){
      Expr *pNewExpr;
      pNewExpr = sqlite3PExpr(pParse, TK_MATCH, 
                              0, sqlite3ExprDup(db, pRight, 0), 0);
      idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
      testcase( idxNew==0 );
      pNewTerm = &pWC->a[idxNew];
................................................................................
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */

  /* Prevent ON clause terms of a LEFT JOIN from being used to drive
  ** an index for tables to the left of the join.
  */
  pTerm->prereqRight |= extraRight;
}

/***************************************************************************
** Routines with file scope above.  Interface to the rest of the where.c
** subsystem follows.
***************************************************************************/

/*
** This routine identifies subexpressions in the WHERE clause where
** each subexpression is separated by the AND operator or some other
** operator specified in the op parameter.  The WhereClause structure
** is filled with pointers to subexpressions.  For example:
**
**    WHERE  a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
**           \________/     \_______________/     \________________/
**            slot[0]            slot[1]               slot[2]
**
** The original WHERE clause in pExpr is unaltered.  All this routine
** does is make slot[] entries point to substructure within pExpr.
**
** In the previous sentence and in the diagram, "slot[]" refers to
** the WhereClause.a[] array.  The slot[] array grows as needed to contain
** all terms of the WHERE clause.
*/
SQLITE_PRIVATE void sqlite3WhereSplit(WhereClause *pWC, Expr *pExpr, u8 op){
  Expr *pE2 = sqlite3ExprSkipCollate(pExpr);
  pWC->op = op;
  if( pE2==0 ) return;
  if( pE2->op!=op ){
    whereClauseInsert(pWC, pExpr, 0);
  }else{
    sqlite3WhereSplit(pWC, pE2->pLeft, op);
    sqlite3WhereSplit(pWC, pE2->pRight, op);
  }
}

/*
** Initialize a preallocated WhereClause structure.
*/
SQLITE_PRIVATE void sqlite3WhereClauseInit(
  WhereClause *pWC,        /* The WhereClause to be initialized */
  WhereInfo *pWInfo        /* The WHERE processing context */
){
  pWC->pWInfo = pWInfo;
  pWC->pOuter = 0;
  pWC->nTerm = 0;
  pWC->nSlot = ArraySize(pWC->aStatic);
  pWC->a = pWC->aStatic;
}

/*
** Deallocate a WhereClause structure.  The WhereClause structure
** itself is not freed.  This routine is the inverse of sqlite3WhereClauseInit().
*/
SQLITE_PRIVATE void sqlite3WhereClauseClear(WhereClause *pWC){
  int i;
  WhereTerm *a;
  sqlite3 *db = pWC->pWInfo->pParse->db;
  for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
    if( a->wtFlags & TERM_DYNAMIC ){
      sqlite3ExprDelete(db, a->pExpr);
    }
    if( a->wtFlags & TERM_ORINFO ){
      whereOrInfoDelete(db, a->u.pOrInfo);
    }else if( a->wtFlags & TERM_ANDINFO ){
      whereAndInfoDelete(db, a->u.pAndInfo);
    }
  }
  if( pWC->a!=pWC->aStatic ){
    sqlite3DbFree(db, pWC->a);
  }
}


/*
** These routines walk (recursively) an expression tree and generate
** a bitmask indicating which tables are used in that expression
** tree.
*/
SQLITE_PRIVATE Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){
  Bitmask mask = 0;
  if( p==0 ) return 0;
  if( p->op==TK_COLUMN ){
    mask = sqlite3WhereGetMask(pMaskSet, p->iTable);
    return mask;
  }
  mask = sqlite3WhereExprUsage(pMaskSet, p->pRight);
  mask |= sqlite3WhereExprUsage(pMaskSet, p->pLeft);
  if( ExprHasProperty(p, EP_xIsSelect) ){
    mask |= exprSelectUsage(pMaskSet, p->x.pSelect);
  }else{
    mask |= sqlite3WhereExprListUsage(pMaskSet, p->x.pList);
  }
  return mask;
}
SQLITE_PRIVATE Bitmask sqlite3WhereExprListUsage(WhereMaskSet *pMaskSet, ExprList *pList){
  int i;
  Bitmask mask = 0;
  if( pList ){
    for(i=0; i<pList->nExpr; i++){
      mask |= sqlite3WhereExprUsage(pMaskSet, pList->a[i].pExpr);
    }
  }
  return mask;
}


/*
** Call exprAnalyze on all terms in a WHERE clause.  
**
** Note that exprAnalyze() might add new virtual terms onto the
** end of the WHERE clause.  We do not want to analyze these new
** virtual terms, so start analyzing at the end and work forward
** so that the added virtual terms are never processed.
*/
SQLITE_PRIVATE void sqlite3WhereExprAnalyze(
  SrcList *pTabList,       /* the FROM clause */
  WhereClause *pWC         /* the WHERE clause to be analyzed */
){
  int i;
  for(i=pWC->nTerm-1; i>=0; i--){
    exprAnalyze(pTabList, pWC, i);
  }
}

/************** End of whereexpr.c *******************************************/
/************** Begin file where.c *******************************************/
/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is responsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
*/

/* Forward declaration of methods */
static int whereLoopResize(sqlite3*, WhereLoop*, int);

/* Test variable that can be set to enable WHERE tracing */
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
/***/ int sqlite3WhereTrace = 0;
#endif


/*
** Return the estimated number of output rows from a WHERE clause
*/
SQLITE_PRIVATE u64 sqlite3WhereOutputRowCount(WhereInfo *pWInfo){
  return sqlite3LogEstToInt(pWInfo->nRowOut);
}

