System.Data.SQLite
Check-in [29f36edc2d]
Not logged in

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Update embedded virtual table methods documentation comments using the new tool.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | vtabDocComments
Files: files | file ages | folders
SHA1: 29f36edc2d574370d8b6530a10845c0644abb8e7
User & Date: mistachkin 2015-10-18 05:32:42
Context
2015-10-18
20:07
Preserve selected HTML tags when processing the virtual table methods documentation into the CHM file. check-in: 42512a2bfb user: mistachkin tags: vtabDocComments
05:32
Update embedded virtual table methods documentation comments using the new tool. check-in: 29f36edc2d user: mistachkin tags: vtabDocComments
05:31
Move the 'vtab.html' file so it does not get included in the CHM build. check-in: 5b3dc8f442 user: mistachkin tags: vtabDocComments
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to System.Data.SQLite/ISQLiteNativeModule.cs.

11
12
13
14
15
16
17






18
19
20
21
22
23

24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66











































































































67
68
69
70
71
72
73
...
101
102
103
104
105
106
107






108
109
110

111
112
113
114
115
116
117
118
119
120
121
122
123

124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145

146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
...
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235

236
237
238
239
240
241

242
243
244
245




246
247
248









249
250
251
252
253
254
255
256
257

258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334

335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353

354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417












418
419
420

421
422
423
424

425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
...
453
454
455
456
457
458
459



460
461
462

463
464
465

466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
...
484
485
486
487
488
489
490



491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
...
515
516
517
518
519
520
521



522
523
524
525
526
527
528
529
530
531

532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
...
563
564
565
566
567
568
569



570
571

572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
...
592
593
594
595
596
597
598




599
600
601
602
603
604

605
606
607
608
609
610
611
612
613
614
615
616
617

618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
...
655
656
657
658
659
660
661



662
663
664
665
666

667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
...
686
687
688
689
690
691
692



693
694
695
696
697
698
699
700
701
702
703
704
...
709
710
711
712
713
714
715



716
717
718

719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
...
766
767
768
769
770
771
772



773
774
775

776
777
778
779
780
781
782
783
784
785
786
787
788
...
795
796
797
798
799
800
801








802
803
804
805
806
807
808
809
810
811
812
813
814
815

816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844

845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884

885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
...
936
937
938
939
940
941
942



943
944
945

946
947
948
949
950

951
952
953
954
955
956
957
958
959
960
961
...
963
964
965
966
967
968
969



970
971

972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
...
989
990
991
992
993
994
995



996
997
998
999

1000
1001
1002
1003
1004
1005
1006
....
1012
1013
1014
1015
1016
1017
1018



1019
1020
1021
1022

1023
1024
1025
1026
1027
1028
1029
....
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045








1046
1047
1048
1049



















1050
1051
1052
1053
1054
1055
1056
....
1077
1078
1079
1080
1081
1082
1083



1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
....
1106
1107
1108
1109
1110
1111
1112





1113
1114
1115
1116
1117
1118
1119
1120

1121
1122

1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
....
1146
1147
1148
1149
1150
1151
1152





1153
1154
1155
1156
1157
1158
1159
1160

1161
1162

1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
....
1187
1188
1189
1190
1191
1192
1193





1194
1195
1196
1197
1198
1199
1200
1201

1202
1203

1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
    /// <summary>
    /// This interface represents a virtual table implementation written in
    /// native code.
    /// </summary>
    public interface ISQLiteNativeModule
    {
        /// <summary>






        /// <para>
        /// This method is called to create a new instance of a virtual table
        /// in response to a CREATE VIRTUAL TABLE statement. The db parameter
        /// is a pointer to the SQLite database connection that is executing
        /// the CREATE VIRTUAL TABLE statement. The pAux argument is the copy
        /// of the client data pointer that was the fourth argument to the

        /// sqlite3_create_module() or sqlite3_create_module_v2() call that
        /// registered the virtual table module. The argv parameter is an
        /// array of argc pointers to null terminated strings. The first
        /// string, argv[0], is the name of the module being invoked. The
        /// module name is the name provided as the second argument to
        /// sqlite3_create_module() and as the argument to the USING clause of
        /// the CREATE VIRTUAL TABLE statement that is running. The second,
        /// argv[1], is the name of the database in which the new virtual table
        /// is being created. The database name is "main" for the primary
        /// database, or "temp" for TEMP database, or the name given at the
        /// end of the ATTACH statement for attached databases. The third
        /// element of the array, argv[2], is the name of the new virtual
        /// table, as specified following the TABLE keyword in the CREATE
        /// VIRTUAL TABLE statement. If present, the fourth and subsequent
        /// strings in the argv[] array report the arguments to the module name
        /// in the CREATE VIRTUAL TABLE statement.
        /// </para>
        /// <para>
        /// The job of this method is to construct the new virtual table object
        /// (an sqlite3_vtab object) and return a pointer to it in *ppVTab.
        /// </para>
        /// <para>
        /// As part of the task of creating a new sqlite3_vtab structure, this
        /// method must invoke sqlite3_declare_vtab() to tell the SQLite core
        /// about the columns and datatypes in the virtual table. The
        /// sqlite3_declare_vtab() API has the following prototype:
        /// </para>
        /// <para>
        /// <code>
        /// int sqlite3_declare_vtab(sqlite3 *db, const char *zCreateTable)
        /// </code>
        /// </para>
        /// <para>
        /// The first argument to sqlite3_declare_vtab() must be the same
        /// database connection pointer as the first parameter to this method.
        /// The second argument to sqlite3_declare_vtab() must a
        /// zero-terminated UTF-8 string that contains a well-formed CREATE
        /// TABLE statement that defines the columns in the virtual table and
        /// their data types. The name of the table in this CREATE TABLE
        /// statement is ignored, as are all constraints. Only the column names
        /// and datatypes matter. The CREATE TABLE statement string need not to
        /// be held in persistent memory. The string can be deallocated and/or
        /// reused as soon as the sqlite3_declare_vtab() routine returns.











































































































        /// </para>
        /// </summary>
        /// <param name="pDb">
        /// The native database connection handle.
        /// </param>
        /// <param name="pAux">
        /// The original native pointer value that was provided to the
................................................................................
            ref IntPtr pVtab,
            ref IntPtr pError
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>






        /// <para>
        /// The xConnect method is very similar to xCreate. It has the same
        /// parameters and constructs a new sqlite3_vtab structure just like

        /// xCreate. And it must also call sqlite3_declare_vtab() like xCreate.
        /// </para>
        /// <para>
        /// The difference is that xConnect is called to establish a new
        /// connection to an existing virtual table whereas xCreate is called
        /// to create a new virtual table from scratch.
        /// </para>
        /// <para>
        /// The xCreate and xConnect methods are only different when the
        /// virtual table has some kind of backing store that must be
        /// initialized the first time the virtual table is created. The
        /// xCreate method creates and initializes the backing store. The
        /// xConnect method just connects to an existing backing store.

        /// </para>
        /// <para>
        /// As an example, consider a virtual table implementation that
        /// provides read-only access to existing comma-separated-value (CSV)
        /// files on disk. There is no backing store that needs to be created
        /// or initialized for such a virtual table (since the CSV files
        /// already exist on disk) so the xCreate and xConnect methods will be
        /// identical for that module.
        /// </para>
        /// <para>
        /// Another example is a virtual table that implements a full-text
        /// index. The xCreate method must create and initialize data
        /// structures to hold the dictionary and posting lists for that index.
        /// The xConnect method, on the other hand, only has to locate and use
        /// an existing dictionary and posting lists that were created by a
        /// prior xCreate call.
        /// </para>
        /// <para>
        /// The xConnect method must return SQLITE_OK if it is successful in
        /// creating the new virtual table, or SQLITE_ERROR if it is not
        /// successful. If not successful, the sqlite3_vtab structure must not
        /// be allocated. An error message may optionally be returned in *pzErr

        /// if unsuccessful. Space to hold the error message string must be
        /// allocated using an SQLite memory allocation function like
        /// sqlite3_malloc() or sqlite3_mprintf() as the SQLite core will
        /// attempt to free the space using sqlite3_free() after the error has
        /// been reported up to the application.
        /// </para>
        /// <para>
        /// The xConnect method is required for every virtual table
        /// implementation, though the xCreate and xConnect pointers of the
        /// sqlite3_module object may point to the same function the virtual
        /// table does not need to initialize backing store.
        /// </para>
        /// </summary>
        /// <param name="pDb">
        /// The native database connection handle.
        /// </param>
        /// <param name="pAux">
        /// The original native pointer value that was provided to the
................................................................................
            ref IntPtr pError
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para>
        /// SQLite uses the xBestIndex method of a virtual table module to
        /// determine the best way to access the virtual table. The xBestIndex
        /// method has a prototype like this:
        /// </para>
        /// <code>
        /// int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
        /// </code>
        /// <para>
        /// The SQLite core communicates with the xBestIndex method by filling
        /// in certain fields of the sqlite3_index_info structure and passing a
        /// pointer to that structure into xBestIndex as the second parameter.
        /// The xBestIndex method fills out other fields of this structure
        /// which forms the reply. The sqlite3_index_info structure looks like
        /// this:
        /// </para>
        /// <code>
        ///  struct sqlite3_index_info {
        ///    /* Inputs */
        ///    const int nConstraint;   /* Number of entries in aConstraint */
        ///    const struct sqlite3_index_constraint {
        ///       int iColumn;          /* Column on left-hand side of
        ///                              * constraint */
        ///       unsigned char op;     /* Constraint operator */
        ///       unsigned char usable; /* True if this constraint is usable */
        ///       int iTermOffset;      /* Used internally - xBestIndex should
        ///                              * ignore */
        ///    } *const aConstraint;    /* Table of WHERE clause constraints */
        ///    const int nOrderBy;      /* Number of terms in the ORDER BY
        ///                              * clause */
        ///    const struct sqlite3_index_orderby {
        ///       int iColumn;          /* Column number */
        ///       unsigned char desc;   /* True for DESC.  False for ASC. */
        ///    } *const aOrderBy;       /* The ORDER BY clause */
        ///    /* Outputs */
        ///    struct sqlite3_index_constraint_usage {
        ///      int argvIndex;         /* if greater than zero, constraint is
        ///                              * part of argv to xFilter */

        ///      unsigned char omit;    /* Do not code a test for this
        ///                              * constraint */
        ///    } *const aConstraintUsage;
        ///    int idxNum;              /* Number used to identify the index */
        ///    char *idxStr;            /* String, possibly obtained from
        ///                              * sqlite3_malloc() */

        ///    int needToFreeIdxStr;    /* Free idxStr using sqlite3_free() if
        ///                              * true */
        ///    int orderByConsumed;     /* True if output is already ordered */
        ///    double estimatedCost;    /* Estimated cost of using this index */




        ///  };
        /// </code>
        /// <para>









        /// In addition, there are some defined constants:
        /// </para>
        /// <code>
        ///  #define SQLITE_INDEX_CONSTRAINT_EQ    2
        ///  #define SQLITE_INDEX_CONSTRAINT_GT    4
        ///  #define SQLITE_INDEX_CONSTRAINT_LE    8
        ///  #define SQLITE_INDEX_CONSTRAINT_LT    16
        ///  #define SQLITE_INDEX_CONSTRAINT_GE    32
        ///  #define SQLITE_INDEX_CONSTRAINT_MATCH 64

        /// </code>
        /// <para>
        /// The SQLite core calls the xBestIndex method when it is compiling a
        /// query that involves a virtual table. In other words, SQLite calls
        /// this method when it is running sqlite3_prepare() or the equivalent.
        /// By calling this method, the SQLite core is saying to the virtual
        /// table that it needs to access some subset of the rows in the
        /// virtual table and it wants to know the most efficient way to do
        /// that access. The xBestIndex method replies with information that
        /// the SQLite core can then use to conduct an efficient search of the
        /// virtual table.
        /// </para>
        /// <para>
        /// While compiling a single SQL query, the SQLite core might call
        /// xBestIndex multiple times with different settings in
        /// sqlite3_index_info. The SQLite core will then select the
        /// combination that appears to give the best performance.
        /// </para>
        /// <para>
        /// Before calling this method, the SQLite core initializes an instance
        /// of the sqlite3_index_info structure with information about the
        /// query that it is currently trying to process. This information
        /// derives mainly from the WHERE clause and ORDER BY or GROUP BY
        /// clauses of the query, but also from any ON or USING clauses if the
        /// query is a join. The information that the SQLite core provides to
        /// the xBestIndex method is held in the part of the structure that is
        /// marked as "Inputs". The "Outputs" section is initialized to zero.
        /// </para>
        /// <para>
        /// The information in the sqlite3_index_info structure is ephemeral
        /// and may be overwritten or deallocated as soon as the xBestIndex
        /// method returns. If the xBestIndex method needs to remember any part
        /// of the sqlite3_index_info structure, it should make a copy. Care
        /// must be take to store the copy in a place where it will be
        /// deallocated, such as in the idxStr field with needToFreeIdxStr set
        /// to 1.
        /// </para>
        /// <para>
        /// Note that xBestIndex will always be called before xFilter, since
        /// the idxNum and idxStr outputs from xBestIndex are required inputs
        /// to xFilter. However, there is no guarantee that xFilter will be
        /// called following a successful xBestIndex.
        /// </para>
        /// <para>
        /// The xBestIndex method is required for every virtual table
        /// implementation.
        /// </para>
        /// <para>
        /// 2.3.1 Inputs
        /// </para>
        /// <para>
        /// The main thing that the SQLite core is trying to communicate to the
        /// virtual table is the constraints that are available to limit the
        /// number of rows that need to be searched. The aConstraint[] array
        /// contains one entry for each constraint. There will be exactly
        /// nConstraint entries in that array.
        /// </para>
        /// <para>
        /// Each constraint will correspond to a term in the WHERE clause or in
        /// a USING or ON clause that is of the form
        /// </para>
        /// <code>
        ///     column OP EXPR
        /// </code>
        /// <para>
        /// Where "column" is a column in the virtual table, OP is an operator
        /// like "=" or "&lt;", and EXPR is an arbitrary expression. So, for
        /// example, if the WHERE clause contained a term like this:
        /// </para>
        /// <code>
        ///          a = 5
        /// </code>
        /// <para>
        /// Then one of the constraints would be on the "a" column with
        /// operator "=" and an expression of "5". Constraints need not have a
        /// literal representation of the WHERE clause. The query optimizer
        /// might make transformations to the WHERE clause in order to extract