/*
** Return one of the WHERE_DISTINCT_xxxxx values to indicate how this
** WHERE clause returns outputs for DISTINCT processing.
*/
SQLITE_PRIVATE int sqlite3WhereIsDistinct(WhereInfo *pWInfo){
  return pWInfo->eDistinct;
}

/*
** Return TRUE if the WHERE clause returns rows in ORDER BY order.
** Return FALSE if the output needs to be sorted.
*/
SQLITE_PRIVATE int sqlite3WhereIsOrdered(WhereInfo *pWInfo){
  return pWInfo->nOBSat;
}

/*
** Return the VDBE address or label to jump to in order to continue
** immediately with the next row of a WHERE clause.
*/
SQLITE_PRIVATE int sqlite3WhereContinueLabel(WhereInfo *pWInfo){
  assert( pWInfo->iContinue!=0 );
  return pWInfo->iContinue;
}

/*
** Return the VDBE address or label to jump to in order to break
** out of a WHERE loop.
*/
SQLITE_PRIVATE int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
  return pWInfo->iBreak;
}

/*
** Return TRUE if an UPDATE or DELETE statement can operate directly on
** the rowids returned by a WHERE clause.  Return FALSE if doing an
** UPDATE or DELETE might change subsequent WHERE clause results.
**
** If the ONEPASS optimization is used (if this routine returns true)
** then also write the indices of open cursors used by ONEPASS
** into aiCur[0] and aiCur[1].  iaCur[0] gets the cursor of the data
** table and iaCur[1] gets the cursor used by an auxiliary index.
** Either value may be -1, indicating that cursor is not used.
** Any cursors returned will have been opened for writing.
**
** aiCur[0] and aiCur[1] both get -1 if the where-clause logic is
** unable to use the ONEPASS optimization.
*/
SQLITE_PRIVATE int sqlite3WhereOkOnePass(WhereInfo *pWInfo, int *aiCur){
  memcpy(aiCur, pWInfo->aiCurOnePass, sizeof(int)*2);
  return pWInfo->okOnePass;
}

/*
** Move the content of pSrc into pDest
*/
static void whereOrMove(WhereOrSet *pDest, WhereOrSet *pSrc){
  pDest->n = pSrc->n;
  memcpy(pDest->a, pSrc->a, pDest->n*sizeof(pDest->a[0]));
}

/*
** Try to insert a new prerequisite/cost entry into the WhereOrSet pSet.
**
** The new entry might overwrite an existing entry, or it might be
** appended, or it might be discarded.  Do whatever is the right thing
** so that pSet keeps the N_OR_COST best entries seen so far.
*/
static int whereOrInsert(
  WhereOrSet *pSet,      /* The WhereOrSet to be updated */
  Bitmask prereq,        /* Prerequisites of the new entry */
  LogEst rRun,           /* Run-cost of the new entry */
  LogEst nOut            /* Number of outputs for the new entry */
){
  u16 i;
  WhereOrCost *p;
  for(i=pSet->n, p=pSet->a; i>0; i--, p++){
    if( rRun<=p->rRun && (prereq & p->prereq)==prereq ){
      goto whereOrInsert_done;
    }
    if( p->rRun<=rRun && (p->prereq & prereq)==p->prereq ){
      return 0;
    }
  }
  if( pSet->n<N_OR_COST ){
    p = &pSet->a[pSet->n++];
    p->nOut = nOut;
  }else{
    p = pSet->a;
    for(i=1; i<pSet->n; i++){
      if( p->rRun>pSet->a[i].rRun ) p = pSet->a + i;
    }
    if( p->rRun<=rRun ) return 0;
  }
whereOrInsert_done:
  p->prereq = prereq;
  p->rRun = rRun;
  if( p->nOut>nOut ) p->nOut = nOut;
  return 1;
}

/*
** Return the bitmask for the given cursor number.  Return 0 if
** iCursor is not in the set.
*/
SQLITE_PRIVATE Bitmask sqlite3WhereGetMask(WhereMaskSet *pMaskSet, int iCursor){
  int i;
  assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 );
  for(i=0; i<pMaskSet->n; i++){
    if( pMaskSet->ix[i]==iCursor ){
      return MASKBIT(i);
    }
  }
  return 0;
}

/*
** Create a new mask for cursor iCursor.
**
** There is one cursor per table in the FROM clause.  The number of
** tables in the FROM clause is limited by a test early in the
** sqlite3WhereBegin() routine.  So we know that the pMaskSet->ix[]
** array will never overflow.
*/
static void createMask(WhereMaskSet *pMaskSet, int iCursor){
  assert( pMaskSet->n < ArraySize(pMaskSet->ix) );
  pMaskSet->ix[pMaskSet->n++] = iCursor;
}

/*
** Advance to the next WhereTerm that matches according to the criteria
** established when the pScan object was initialized by whereScanInit().
** Return NULL if there are no more matching WhereTerms.
*/
static WhereTerm *whereScanNext(WhereScan *pScan){
  int iCur;            /* The cursor on the LHS of the term */
  int iColumn;         /* The column on the LHS of the term.  -1 for IPK */
  Expr *pX;            /* An expression being tested */
  WhereClause *pWC;    /* Shorthand for pScan->pWC */
  WhereTerm *pTerm;    /* The term being tested */
  int k = pScan->k;    /* Where to start scanning */

  while( pScan->iEquiv<=pScan->nEquiv ){
    iCur = pScan->aEquiv[pScan->iEquiv-2];
    iColumn = pScan->aEquiv[pScan->iEquiv-1];
    while( (pWC = pScan->pWC)!=0 ){
      for(pTerm=pWC->a+k; k<pWC->nTerm; k++, pTerm++){
        if( pTerm->leftCursor==iCur
         && pTerm->u.leftColumn==iColumn
         && (pScan->iEquiv<=2 || !ExprHasProperty(pTerm->pExpr, EP_FromJoin))
        ){
          if( (pTerm->eOperator & WO_EQUIV)!=0
           && pScan->nEquiv<ArraySize(pScan->aEquiv)
          ){
            int j;
            pX = sqlite3ExprSkipCollate(pTerm->pExpr->pRight);
            assert( pX->op==TK_COLUMN );
            for(j=0; j<pScan->nEquiv; j+=2){
              if( pScan->aEquiv[j]==pX->iTable
               && pScan->aEquiv[j+1]==pX->iColumn ){
                  break;
              }
            }
            if( j==pScan->nEquiv ){
              pScan->aEquiv[j] = pX->iTable;
              pScan->aEquiv[j+1] = pX->iColumn;
              pScan->nEquiv += 2;
            }
          }
          if( (pTerm->eOperator & pScan->opMask)!=0 ){
            /* Verify the affinity and collating sequence match */
            if( pScan->zCollName && (pTerm->eOperator & WO_ISNULL)==0 ){
              CollSeq *pColl;
              Parse *pParse = pWC->pWInfo->pParse;
              pX = pTerm->pExpr;
              if( !sqlite3IndexAffinityOk(pX, pScan->idxaff) ){
                continue;
              }
              assert(pX->pLeft);
              pColl = sqlite3BinaryCompareCollSeq(pParse,
                                                  pX->pLeft, pX->pRight);
              if( pColl==0 ) pColl = pParse->db->pDfltColl;
              if( sqlite3StrICmp(pColl->zName, pScan->zCollName) ){
                continue;
              }
            }
            if( (pTerm->eOperator & (WO_EQ|WO_IS))!=0
             && (pX = pTerm->pExpr->pRight)->op==TK_COLUMN
             && pX->iTable==pScan->aEquiv[0]
             && pX->iColumn==pScan->aEquiv[1]
            ){
              testcase( pTerm->eOperator & WO_IS );
              continue;
            }
            pScan->k = k+1;
            return pTerm;
          }
        }
      }
      pScan->pWC = pScan->pWC->pOuter;
      k = 0;
    }
    pScan->pWC = pScan->pOrigWC;
    k = 0;
    pScan->iEquiv += 2;
  }
  return 0;
}

/*
** Initialize a WHERE clause scanner object.  Return a pointer to the
** first match.  Return NULL if there are no matches.
**
** The scanner will be searching the WHERE clause pWC.  It will look
** for terms of the form "X <op> <expr>" where X is column iColumn of table
** iCur.  The <op> must be one of the operators described by opMask.
**
** If the search is for X and the WHERE clause contains terms of the
** form X=Y then this routine might also return terms of the form
** "Y <op> <expr>".  The number of levels of transitivity is limited,
** but is enough to handle most commonly occurring SQL statements.
**
** If X is not the INTEGER PRIMARY KEY then X must be compatible with
** index pIdx.
*/
static WhereTerm *whereScanInit(
  WhereScan *pScan,       /* The WhereScan object being initialized */
  WhereClause *pWC,       /* The WHERE clause to be scanned */
  int iCur,               /* Cursor to scan for */
  int iColumn,            /* Column to scan for */
  u32 opMask,             /* Operator(s) to scan for */
  Index *pIdx             /* Must be compatible with this index */
){
  int j;

  /* memset(pScan, 0, sizeof(*pScan)); */
  pScan->pOrigWC = pWC;
  pScan->pWC = pWC;
  if( pIdx && iColumn>=0 ){
    pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity;
    for(j=0; pIdx->aiColumn[j]!=iColumn; j++){
      if( NEVER(j>pIdx->nColumn) ) return 0;
    }
    pScan->zCollName = pIdx->azColl[j];
  }else{
    pScan->idxaff = 0;
    pScan->zCollName = 0;
  }
  pScan->opMask = opMask;
  pScan->k = 0;
  pScan->aEquiv[0] = iCur;
  pScan->aEquiv[1] = iColumn;
  pScan->nEquiv = 2;
  pScan->iEquiv = 2;
  return whereScanNext(pScan);
}

/*
** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
** where X is a reference to the iColumn of table iCur and <op> is one of
** the WO_xx operator codes specified by the op parameter.
** Return a pointer to the term.  Return 0 if not found.
**
** The term returned might by Y=<expr> if there is another constraint in
** the WHERE clause that specifies that X=Y.  Any such constraints will be
** identified by the WO_EQUIV bit in the pTerm->eOperator field.  The
** aEquiv[] array holds X and all its equivalents, with each SQL variable
** taking up two slots in aEquiv[].  The first slot is for the cursor number
** and the second is for the column number.  There are 22 slots in aEquiv[]
** so that means we can look for X plus up to 10 other equivalent values.
** Hence a search for X will return <expr> if X=A1 and A1=A2 and A2=A3
** and ... and A9=A10 and A10=<expr>.
**
** If there are multiple terms in the WHERE clause of the form "X <op> <expr>"
** then try for the one with no dependencies on <expr> - in other words where
** <expr> is a constant expression of some kind.  Only return entries of
** the form "X <op> Y" where Y is a column in another table if no terms of
** the form "X <op> <const-expr>" exist.   If no terms with a constant RHS
** exist, try to return a term that does not use WO_EQUIV.
*/
SQLITE_PRIVATE WhereTerm *sqlite3WhereFindTerm(
  WhereClause *pWC,     /* The WHERE clause to be searched */
  int iCur,             /* Cursor number of LHS */
  int iColumn,          /* Column number of LHS */
  Bitmask notReady,     /* RHS must not overlap with this mask */
  u32 op,               /* Mask of WO_xx values describing operator */
  Index *pIdx           /* Must be compatible with this index, if not NULL */
){
  WhereTerm *pResult = 0;
  WhereTerm *p;
  WhereScan scan;

  p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx);
  op &= WO_EQ|WO_IS;
  while( p ){
    if( (p->prereqRight & notReady)==0 ){
      if( p->prereqRight==0 && (p->eOperator&op)!=0 ){
        testcase( p->eOperator & WO_IS );
        return p;
      }
      if( pResult==0 ) pResult = p;
    }
    p = whereScanNext(&scan);
  }
  return pResult;
}