        /// as many constraints as it can. So, for example, if the WHERE clause
        /// contained something like this:
        /// </para>
        /// <code>
        ///          x BETWEEN 10 AND 100 AND 999&gt;y
        /// </code>
        /// <para>
        /// The query optimizer might translate this into three separate
        /// constraints:
        /// </para>
        /// <code>
        ///          x &gt;= 10
        ///          x &lt;= 100
        ///          y &lt; 999
        /// </code>
        /// <para>
        /// For each constraint, the aConstraint[].iColumn field indicates
        /// which column appears on the left-hand side of the constraint. The
        /// first column of the virtual table is column 0. The rowid of the

        /// virtual table is column -1. The aConstraint[].op field indicates
        /// which operator is used. The SQLITE_INDEX_CONSTRAINT_* constants map
        /// integer constants into operator values. Columns occur in the order
        /// they were defined by the call to sqlite3_declare_vtab() in the
        /// xCreate or xConnect method. Hidden columns are counted when
        /// determining the column index.
        /// </para>
        /// <para>
        /// The aConstraint[] array contains information about all constraints
        /// that apply to the virtual table. But some of the constraints might
        /// not be usable because of the way tables are ordered in a join. The
        /// xBestIndex method must therefore only consider constraints that
        /// have an aConstraint[].usable flag which is true.
        /// </para>
        /// <para>
        /// In addition to WHERE clause constraints, the SQLite core also tells
        /// the xBestIndex method about the ORDER BY clause. (In an aggregate
        /// query, the SQLite core might put in GROUP BY clause information in
        /// place of the ORDER BY clause information, but this fact should not
        /// make any difference to the xBestIndex method.) If all terms of the
        /// ORDER BY clause are columns in the virtual table, then nOrderBy
        /// will be the number of terms in the ORDER BY clause and the
        /// aOrderBy[] array will identify the column for each term in the
        /// order by clause and whether or not that column is ASC or DESC.
        /// </para>
        /// <para>
        /// 2.3.2 Outputs
        /// </para>
        /// <para>
        /// Given all of the information above, the job of the xBestIndex
        /// method it to figure out the best way to search the virtual table.
        /// </para>
        /// <para>
        /// The xBestIndex method fills the idxNum and idxStr fields with
        /// information that communicates an indexing strategy to the xFilter
        /// method. The information in idxNum and idxStr is arbitrary as far as
        /// the SQLite core is concerned. The SQLite core just copies the
        /// information through to the xFilter method. Any desired meaning can
        /// be assigned to idxNum and idxStr as long as xBestIndex and xFilter
        /// agree on what that meaning is.
        /// </para>
        /// <para>
        /// The idxStr value may be a string obtained from an SQLite memory
        /// allocation function such as sqlite3_mprintf(). If this is the case,
        /// then the needToFreeIdxStr flag must be set to true so that the
        /// SQLite core will know to call sqlite3_free() on that string when it
        /// has finished with it, and thus avoid a memory leak.
        /// </para>
        /// <para>
        /// If the virtual table will output rows in the order specified by the
        /// ORDER BY clause, then the orderByConsumed flag may be set to true.
        /// If the output is not automatically in the correct order then
        /// orderByConsumed must be left in its default false setting. This
        /// will indicate to the SQLite core that it will need to do a separate
        /// sorting pass over the data after it comes out of the virtual table.
        /// </para>
        /// <para>
        /// The estimatedCost field should be set to the estimated number of
        /// disk access operations required to execute this query against the
        /// virtual table. The SQLite core will often call xBestIndex multiple
        /// times with different constraints, obtain multiple cost estimates,
        /// then choose the query plan that gives the lowest estimate.
        /// </para>
        /// <para>












        /// The aConstraintUsage[] array contains one element for each of the
        /// nConstraint constraints in the inputs section of the
        /// sqlite3_index_info structure. The aConstraintUsage[] array is used

        /// by xBestIndex to tell the core how it is using the constraints.
        /// </para>
        /// <para>
        /// The xBestIndex method may set aConstraintUsage[].argvIndex entries

        /// to values greater than one. Exactly one entry should be set to 1,
        /// another to 2, another to 3, and so forth up to as many or as few as
        /// the xBestIndex method wants. The EXPR of the corresponding
        /// constraints will then be passed in as the argv[] parameters to
        /// xFilter.
        /// </para>
        /// <para>
        /// For example, if the aConstraint[3].argvIndex is set to 1, then when
        /// xFilter is called, the argv[0] passed to xFilter will have the EXPR
        /// value of the aConstraint[3] constraint.
        /// </para>
        /// <para>
        /// By default, the SQLite core double checks all constraints on each
        /// row of the virtual table that it receives. If such a check is
        /// redundant, the xBestFilter method can suppress that double-check by
        /// setting aConstraintUsage[].omit.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="pIndex">
................................................................................
            IntPtr pVtab,
            IntPtr pIndex
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// This method releases a connection to a virtual table. Only the
        /// sqlite3_vtab object is destroyed. The virtual table is not

        /// destroyed and any backing store associated with the virtual table
        /// persists. This method undoes the work of xConnect.
        /// </para>

        /// <para>
        /// This method is a destructor for a connection to the virtual table.
        /// Contrast this method with xDestroy. The xDestroy is a destructor
        /// for the entire virtual table.
        /// </para>
        /// <para>
        /// The xDisconnect method is required for every virtual table
        /// implementation, though it is acceptable for the xDisconnect and
        /// xDestroy methods to be the same function if that makes sense for
        /// the particular virtual table.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xDisconnect(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// This method releases a connection to a virtual table, just like the
        /// xDisconnect method, and it also destroys the underlying table
        /// implementation. This method undoes the work of xCreate.
        /// </para>
        /// <para>
        /// The xDisconnect method is called whenever a database connection
        /// that uses a virtual table is closed. The xDestroy method is only
        /// called when a DROP TABLE statement is executed against the virtual
        /// table.
        /// </para>
        /// <para>
        /// The xDestroy method is required for every virtual table
        /// implementation, though it is acceptable for the xDisconnect and
        /// xDestroy methods to be the same function if that makes sense for
        /// the particular virtual table.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xDestroy(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// The xOpen method creates a new cursor used for accessing (read
        /// and/or writing) a virtual table. A successful invocation of this
        /// method will allocate the memory for the sqlite3_vtab_cursor (or a
        /// subclass), initialize the new object, and make *ppCursor point to
        /// the new object. The successful call then returns SQLITE_OK.
        /// </para>
        /// <para>
        /// For every successful call to this method, the SQLite core will
        /// later invoke the xClose method to destroy the allocated cursor.