/*
** This function searches pList for an entry that matches the iCol-th column
** of index pIdx.
**
** If such an expression is found, its index in pList->a[] is returned. If
** no expression is found, -1 is returned.
................................................................................
  return -1;
}

/*
** Return true if the DISTINCT expression-list passed as the third argument
** is redundant.
**
** A DISTINCT list is redundant if any subset of the columns in the
** DISTINCT list are collectively unique and individually non-null.
*/
static int isDistinctRedundant(
  Parse *pParse,            /* Parsing context */
  SrcList *pTabList,        /* The FROM clause */
  WhereClause *pWC,         /* The WHERE clause */
  ExprList *pDistinct       /* The result set that needs to be DISTINCT */
){
................................................................................
  **   3. All of those index columns for which the WHERE clause does not
  **      contain a "col=X" term are subject to a NOT NULL constraint.
  */
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    if( !IsUniqueIndex(pIdx) ) continue;
    for(i=0; i<pIdx->nKeyCol; i++){
      i16 iCol = pIdx->aiColumn[i];
      if( 0==sqlite3WhereFindTerm(pWC, iBase, iCol, ~(Bitmask)0, WO_EQ, pIdx) ){
        int iIdxCol = findIndexCol(pParse, pDistinct, iBase, pIdx, i);
        if( iIdxCol<0 || pTab->aCol[iCol].notNull==0 ){
          break;
        }
      }
    }
    if( i==pIdx->nKeyCol ){
................................................................................
** Allocate and populate an sqlite3_index_info structure. It is the 
** responsibility of the caller to eventually release the structure
** by passing the pointer returned by this function to sqlite3_free().
*/
static sqlite3_index_info *allocateIndexInfo(
  Parse *pParse,
  WhereClause *pWC,
  Bitmask mUnusable,              /* Ignore terms with these prereqs */
  struct SrcList_item *pSrc,
  ExprList *pOrderBy
){
  int i, j;
  int nTerm;
  struct sqlite3_index_constraint *pIdxCons;
  struct sqlite3_index_orderby *pIdxOrderBy;
................................................................................
  int nOrderBy;
  sqlite3_index_info *pIdxInfo;

  /* Count the number of possible WHERE clause constraints referring
  ** to this virtual table */
  for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
    if( pTerm->leftCursor != pSrc->iCursor ) continue;
    if( pTerm->prereqRight & mUnusable ) continue;
    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
    testcase( pTerm->eOperator & WO_IN );
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_IS );
    testcase( pTerm->eOperator & WO_ALL );
    if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
    if( pTerm->wtFlags & TERM_VNULL ) continue;
................................................................................
  *(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy;
  *(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage =
                                                                   pUsage;

  for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
    u8 op;
    if( pTerm->leftCursor != pSrc->iCursor ) continue;
    if( pTerm->prereqRight & mUnusable ) continue;
    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
    testcase( pTerm->eOperator & WO_IN );
    testcase( pTerm->eOperator & WO_IS );
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_ALL );
    if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
    if( pTerm->wtFlags & TERM_VNULL ) continue;
................................................................................
    WHERETRACE(0x10,("IN row estimate: est=%d\n", nRowEst));
  }
  assert( pBuilder->nRecValid==nRecValid );
  return rc;
}
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */











































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































#ifdef WHERETRACE_ENABLED
/*
** Print the content of a WhereTerm object
*/
static void whereTermPrint(WhereTerm *pTerm, int iTerm){
  if( pTerm==0 ){
................................................................................
    int i;
    for(i=0; i<pWInfo->nLevel; i++){
      WhereLevel *pLevel = &pWInfo->a[i];
      if( pLevel->pWLoop && (pLevel->pWLoop->wsFlags & WHERE_IN_ABLE) ){
        sqlite3DbFree(db, pLevel->u.in.aInLoop);
      }
    }
    sqlite3WhereClauseClear(&pWInfo->sWC);
    while( pWInfo->pLoops ){
      WhereLoop *p = pWInfo->pLoops;
      pWInfo->pLoops = p->pNextLoop;
      whereLoopDelete(db, p);
    }
    sqlite3DbFree(db, pWInfo);
  }
................................................................................
  return rc;
}

#ifndef SQLITE_OMIT_VIRTUALTABLE
/*
** Add all WhereLoop objects for a table of the join identified by
** pBuilder->pNew->iTab.  That table is guaranteed to be a virtual table.
**
** If there are no LEFT or CROSS JOIN joins in the query, both mExtra and
** mUnusable are set to 0. Otherwise, mExtra is a mask of all FROM clause
** entries that occur before the virtual table in the FROM clause and are
** separated from it by at least one LEFT or CROSS JOIN. Similarly, the
** mUnusable mask contains all FROM clause entries that occur after the
** virtual table and are separated from it by at least one LEFT or 
** CROSS JOIN. 
**
** For example, if the query were:
**
**   ... FROM t1, t2 LEFT JOIN t3, t4, vt CROSS JOIN t5, t6;
**
** then mExtra corresponds to (t1, t2) and mUnusable to (t5, t6).
**
** All the tables in mExtra must be scanned before the current virtual 
** table. So any terms for which all prerequisites are satisfied by 
** mExtra may be specified as "usable" in all calls to xBestIndex. 
** Conversely, all tables in mUnusable must be scanned after the current
** virtual table, so any terms for which the prerequisites overlap with
** mUnusable should always be configured as "not-usable" for xBestIndex.
*/
static int whereLoopAddVirtual(
  WhereLoopBuilder *pBuilder,  /* WHERE clause information */