        /// </para>
        /// <para>
        /// The xOpen method need not initialize the pVtab field of the
        /// sqlite3_vtab_cursor structure. The SQLite core will take care of
        /// that chore automatically.
        /// </para>
        /// <para>
        /// A virtual table implementation must be able to support an arbitrary
        /// number of simultaneously open cursors.
        /// </para>
        /// <para>
        /// When initially opened, the cursor is in an undefined state. The
        /// SQLite core will invoke the xFilter method on the cursor prior to
        /// any attempt to position or read from the cursor.
        /// </para>
        /// <para>
        /// The xOpen method is required for every virtual table
        /// implementation.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="pCursor">
        /// Upon success, this parameter must be modified to point to the newly
................................................................................
            IntPtr pVtab,
            ref IntPtr pCursor
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// The xClose method closes a cursor previously opened by xOpen. The

        /// SQLite core will always call xClose once for each cursor opened
        /// using xOpen.
        /// </para>
        /// <para>
        /// This method must release all resources allocated by the
        /// corresponding xOpen call. The routine will not be called again even
        /// if it returns an error. The SQLite core will not use the
        /// sqlite3_vtab_cursor again after it has been closed.
        /// </para>
        /// <para>
        /// The xClose method is required for every virtual table
        /// implementation.
        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xClose(
            IntPtr pCursor
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>




        /// <para>
        /// This method begins a search of a virtual table. The first argument
        /// is a cursor opened by xOpen. The next two argument define a
        /// particular search index previously chosen by xBestIndex. The
        /// specific meanings of idxNum and idxStr are unimportant as long as
        /// xFilter and xBestIndex agree on what that meaning is.

        /// </para>
        /// <para>
        /// The xBestIndex function may have requested the values of certain
        /// expressions using the aConstraintUsage[].argvIndex values of the
        /// sqlite3_index_info structure. Those values are passed to xFilter
        /// using the argc and argv parameters.
        /// </para>
        /// <para>
        /// If the virtual table contains one or more rows that match the
        /// search criteria, then the cursor must be left point at the first
        /// row. Subsequent calls to xEof must return false (zero). If there
        /// are no rows match, then the cursor must be left in a state that
        /// will cause the xEof to return true (non-zero). The SQLite engine

        /// will use the xColumn and xRowid methods to access that row content.
        /// The xNext method will be used to advance to the next row.
        /// </para>
        /// <para>
        /// This method must return SQLITE_OK if successful, or an sqlite error
        /// code if an error occurs.
        /// </para>
        /// <para>
        /// The xFilter method is required for every virtual table
        /// implementation.
        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <param name="idxNum">
        /// Number used to help identify the selected index.
................................................................................
            int argc,
            IntPtr argv
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// The xNext method advances a virtual table cursor to the next row of
        /// a result set initiated by xFilter. If the cursor is already
        /// pointing at the last row when this routine is called, then the
        /// cursor no longer points to valid data and a subsequent call to the

        /// xEof method must return true (non-zero). If the cursor is
        /// successfully advanced to another row of content, then subsequent
        /// calls to xEof must return false (zero).
        /// </para>
        /// <para>
        /// This method must return SQLITE_OK if successful, or an sqlite error
        /// code if an error occurs.
        /// </para>
        /// <para>
        /// The xNext method is required for every virtual table
        /// implementation.
        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xNext(
            IntPtr pCursor
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// The xEof method must return false (zero) if the specified cursor
        /// currently points to a valid row of data, or true (non-zero)
        /// otherwise. This method is called by the SQL engine immediately
        /// after each xFilter and xNext invocation.
        /// </para>
        /// <para>
        /// The xEof method is required for every virtual table implementation.
        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
................................................................................
        int xEof(
            IntPtr pCursor
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// The SQLite core invokes this method in order to find the value for
        /// the N-th column of the current row. N is zero-based so the first

        /// column is numbered 0. The xColumn method may return its result back
        /// to SQLite using one of the following interface:
        /// </para>
        /// <code>
        ///     sqlite3_result_blob()
        ///     sqlite3_result_double()
        ///     sqlite3_result_int()
        ///     sqlite3_result_int64()
        ///     sqlite3_result_null()
        ///     sqlite3_result_text()
        ///     sqlite3_result_text16()
        ///     sqlite3_result_text16le()
        ///     sqlite3_result_text16be()
        ///     sqlite3_result_zeroblob()
        /// </code>
        /// <para>
        /// If the xColumn method implementation calls none of the functions
        /// above, then the value of the column defaults to an SQL NULL.
        /// </para>
        /// <para>
        /// To raise an error, the xColumn method should use one of the
        /// result_text() methods to set the error message text, then return an
        /// appropriate error code. The xColumn method must return SQLITE_OK on
        /// success.
        /// </para>
        /// <para>
        /// The xColumn method is required for every virtual table
        /// implementation.
        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <param name="pContext">
        /// The native pointer to the sqlite3_context structure to be used
................................................................................
            IntPtr pContext,
            int index
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// A successful invocation of this method will cause *pRowid to be
        /// filled with the rowid of row that the virtual table cursor pCur is

        /// currently pointing at. This method returns SQLITE_OK on success. It
        /// returns an appropriate error code on failure.
        /// </para>
        /// <para>
        /// The xRowid method is required for every virtual table
        /// implementation.
        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <param name="rowId">
        /// Upon success, this parameter must be modified to contain the unique
................................................................................
            IntPtr pCursor,
            ref long rowId
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>








        /// <para>
        /// All changes to a virtual table are made using the xUpdate method.
        /// This one method can be used to insert, delete, or update.
        /// </para>
        /// <para>
        /// The argc parameter specifies the number of entries in the argv
        /// array. The value of argc will be 1 for a pure delete operation or
        /// N+2 for an insert or replace or update where N is the number of
        /// columns in the table. In the previous sentence, N includes any
        /// hidden columns.
        /// </para>
        /// <para>
        /// Every argv entry will have a non-NULL value in C but may contain
        /// the SQL value NULL. In other words, it is always true that

        /// argv[i]!=0 for i between 0 and argc-1. However, it might be the
        /// case that sqlite3_value_type(argv[i])==SQLITE_NULL.
        /// </para>
        /// <para>
        /// The argv[0] parameter is the rowid of a row in the virtual table
        /// to be deleted. If argv[0] is an SQL NULL, then no deletion occurs.
        /// </para>
        /// <para>
        /// The argv[1] parameter is the rowid of a new row to be inserted into
        /// the virtual table. If argv[1] is an SQL NULL, then the
        /// implementation must choose a rowid for the newly inserted row.
        /// Subsequent argv[] entries contain values of the columns of the
        /// virtual table, in the order that the columns were declared. The
        /// number of columns will match the table declaration that the
        /// xConnect or xCreate method made using the sqlite3_declare_vtab()
        /// call. All hidden columns are included.
        /// </para>
        /// <para>
        /// When doing an insert without a rowid (argc>1, argv[1] is an SQL
        /// NULL), the implementation must set *pRowid to the rowid of the
        /// newly inserted row; this will become the value returned by the
        /// sqlite3_last_insert_rowid() function. Setting this value in all the
        /// other cases is a harmless no-op; the SQLite engine ignores the
        /// *pRowid return value if argc==1 or argv[1] is not an SQL NULL.
        /// </para>
        /// <para>
        /// Each call to xUpdate will fall into one of cases shown below. Note
        /// that references to argv[i] mean the SQL value held within the
        /// argv[i] object, not the argv[i] object itself.