  Bitmask mExtra,              /* Tables that must be scanned before this one */
  Bitmask mUnusable            /* Tables that must be scanned after this one */
){
  WhereInfo *pWInfo;           /* WHERE analysis context */
  Parse *pParse;               /* The parsing context */
  WhereClause *pWC;            /* The WHERE clause */
  struct SrcList_item *pSrc;   /* The FROM clause term to search */
  Table *pTab;
  sqlite3 *db;
................................................................................
  int nConstraint;
  int seenIn = 0;              /* True if an IN operator is seen */
  int seenVar = 0;             /* True if a non-constant constraint is seen */
  int iPhase;                  /* 0: const w/o IN, 1: const, 2: no IN,  2: IN */
  WhereLoop *pNew;
  int rc = SQLITE_OK;

  assert( (mExtra & mUnusable)==0 );
  pWInfo = pBuilder->pWInfo;
  pParse = pWInfo->pParse;
  db = pParse->db;
  pWC = pBuilder->pWC;
  pNew = pBuilder->pNew;
  pSrc = &pWInfo->pTabList->a[pNew->iTab];
  pTab = pSrc->pTab;
  assert( IsVirtual(pTab) );
  pIdxInfo = allocateIndexInfo(pParse, pWC, mUnusable, pSrc,pBuilder->pOrderBy);
  if( pIdxInfo==0 ) return SQLITE_NOMEM;
  pNew->prereq = 0;
  pNew->rSetup = 0;
  pNew->wsFlags = WHERE_VIRTUALTABLE;
  pNew->nLTerm = 0;
  pNew->u.vtab.needFree = 0;
  pUsage = pIdxInfo->aConstraintUsage;
................................................................................
      pTerm = &pWC->a[j];
      switch( iPhase ){
        case 0:    /* Constants without IN operator */
          pIdxCons->usable = 0;
          if( (pTerm->eOperator & WO_IN)!=0 ){
            seenIn = 1;
          }
          if( (pTerm->prereqRight & ~mExtra)!=0 ){
            seenVar = 1;
          }else if( (pTerm->eOperator & WO_IN)==0 ){
            pIdxCons->usable = 1;
          }
          break;
        case 1:    /* Constants with IN operators */
          assert( seenIn );
          pIdxCons->usable = (pTerm->prereqRight & ~mExtra)==0;
          break;
        case 2:    /* Variables without IN */
          assert( seenVar );
          pIdxCons->usable = (pTerm->eOperator & WO_IN)==0;
          break;
        default:   /* Variables with IN */
          assert( seenVar && seenIn );
................................................................................
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

/*
** Add WhereLoop entries to handle OR terms.  This works for either
** btrees or virtual tables.
*/
static int whereLoopAddOr(
  WhereLoopBuilder *pBuilder, 
  Bitmask mExtra, 
  Bitmask mUnusable
){
  WhereInfo *pWInfo = pBuilder->pWInfo;
  WhereClause *pWC;
  WhereLoop *pNew;
  WhereTerm *pTerm, *pWCEnd;
  int rc = SQLITE_OK;
  int iCur;
  WhereClause tempWC;
................................................................................
          for(i=0; i<sSubBuild.pWC->nTerm; i++){
            whereTermPrint(&sSubBuild.pWC->a[i], i);
          }
        }
#endif
#ifndef SQLITE_OMIT_VIRTUALTABLE
        if( IsVirtual(pItem->pTab) ){
          rc = whereLoopAddVirtual(&sSubBuild, mExtra, mUnusable);
        }else
#endif
        {
          rc = whereLoopAddBtree(&sSubBuild, mExtra);
        }
        if( rc==SQLITE_OK ){
          rc = whereLoopAddOr(&sSubBuild, mExtra, mUnusable);
        }
        assert( rc==SQLITE_OK || sCur.n==0 );
        if( sCur.n==0 ){
          sSum.n = 0;
          break;
        }else if( once ){
          whereOrMove(&sSum, &sCur);
................................................................................
static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
  WhereInfo *pWInfo = pBuilder->pWInfo;
  Bitmask mExtra = 0;
  Bitmask mPrior = 0;
  int iTab;
  SrcList *pTabList = pWInfo->pTabList;
  struct SrcList_item *pItem;
  struct SrcList_item *pEnd = &pTabList->a[pWInfo->nLevel];
  sqlite3 *db = pWInfo->pParse->db;

  int rc = SQLITE_OK;

  WhereLoop *pNew;
  u8 priorJointype = 0;