        /// </para>
        /// <code>
        ///     argc = 1
        /// </code>
        /// <para>
        ///         The single row with rowid equal to argv[0] is deleted. No
        ///         insert occurs.
        /// </para>
        /// <code>
        ///     argc > 1
        ///     argv[0] = NULL
        /// </code>
        /// <para>
        ///         A new row is inserted with a rowid argv[1] and column
        ///         values in argv[2] and following. If argv[1] is an SQL NULL,
        ///         the a new unique rowid is generated automatically.
        /// </para>
        /// <code>
        ///     argc > 1
        ///     argv[0] ? NULL
        ///     argv[0] = argv[1]
        /// </code>
        /// <para>
        ///         The row with rowid argv[0] is updated with new values in
        ///         argv[2] and following parameters.
        /// </para>
        /// <code>
        ///     argc > 1
        ///     argv[0] ? NULL
        ///     argv[0] ? argv[1]
        /// </code>
        /// <para>
        ///         The row with rowid argv[0] is updated with rowid argv[1]
        ///         and new values in argv[2] and following parameters. This
        ///         will occur when an SQL statement updates a rowid, as in
        ///         the statement:
        /// </para>
        /// <code>
        ///             UPDATE table SET rowid=rowid+1 WHERE ...;
        /// </code>

        /// <para>
        /// The xUpdate method must return SQLITE_OK if and only if it is
        /// successful. If a failure occurs, the xUpdate must return an
        /// appropriate error code. On a failure, the pVTab->zErrMsg element
        /// may optionally be replaced with error message text stored in memory
        /// allocated from SQLite using functions such as sqlite3_mprintf() or
        /// sqlite3_malloc().
        /// </para>
        /// <para>
        /// If the xUpdate method violates some constraint of the virtual table
        /// (including, but not limited to, attempting to store a value of the
        /// wrong datatype, attempting to store a value that is too large or
        /// too small, or attempting to change a read-only value) then the
        /// xUpdate must fail with an appropriate error code.
        /// </para>
        /// <para>
        /// There might be one or more sqlite3_vtab_cursor objects open and in
        /// use on the virtual table instance and perhaps even on the row of
        /// the virtual table when the xUpdate method is invoked. The
        /// implementation of xUpdate must be prepared for attempts to delete
        /// or modify rows of the table out from other existing cursors. If the
        /// virtual table cannot accommodate such changes, the xUpdate method
        /// must return an error code.
        /// </para>
        /// <para>
        /// The xUpdate method is optional. If the xUpdate pointer in the
        /// sqlite3_module for a virtual table is a NULL pointer, then the
        /// virtual table is read-only.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="argc">
        /// The number of new or modified column values contained in
................................................................................
            IntPtr argv,
            ref long rowId
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// This method begins a transaction on a virtual table. This is method
        /// is optional. The xBegin pointer of sqlite3_module may be NULL.

        /// </para>
        /// <para>
        /// This method is always followed by one call to either the xCommit or
        /// xRollback method. Virtual table transactions do not nest, so the
        /// xBegin method will not be invoked more than once on a single

        /// virtual table without an intervening call to either xCommit or
        /// xRollback. Multiple calls to other methods can and likely will
        /// occur in between the xBegin and the corresponding xCommit or
        /// xRollback.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xBegin(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// This method signals the start of a two-phase commit on a virtual

        /// table. This is method is optional. The xSync pointer of
        /// sqlite3_module may be NULL.
        /// </para>
        /// <para>
        /// This method is only invoked after call to the xBegin method and
        /// prior to an xCommit or xRollback. In order to implement two-phase
        /// commit, the xSync method on all virtual tables is invoked prior to
        /// invoking the xCommit method on any virtual table. If any of the
        /// xSync methods fail, the entire transaction is rolled back.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <returns>
................................................................................
        SQLiteErrorCode xSync(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// This method causes a virtual table transaction to commit. This is
        /// method is optional. The xCommit pointer of sqlite3_module may be
        /// NULL.

        /// </para>
        /// <para>
        /// A call to this method always follows a prior call to xBegin and
        /// xSync.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
................................................................................
        SQLiteErrorCode xCommit(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// This method causes a virtual table transaction to rollback. This is
        /// method is optional. The xRollback pointer of sqlite3_module may be
        /// NULL.

        /// </para>
        /// <para>
        /// A call to this method always follows a prior call to xBegin.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
................................................................................
        SQLiteErrorCode xRollback(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para>
        /// This method provides notification that the virtual table
        /// implementation that the virtual table will be given a new name. If
        /// this method returns SQLITE_OK then SQLite renames the table. If
        /// this method returns an error code then the renaming is prevented.








        /// </para>
        /// <para>
        /// The xRename method is required for every virtual table
        /// implementation.



















        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="nArg">
        /// The number of arguments to the function being sought.
................................................................................
            ref SQLiteCallback callback,
            ref IntPtr pClientData
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>



        /// <para>
        /// This method provides notification that the virtual table
        /// implementation that the virtual table will be given a new name. If
        /// this method returns SQLITE_OK then SQLite renames the table. If
        /// this method returns an error code then the renaming is prevented.
        /// </para>
        /// <para>
        /// The xRename method is required for every virtual table
        /// implementation.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="zNew">
        /// The native pointer to the UTF-8 encoded string containing the new
................................................................................
            IntPtr pVtab,
            IntPtr zNew
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>





        /// <para>
        /// These methods provide the virtual table implementation an
        /// opportunity to implement nested transactions. They are always
        /// optional and will only be called in SQLite version 3.7.7 and later.
        /// </para>
        /// <para>
        /// When xSavepoint(X,N) is invoked, that is a signal to the virtual
        /// table X that it should save its current state as savepoint N. A

        /// subsequent call to xRollbackTo(X,R) means that the state of the
        /// virtual table should return to what it was when xSavepoint(X,R) was

        /// last called. The call to xRollbackTo(X,R) will invalidate all
        /// savepoints with N>R; none of the invalided savepoints will be
        /// rolled back or released without first being reinitialized by a call
        /// to xSavepoint(). A call to xRelease(X,M) invalidates all savepoints
        /// where N>=M.
        /// </para>
        /// <para>
        /// None of the xSavepoint(), xRelease(), or xRollbackTo() methods will
        /// ever be called except in between calls to xBegin() and either
        /// xCommit() or xRollback().
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="iSavepoint">
        /// This is an integer identifier under which the the current state of
................................................................................
            IntPtr pVtab,
            int iSavepoint
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>





        /// <para>
        /// These methods provide the virtual table implementation an
        /// opportunity to implement nested transactions. They are always
        /// optional and will only be called in SQLite version 3.7.7 and later.
        /// </para>
        /// <para>
        /// When xSavepoint(X,N) is invoked, that is a signal to the virtual
        /// table X that it should save its current state as savepoint N. A

        /// subsequent call to xRollbackTo(X,R) means that the state of the
        /// virtual table should return to what it was when xSavepoint(X,R) was

        /// last called. The call to xRollbackTo(X,R) will invalidate all
        /// savepoints with N>R; none of the invalided savepoints will be
        /// rolled back or released without first being reinitialized by a call
        /// to xSavepoint(). A call to xRelease(X,M) invalidates all savepoints
        /// where N>=M.
        /// </para>
        /// <para>
        /// None of the xSavepoint(), xRelease(), or xRollbackTo() methods will
        /// ever be called except in between calls to xBegin() and either
        /// xCommit() or xRollback().
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="iSavepoint">
        /// This is an integer used to indicate that any saved states with an
................................................................................
            IntPtr pVtab,
            int iSavepoint
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>





        /// <para>
        /// These methods provide the virtual table implementation an
        /// opportunity to implement nested transactions. They are always
        /// optional and will only be called in SQLite version 3.7.7 and later.
        /// </para>
        /// <para>
        /// When xSavepoint(X,N) is invoked, that is a signal to the virtual
        /// table X that it should save its current state as savepoint N. A

        /// subsequent call to xRollbackTo(X,R) means that the state of the
        /// virtual table should return to what it was when xSavepoint(X,R) was

        /// last called. The call to xRollbackTo(X,R) will invalidate all
        /// savepoints with N>R; none of the invalided savepoints will be
        /// rolled back or released without first being reinitialized by a call
        /// to xSavepoint(). A call to xRelease(X,M) invalidates all savepoints
        /// where N>=M.
        /// </para>
        /// <para>
        /// None of the xSavepoint(), xRelease(), or xRollbackTo() methods will
        /// ever be called except in between calls to xBegin() and either
        /// xCommit() or xRollback().
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="iSavepoint">
        /// This is an integer identifier used to specify a specific saved
        /// state for the virtual table for it to restore itself back to, which
        /// should also have the effect of deleting all saved states with an
        /// integer identifier greater than this one.
        /// <list type=""></list>
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
        /// </returns>
        SQLiteErrorCode xRollbackTo(
            IntPtr pVtab,
            int iSavepoint
            );
    }
    #endregion
}







>
>
>
>
>
>

|
|
|
|
|
>
|
|
|
|
|
|
|
|
<
|
|
<
|
|
|
|






|
|
|
|

|
<
|
|
<

|

|
|
|
|
|
|
|
|
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>







 







>
>
>
>
>
>

|
|
>
|


|
|




|
|
|
|
>


|

|
|
|
|


|
|
|
|
|
<


|
|
|
|
>
|
|





|
|
|
|







 







|
|
|

|
|
|

|
|
|
|
|
<

|
|
|
|
|
|
<
|
|
|
<
|
|
<
|
|
|
|
|
|
<
<
>
|
<
|
|
<
<
>
|
<
|
|
>
>
>
>
|
|

>
>
>
>
>
>
>
>
>


|
|
|
|
|
|
|
>
|

|
|
|
|
|
|
|
|
|


|
|
|
|


|

|
|
|
|
|
|



|
|
|
|
|
<



|
|
|


|
<


<
<
<
|
|
|
|



|
|

|
|
|

|
|
|

|
|
|

|

|
|
>
|
|

|
|
|

|
<

|
|
|
|
|

|
|
|
>
|
|
|
|
|
|


|

|
|
|


|
|
|
|
|
|
|
|
|


<
<
<
|



|
|
|
|
|
|



|
|
|
|
|


|
|
|
|
|
|


|
|
|
|
|


>
>
>
>
>
>
>
>
>
>
>
>
|
|
|
>
|


|
>
|
|
|
|
<


|
|
|


|
|
|







 







>
>
>

|
|
>
|
<

>


|



|
|
|
<







 







>
>
>

|
|
|



|
|
<


|
|
|
<







 







>
>
>

|
|
|
|
|



|
>



|
|






|
|
|


|
<







 







>
>
>

|
>
|




|
|



|
<







 







>
>
>
>

|
|
|
|
|
>


|
|
|
|



|
|
|
|
>
|



|
|


|
<







 







>
>
>

|
|
|
<
>
|
|
|


|
|


|
<







 







>
>
>

|
|
|
|







 







>
>
>

|
|
>
|
|

|
|
|
|
|
|
|
|
|
|
|
|

|
|


|
|
|
<


|
<







 







>
>
>


|
>
|
|


|
<







 







>
>
>
>
>
>
>
>





|
|
|
|
<


|
|
>
|
|


|



|
|
|
|
|
|
<
|


|
|
|
|
|
|


|
|
|
>

|
|
<
<
|
<
<
<
|
|
<
<
|
|
|
<
<
|
|
|
<
<
|
|
<
<
|
|
|
<
<
|
|
|
<
|
<
|
|
>


|
|
|
|
<



|
|
|



|
|
|
|
|
|
<


|
|
|







 







>
>
>

|
|
>


|
|
|
>
|
|
|
<







 







>
>
>


>
|
|



|

|







 







>
>
>

|
|
<
>







 







>
>
>

|
|
<
>







 







|
|
|
|
|
>
>
>
>
>
>
>
>


<
<
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>







 







>
>
>

|
|
|
|


|
<







 







>
>
>
>
>

|
|
|


|
|
>
|
|
>
|
|
|
|
<


|
|
|







 







>
>
>
>
>

|
|
|


|
|
>
|
|
>
|
|
|
|
<


|
|
|







 







>
>
>
>
>

|
|
|


|
|
>
|
|
>
|
|
|
|
<


|
|
|










<











11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

39
40

41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56

57
58

59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
...
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256

257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
...
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329

330
331
332
333
334
335
336

337
338
339

340
341

342
343
344
345
346
347


348
349

350
351


352
353

354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416

417
418
419
420
421
422
423
424
425

426
427



428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462

463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499



500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559

560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
...
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597

598
599
600
601
602
603
604
605
606
607
608

609
610
611
612
613
614
615
...
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635

636
637
638
639
640

641
642
643
644
645
646
647
...
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686

687
688
689
690
691
692
693
...
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723

724
725
726
727
728
729
730
...
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772

773
774
775
776
777
778
779
...
800
801
802
803
804
805
806
807
808
809
810
811
812
813

814
815
816
817
818
819
820
821
822
823
824

825
826
827
828
829
830
831
...
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
...
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895

896
897
898

899
900
901
902
903
904
905
...
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936

937
938
939
940
941
942
943
...
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973

974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992

993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010


1011



1012
1013


1014
1015
1016


1017
1018
1019


1020
1021


1022
1023
1024


1025
1026
1027

1028

1029
1030
1031
1032
1033
1034
1035
1036
1037

1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052

1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
....
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103

1104
1105
1106
1107
1108
1109
1110
....
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
....
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154

1155
1156
1157
1158
1159
1160
1161
1162
....
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180

1181
1182
1183
1184
1185
1186
1187
1188
....
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214


1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
....
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278

1279
1280
1281
1282
1283
1284
1285
....
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319

1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
....
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365

1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
....
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412