  /* Loop over the tables in the join, from left to right */
  pNew = pBuilder->pNew;
  whereLoopInit(pNew);
  for(iTab=0, pItem=pTabList->a; pItem<pEnd; iTab++, pItem++){
    Bitmask mUnusable = 0;
    pNew->iTab = iTab;
    pNew->maskSelf = sqlite3WhereGetMask(&pWInfo->sMaskSet, pItem->iCursor);
    if( ((pItem->jointype|priorJointype) & (JT_LEFT|JT_CROSS))!=0 ){
      /* This condition is true when pItem is the FROM clause term on the
      ** right-hand-side of a LEFT or CROSS JOIN.  */
      mExtra = mPrior;
    }
    priorJointype = pItem->jointype;
    if( IsVirtual(pItem->pTab) ){
      struct SrcList_item *p;
      for(p=&pItem[1]; p<pEnd; p++){
        if( mUnusable || (p->jointype & (JT_LEFT|JT_CROSS)) ){
          mUnusable |= sqlite3WhereGetMask(&pWInfo->sMaskSet, p->iCursor);
        }
      }
      rc = whereLoopAddVirtual(pBuilder, mExtra, mUnusable);
    }else{
      rc = whereLoopAddBtree(pBuilder, mExtra);
    }
    if( rc==SQLITE_OK ){
      rc = whereLoopAddOr(pBuilder, mExtra, mUnusable);
    }
    mPrior |= pNew->maskSelf;
    if( rc || db->mallocFailed ) break;
  }

  whereLoopClear(db, pNew);
  return rc;
}

/*
** Examine a WherePath (with the addition of the extra WhereLoop of the 5th
** parameters) to see if it outputs rows in the requested ORDER BY
................................................................................
    ** loops.
    */
    for(i=0; i<nOrderBy; i++){
      if( MASKBIT(i) & obSat ) continue;
      pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
      if( pOBExpr->op!=TK_COLUMN ) continue;
      if( pOBExpr->iTable!=iCur ) continue;
      pTerm = sqlite3WhereFindTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn,
                       ~ready, WO_EQ|WO_ISNULL|WO_IS, 0);
      if( pTerm==0 ) continue;
      if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){
        const char *z1, *z2;
        pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
        if( !pColl ) pColl = db->pDfltColl;
        z1 = pColl->zName;
................................................................................
    if( isOrderDistinct ){
      orderDistinctMask |= pLoop->maskSelf;
      for(i=0; i<nOrderBy; i++){
        Expr *p;
        Bitmask mTerm;
        if( MASKBIT(i) & obSat ) continue;
        p = pOrderBy->a[i].pExpr;
        mTerm = sqlite3WhereExprUsage(&pWInfo->sMaskSet,p);
        if( mTerm==0 && !sqlite3ExprIsConstant(p) ) continue;
        if( (mTerm&~orderDistinctMask)==0 ){
          obSat |= MASKBIT(i);
        }
      }
    }
  } /* End the loop over all WhereLoops from outer-most down to inner-most */
................................................................................
  
  pWInfo = pBuilder->pWInfo;
  if( pWInfo->wctrlFlags & WHERE_FORCE_TABLE ) return 0;
  assert( pWInfo->pTabList->nSrc>=1 );
  pItem = pWInfo->pTabList->a;
  pTab = pItem->pTab;
  if( IsVirtual(pTab) ) return 0;
  if( pItem->zIndexedBy ) return 0;
  iCur = pItem->iCursor;
  pWC = &pWInfo->sWC;
  pLoop = pBuilder->pNew;
  pLoop->wsFlags = 0;
  pLoop->nSkip = 0;
  pTerm = sqlite3WhereFindTerm(pWC, iCur, -1, 0, WO_EQ|WO_IS, 0);
  if( pTerm ){
    testcase( pTerm->eOperator & WO_IS );
    pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_IPK|WHERE_ONEROW;
    pLoop->aLTerm[0] = pTerm;
    pLoop->nLTerm = 1;
    pLoop->u.btree.nEq = 1;
    /* TUNING: Cost of a rowid lookup is 10 */
................................................................................
      assert( pLoop->aLTermSpace==pLoop->aLTerm );
      if( !IsUniqueIndex(pIdx)
       || pIdx->pPartIdxWhere!=0 
       || pIdx->nKeyCol>ArraySize(pLoop->aLTermSpace) 
      ) continue;
      opMask = pIdx->uniqNotNull ? (WO_EQ|WO_IS) : WO_EQ;
      for(j=0; j<pIdx->nKeyCol; j++){
        pTerm = sqlite3WhereFindTerm(pWC, iCur, pIdx->aiColumn[j], 0, opMask, pIdx);
        if( pTerm==0 ) break;
        testcase( pTerm->eOperator & WO_IS );
        pLoop->aLTerm[j] = pTerm;
      }
      if( j!=pIdx->nKeyCol ) continue;
      pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED;
      if( pIdx->isCovering || (pItem->colUsed & ~columnsInIndex(pIdx))==0 ){
................................................................................
      pLoop->rRun = 39;  /* 39==sqlite3LogEst(15) */
      break;
    }
  }
  if( pLoop->wsFlags ){
    pLoop->nOut = (LogEst)1;
    pWInfo->a[0].pWLoop = pLoop;
    pLoop->maskSelf = sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur);
    pWInfo->a[0].iTabCur = iCur;
    pWInfo->nRowOut = 1;
    if( pWInfo->pOrderBy ) pWInfo->nOBSat =  pWInfo->pOrderBy->nExpr;
    if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){
      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
    }
#ifdef SQLITE_DEBUG
................................................................................
  sWLB.pNew->cId = '*';
#endif

  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.
  */
  initMaskSet(pMaskSet);
  sqlite3WhereClauseInit(&pWInfo->sWC, pWInfo);
  sqlite3WhereSplit(&pWInfo->sWC, pWhere, TK_AND);
    
  /* Special case: a WHERE clause that is constant.  Evaluate the
  ** expression and either jump over all of the code or fall thru.
  */
  for(ii=0; ii<sWLB.pWC->nTerm; ii++){
    if( nTabList==0 || sqlite3ExprIsConstantNotJoin(sWLB.pWC->a[ii].pExpr) ){
      sqlite3ExprIfFalse(pParse, sWLB.pWC->a[ii].pExpr, pWInfo->iBreak,
................................................................................
  for(ii=0; ii<pTabList->nSrc; ii++){
    createMask(pMaskSet, pTabList->a[ii].iCursor);
  }
#ifndef NDEBUG
  {
    Bitmask toTheLeft = 0;
    for(ii=0; ii<pTabList->nSrc; ii++){
      Bitmask m = sqlite3WhereGetMask(pMaskSet, pTabList->a[ii].iCursor);
      assert( (m-1)==toTheLeft );
      toTheLeft |= m;
    }
  }
#endif

  /* Analyze all of the subexpressions. */




  sqlite3WhereExprAnalyze(pTabList, &pWInfo->sWC);
  if( db->mallocFailed ) goto whereBeginError;



  if( wctrlFlags & WHERE_WANT_DISTINCT ){
    if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){
      /* The DISTINCT marking is pointless.  Ignore it. */
      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
    }else if( pOrderBy==0 ){
      /* Try to ORDER BY the result set to make distinct processing easier */
................................................................................
      pWInfo->pOrderBy = pResultSet;
    }
  }

  /* Construct the WhereLoop objects */
  WHERETRACE(0xffff,("*** Optimizer Start ***\n"));
#if defined(WHERETRACE_ENABLED)
  if( sqlite3WhereTrace & 0x100 ){ /* Display all terms of the WHERE clause */

    int i;
    for(i=0; i<sWLB.pWC->nTerm; i++){
      whereTermPrint(&sWLB.pWC->a[i], i);
    }
  }
#endif

  if( nTabList!=1 || whereShortCut(&sWLB)==0 ){
    rc = whereLoopAddAll(&sWLB);
    if( rc ) goto whereBeginError;
  

#ifdef WHERETRACE_ENABLED
    if( sqlite3WhereTrace ){    /* Display all of the WhereLoop objects */
      WhereLoop *p;
      int i;
      static const char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz"
                                             "ABCDEFGHIJKLMNOPQRSTUVWYXZ";
      for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){
        p->cId = zLabel[i%sizeof(zLabel)];
        whereLoopPrint(p, sWLB.pWC);
      }
    }
#endif
  
................................................................................
  }
  if( pWInfo->pOrderBy==0 && (db->flags & SQLITE_ReverseOrder)!=0 ){
     pWInfo->revMask = (Bitmask)(-1);
  }
  if( pParse->nErr || NEVER(db->mallocFailed) ){
    goto whereBeginError;
  }
#ifdef WHERETRACE_ENABLED
  if( sqlite3WhereTrace ){
    sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo->nRowOut);
    if( pWInfo->nOBSat>0 ){
      sqlite3DebugPrintf(" ORDERBY=%d,0x%llx", pWInfo->nOBSat, pWInfo->revMask);
    }
    switch( pWInfo->eDistinct ){
      case WHERE_DISTINCT_UNIQUE: {
................................................................................
  }
#endif
  /* Attempt to omit tables from the join that do not effect the result */
  if( pWInfo->nLevel>=2
   && pResultSet!=0
   && OptimizationEnabled(db, SQLITE_OmitNoopJoin)
  ){
    Bitmask tabUsed = sqlite3WhereExprListUsage(pMaskSet, pResultSet);
    if( sWLB.pOrderBy ){
      tabUsed |= sqlite3WhereExprListUsage(pMaskSet, sWLB.pOrderBy);
    }
    while( pWInfo->nLevel>=2 ){
      WhereTerm *pTerm, *pEnd;
      pLoop = pWInfo->a[pWInfo->nLevel-1].pWLoop;
      if( (pWInfo->pTabList->a[pLoop->iTab].jointype & JT_LEFT)==0 ) break;
      if( (wctrlFlags & WHERE_WANT_DISTINCT)==0
       && (pLoop->wsFlags & WHERE_ONEROW)==0
      ){
................................................................................
  }
  WHERETRACE(0xffff,("*** Optimizer Finished ***\n"));
  pWInfo->pParse->nQueryLoop += pWInfo->nRowOut;

  /* If the caller is an UPDATE or DELETE statement that is requesting
  ** to use a one-pass algorithm, determine if this is appropriate.
  ** The one-pass algorithm only works if the WHERE clause constrains
  ** the statement to update or delete a single row.
  */
  assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 
   && (pWInfo->a[0].pWLoop->wsFlags & WHERE_ONEROW)!=0 ){
    pWInfo->okOnePass = 1;
    if( HasRowid(pTabList->a[0].pTab) ){
      pWInfo->a[0].pWLoop->wsFlags &= ~WHERE_IDX_ONLY;
    }
  }

  /* Open all tables in the pTabList and any indices selected for
  ** searching those tables.
  */

  for(ii=0, pLevel=pWInfo->a; ii<nTabList; ii++, pLevel++){
    Table *pTab;     /* Table to open */
    int iDb;         /* Index of database containing table/index */
    struct SrcList_item *pTabItem;