1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427

1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
    /// <summary>
    /// This interface represents a virtual table implementation written in
    /// native code.
    /// </summary>
    public interface ISQLiteNativeModule
    {
        /// <summary>
        /// <para><code>
        ///   int (*xCreate)(sqlite3 *db, void *pAux,
        ///                int argc, char **argv,
        ///                sqlite3_vtab **ppVTab,
        ///                char **pzErr);
        /// </code></para>
        /// <para>
        /// This method is called to create a new instance of a virtual table 
        /// in response to a CREATE VIRTUAL TABLE statement. 
        /// The db parameter is a pointer to the SQLite database connection that 
        /// is executing the CREATE VIRTUAL TABLE statement. 
        /// The pAux argument is the copy of the client data pointer that was the 
        /// fourth argument to the sqlite3_create_module() or
        /// sqlite3_create_module_v2() call that registered the 
        /// virtual table module. 
        /// The argv parameter is an array of argc pointers to null terminated strings. 
        /// The first string, argv[0], is the name of the module being invoked.   The
        /// module name is the name provided as the second argument to 
        /// sqlite3_create_module() and as the argument to the USING clause of the
        /// CREATE VIRTUAL TABLE statement that is running.
        /// The second, argv[1], is the name of the database in which the new virtual table is being created. The database name is "main" for the primary database, or

        /// "temp" for TEMP database, or the name given at the end of the ATTACH
        /// statement for attached databases.  The third element of the array, argv[2], 

        /// is the name of the new virtual table, as specified following the TABLE
        /// keyword in the CREATE VIRTUAL TABLE statement.
        /// If present, the fourth and subsequent strings in the argv[] array report 
        /// the arguments to the module name in the CREATE VIRTUAL TABLE statement.
        /// </para>
        /// <para>
        /// The job of this method is to construct the new virtual table object
        /// (an sqlite3_vtab object) and return a pointer to it in *ppVTab.
        /// </para>
        /// <para>
        /// As part of the task of creating a new sqlite3_vtab structure, this 
        /// method <u>must</u> invoke sqlite3_declare_vtab() to tell the SQLite 
        /// core about the columns and datatypes in the virtual table. 
        /// The sqlite3_declare_vtab() API has the following prototype:
        /// </para>
        /// <para><code>

        ///     int sqlite3_declare_vtab(sqlite3 *db, const char *zCreateTable)
        /// </code></para>

        /// <para>
        /// The first argument to sqlite3_declare_vtab() must be the same 
        /// database connection pointer as the first parameter to this method.
        /// The second argument to sqlite3_declare_vtab() must a zero-terminated 
        /// UTF-8 string that contains a well-formed CREATE TABLE statement that 
        /// defines the columns in the virtual table and their data types. 
        /// The name of the table in this CREATE TABLE statement is ignored, 
        /// as are all constraints. Only the column names and datatypes matter.
        /// The CREATE TABLE statement string need not to be 
        /// held in persistent memory.  The string can be
        /// deallocated and/or reused as soon as the sqlite3_declare_vtab()
        /// routine returns.
        /// </para>
        /// <para>
        /// The xCreate method need not initialize the pModule, nRef, and zErrMsg
        /// fields of the sqlite3_vtab object.  The SQLite core will take care of 
        /// that chore.
        /// </para>
        /// <para>
        /// The xCreate should return SQLITE_OK if it is successful in 
        /// creating the new virtual table, or SQLITE_ERROR if it is not successful.
        /// If not successful, the sqlite3_vtab structure must not be allocated. 
        /// An error message may optionally be returned in *pzErr if unsuccessful.
        /// Space to hold the error message string must be allocated using
        /// an SQLite memory allocation function like 
        /// sqlite3_malloc() or sqlite3_mprintf() as the SQLite core will
        /// attempt to free the space using sqlite3_free() after the error has
        /// been reported up to the application.
        /// </para>
        /// <para>
        /// If the xCreate method is omitted (left as a NULL pointer) then the
        /// virtual table is an eponymous-only virtual table.  New instances of
        /// the virtual table cannot be created using CREATE VIRTUAL TABLE and the
        /// virtual table can only be used via its module name.
        /// Note that SQLite versions prior to 3.9.0 do not understand
        /// eponymous-only virtual tables and will segfault if an attempt is made
        /// to CREATE VIRTUAL TABLE on an eponymous-only virtual table because
        /// the xCreate method was not checked for null.
        /// </para>
        /// <para>
        /// If the xCreate method is the exact same pointer as the xConnect method,
        /// that indicates that the virtual table does not need to initialize backing
        /// store.  Such a virtual table can be used as an eponymous virtual table
        /// or as a named virtual table using CREATE VIRTUAL TABLE or both.
        /// </para>
        /// <para>
        /// If a column datatype contains the special keyword "HIDDEN"
        /// (in any combination of upper and lower case letters) then that keyword
        /// it is omitted from the column datatype name and the column is marked 
        /// as a hidden column internally. 
        /// A hidden column differs from a normal column in three respects:
        /// </para>
        /// <para>
        ///  Hidden columns are not listed in the dataset returned by 
        ///      "PRAGMA table_info",
        ///  Hidden columns are not included in the expansion of a "*"
        ///      expression in the result set of a SELECT, and
        ///  Hidden columns are not included in the implicit column-list 
        ///      used by an INSERT statement that lacks an explicit column-list. 
        /// </para>
        /// <para>
        /// For example, if the following SQL is passed to sqlite3_declare_vtab():
        /// </para>
        /// <para><code>
        ///    CREATE TABLE x(a HIDDEN VARCHAR(12), b INTEGER, c INTEGER Hidden);
        /// </code></para>
        /// <para>
        /// Then the virtual table would be created with two hidden columns,
        /// and with datatypes of "VARCHAR(12)" and "INTEGER".
        /// </para>
        /// <para>
        /// An example use of hidden columns can be seen in the FTS3 virtual 
        /// table implementation, where every FTS virtual table
        /// contains an FTS hidden column that is used to pass information from the
        /// virtual table into FTS auxiliary functions and to the FTS MATCH operator.
        /// </para>
        /// <para>
        /// A virtual table that contains hidden columns can be used like
        /// a table-valued function in the FROM clause of a SELECT statement.
        /// The arguments to the table-valued function become constraints on 
        /// the HIDDEN columns of the virtual table.
        /// </para>
        /// <para>
        /// For example, the "generate_series" extension (located in the
        /// ext/misc/series.c
        /// file in the source tree)
        /// implements an eponymous virtual table with the following schema:
        /// </para>
        /// <para><code>
        /// CREATE TABLE generate_series(
        ///   value,
        ///   start HIDDEN,
        ///   stop HIDDEN,
        ///   step HIDDEN
        /// );
        /// </code></para>
        /// <para>
        /// The sqlite3_module.xBestIndex method in the implementation of this
        /// table checks for equality constraints against the HIDDEN columns, and uses
        /// those as input parameters to determine the range of integer "value" outputs
        /// to generate.  Reasonable defaults are used for any unconstrained columns.
        /// For example, to list all integers between 5 and 50:
        /// </para>
        /// <para><code>
        /// SELECT value FROM generate_series(5,50);
        /// </code></para>
        /// <para>
        /// The previous query is equivalent to the following:
        /// </para>
        /// <para><code>
        /// SELECT value FROM generate_series WHERE start=5 AND stop=50;
        /// </code></para>
        /// <para>
        /// Arguments on the virtual table name are matched to hidden columns
        /// in order.  The number of arguments can be less than the
        /// number of hidden columns, in which case the latter hidden columns are
        /// unconstrained.  However, an error results if there are more arguments
        /// than there are hidden columns in the virtual table.
        /// </para>
        /// </summary>
        /// <param name="pDb">
        /// The native database connection handle.
        /// </param>
        /// <param name="pAux">
        /// The original native pointer value that was provided to the
................................................................................
            ref IntPtr pVtab,
            ref IntPtr pError
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xConnect)(sqlite3*, void *pAux,
        ///                int argc, char **argv,
        ///                sqlite3_vtab **ppVTab,
        ///                char **pzErr);
        /// </code></para>
        /// <para>
        /// The xConnect method is very similar to xCreate. 
        /// It has the same parameters and constructs a new sqlite3_vtab structure 
        /// just like xCreate. 
        /// And it must also call sqlite3_declare_vtab() like xCreate.
        /// </para>
        /// <para>
        /// The difference is that xConnect is called to establish a new 
        /// connection to an existing virtual table whereas xCreate is called 
        /// to create a new virtual table from scratch.
        /// </para>
        /// <para>
        /// The xCreate and xConnect methods are only different when the
        /// virtual table has some kind of backing store that must be initialized 
        /// the first time the virtual table is created. The xCreate method creates 
        /// and initializes the backing store. The xConnect method just connects 
        /// to an existing backing store.  When xCreate and xConnect are the same,
        /// the table is an eponymous virtual table.
        /// </para>
        /// <para>
        /// As an example, consider a virtual table implementation that 
        /// provides read-only access to existing comma-separated-value (CSV)
        /// files on disk. There is no backing store that needs to be created 
        /// or initialized for such a virtual table (since the CSV files already 
        /// exist on disk) so the xCreate and xConnect methods will be identical 
        /// for that module.
        /// </para>
        /// <para>
        /// Another example is a virtual table that implements a full-text index. 
        /// The xCreate method must create and initialize data structures to hold 
        /// the dictionary and posting lists for that index. The xConnect method,
        /// on the other hand, only has to locate and use an existing dictionary 
        /// and posting lists that were created by a prior xCreate call.