    pTabItem = &pTabList->a[pLevel->iFrom];
    pTab = pTabItem->pTab;
................................................................................
        Bitmask b = pTabItem->colUsed;
        int n = 0;
        for(; b; b=b>>1, n++){}
        sqlite3VdbeChangeP4(v, sqlite3VdbeCurrentAddr(v)-1, 
                            SQLITE_INT_TO_PTR(n), P4_INT32);
        assert( n<=pTab->nCol );
      }
#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
      sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, pTabItem->iCursor, 0, 0,
                            (const u8*)&pTabItem->colUsed, P4_INT64);
#endif
    }else{
      sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
    }
    if( pLoop->wsFlags & WHERE_INDEXED ){
      Index *pIx = pLoop->u.btree.pIndex;
      int iIndexCur;
      int op = OP_OpenRead;
................................................................................
        if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0
         && (pLoop->wsFlags & (WHERE_COLUMN_RANGE|WHERE_SKIPSCAN))==0
         && (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0
        ){
          sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ); /* Hint to COMDB2 */
        }
        VdbeComment((v, "%s", pIx->zName));
#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
        {
          u64 colUsed = 0;
          int ii, jj;
          for(ii=0; ii<pIx->nColumn; ii++){
            jj = pIx->aiColumn[ii];
            if( jj<0 ) continue;
            if( jj>63 ) jj = 63;
            if( (pTabItem->colUsed & MASKBIT(jj))==0 ) continue;
            colUsed |= ((u64)1)<<(ii<63 ? ii : 63);
          }
          sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, iIndexCur, 0, 0,
                                (u8*)&colUsed, P4_INT64);
        }
#endif /* SQLITE_ENABLE_COLUMN_USED_MASK */
      }
    }
    if( iDb>=0 ) sqlite3CodeVerifySchema(pParse, iDb);

  }
  pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
  if( db->mallocFailed ) goto whereBeginError;

  /* Generate the code to do the search.  Each iteration of the for
  ** loop below generates code for a single nested loop of the VM
  ** program.
................................................................................
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){
      constructAutomaticIndex(pParse, &pWInfo->sWC,
                &pTabList->a[pLevel->iFrom], notReady, pLevel);
      if( db->mallocFailed ) goto whereBeginError;
    }
#endif
    addrExplain = sqlite3WhereExplainOneScan(
        pParse, pTabList, pLevel, ii, pLevel->iFrom, wctrlFlags
    );
    pLevel->addrBody = sqlite3VdbeCurrentAddr(v);
    notReady = sqlite3WhereCodeOneLoopStart(pWInfo, ii, notReady);
    pWInfo->iContinue = pLevel->addrCont;
    if( (wsFlags&WHERE_MULTI_OR)==0 && (wctrlFlags&WHERE_ONETABLE_ONLY)==0 ){
      sqlite3WhereAddScanStatus(v, pTabList, pLevel, addrExplain);
    }
  }

  /* Done. */
  VdbeModuleComment((v, "Begin WHERE-core"));
  return pWInfo;

................................................................................
    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,  /* Cx */
    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,  /* Dx */
    0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,  /* Ex */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0,  /* Fx */
};
#define IdChar(C)  (((c=C)>=0x42 && sqlite3IsEbcdicIdChar[c-0x40]))
#endif

/* Make the IdChar function accessible from ctime.c */
#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
SQLITE_PRIVATE int sqlite3IsIdChar(u8 c){ return IdChar(c); }
#endif


/*
** Return the length of the token that begins at z[0]. 
** Store the token type in *tokenType before returning.
*/
SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *z, int *tokenType){
................................................................................
#if SQLITE_TEMP_STORE==1
  return ( db->temp_store==2 );
#endif
#if SQLITE_TEMP_STORE==2
  return ( db->temp_store!=1 );
#endif
#if SQLITE_TEMP_STORE==3
  UNUSED_PARAMETER(db);
  return 1;
#endif
#if SQLITE_TEMP_STORE<1 || SQLITE_TEMP_STORE>3
  UNUSED_PARAMETER(db);
  return 0;
#endif
}

/*
** Return UTF-8 encoded English language explanation of the most recent
** error.
................................................................................
}

/*
** Interface to the testing logic.
*/
SQLITE_API int SQLITE_CDECL sqlite3_test_control(int op, ...){
  int rc = 0;
#ifdef SQLITE_OMIT_BUILTIN_TEST
  UNUSED_PARAMETER(op);
#else
  va_list ap;
  va_start(ap, op);
  switch( op ){

    /*
    ** Save the current state of the PRNG.
    */
................................................................................
  int prevEscape = 0;     /* True if the previous character was uEsc */

  while( zPattern[iPattern]!=0 ){

    /* Read (and consume) the next character from the input pattern. */
    UChar32 uPattern;
    U8_NEXT_UNSAFE(zPattern, iPattern, uPattern);


    /* There are now 4 possibilities:
    **
    **     1. uPattern is an unescaped match-all character "%",
    **     2. uPattern is an unescaped match-one character "_",
    **     3. uPattern is an unescaped escape character, or
    **     4. uPattern is to be handled as an ordinary character
................................................................................
  UErrorCode status = U_ZERO_ERROR;
  const char *zLocale;      /* Locale identifier - (eg. "jp_JP") */
  const char *zName;        /* SQL Collation sequence name (eg. "japanese") */
  UCollator *pUCollator;    /* ICU library collation object */
  int rc;                   /* Return code from sqlite3_create_collation_x() */

  assert(nArg==2);
  (void)nArg; /* Unused parameter */
  zLocale = (const char *)sqlite3_value_text(apArg[0]);
  zName = (const char *)sqlite3_value_text(apArg[1]);

  if( !zLocale || !zName ){
    return;
  }

................................................................................
  return SQLITE_OK;
}

/*
** The set of routines that implement the simple tokenizer
*/
static const sqlite3_tokenizer_module icuTokenizerModule = {
  0,                           /* iVersion    */
  icuCreate,                   /* xCreate     */
  icuDestroy,                  /* xCreate     */
  icuOpen,                     /* xOpen       */
  icuClose,                    /* xClose      */
  icuNext,                     /* xNext       */
  0,                           /* xLanguageid */
};

/*
** Set *ppModule to point at the implementation of the ICU tokenizer.
*/
SQLITE_PRIVATE void sqlite3Fts3IcuTokenizerModule(
  sqlite3_tokenizer_module const**ppModule