        /// </para>
        /// <para>
        /// The xConnect method must return SQLITE_OK if it is successful 
        /// in creating the new virtual table, or SQLITE_ERROR if it is not 
        /// successful. If not successful, the sqlite3_vtab structure must not be 
        /// allocated. An error message may optionally be returned in *pzErr if 
        /// unsuccessful. 
        /// Space to hold the error message string must be allocated using
        /// an SQLite memory allocation function like 
        /// sqlite3_malloc() or sqlite3_mprintf() as the SQLite core will
        /// attempt to free the space using sqlite3_free() after the error has
        /// been reported up to the application.
        /// </para>
        /// <para>
        /// The xConnect method is required for every virtual table implementation, 
        /// though the xCreate and xConnect pointers of the sqlite3_module object
        /// may point to the same function if the virtual table does not need to
        /// initialize backing store.
        /// </para>
        /// </summary>
        /// <param name="pDb">
        /// The native database connection handle.
        /// </param>
        /// <param name="pAux">
        /// The original native pointer value that was provided to the
................................................................................
            ref IntPtr pError
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para>
        /// SQLite uses the xBestIndex method of a virtual table module to determine
        /// the best way to access the virtual table. 
        /// The xBestIndex method has a prototype like this:
        /// </para>
        /// <para><code>
        ///   int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
        /// </code></para>
        /// <para>
        /// The SQLite core communicates with the xBestIndex method by filling 
        /// in certain fields of the sqlite3_index_info structure and passing a 
        /// pointer to that structure into xBestIndex as the second parameter. 
        /// The xBestIndex method fills out other fields of this structure which
        /// forms the reply. The sqlite3_index_info structure looks like this:

        /// </para>
        /// <para><code>
        ///   struct sqlite3_index_info {
        ///     /* Inputs */
        ///     const int nConstraint;     /* Number of entries in aConstraint */
        ///     const struct sqlite3_index_constraint {
        ///        int iColumn;              /* Column on left-hand side of constraint */

        ///        unsigned char op;         /* Constraint operator */
        ///        unsigned char usable;     /* True if this constraint is usable */
        ///        int iTermOffset;          /* Used internally - xBestIndex should ignore */

        ///     } *const aConstraint;      /* Table of WHERE clause constraints */
        ///     const int nOrderBy;        /* Number of terms in the ORDER BY clause */

        ///     const struct sqlite3_index_orderby {
        ///        int iColumn;              /* Column number */
        ///        unsigned char desc;       /* True for DESC.  False for ASC. */
        ///     } *const aOrderBy;         /* The ORDER BY clause */
        ///     /* Outputs */
        ///     struct sqlite3_index_constraint_usage {


        ///       int argvIndex;           /* if &gt;0, constraint is part of argv to xFilter */
        ///       unsigned char omit;      /* Do not code a test for this constraint */

        ///     } *const aConstraintUsage;
        ///     int idxNum;                /* Number used to identify the index */


        ///     char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
        ///     int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */

        ///     int orderByConsumed;       /* True if output is already ordered */
        ///     double estimatedCost;      /* Estimated cost of using this index */
        ///     /* Fields below are only available in SQLite 3.8.2 and later */
        ///     sqlite3_int64 estimatedRows;    /* Estimated number of rows returned */
        ///     /* Fields below are only available in SQLite 3.9.0 and later */
        ///     int idxFlags;              /* Mask of SQLITE_INDEX_SCAN_* flags */
        ///   };
        /// </code></para>
        /// <para>
        /// Please note the warnings on the "estimatedRows" and "idxFlags" field.
        /// These fields were added with SQLite versions 3.8.2 and 3.9.0, respectively. 
        /// Any extension that reads or writes these fields must first check that the 
        /// version of the SQLite library in use is greater than or equal to 3.8.2 or
        /// 3.9.0 - perhaps using a call to sqlite3_version(). The result of attempting 
        /// to access these fields in an sqlite3_index_info structure created by an 
        /// older version of SQLite are undefined.
        /// </para>
        /// <para>
        /// In addition, there are some defined constants:
        /// </para>
        /// <para><code>
        ///   #define SQLITE_INDEX_CONSTRAINT_EQ    2
        ///   #define SQLITE_INDEX_CONSTRAINT_GT    4
        ///   #define SQLITE_INDEX_CONSTRAINT_LE    8
        ///   #define SQLITE_INDEX_CONSTRAINT_LT    16
        ///   #define SQLITE_INDEX_CONSTRAINT_GE    32
        ///   #define SQLITE_INDEX_CONSTRAINT_MATCH 64
        ///   #define SQLITE_INDEX_SCAN_UNIQUE      1     /* Scan visits at most 1 row */
        /// </code></para>
        /// <para>
        /// The SQLite core calls the xBestIndex method when it is compiling a query
        /// that involves a virtual table. In other words, SQLite calls this method 
        /// when it is running sqlite3_prepare() or the equivalent. 
        /// By calling this method, the 
        /// SQLite core is saying to the virtual table that it needs to access 
        /// some subset of the rows in the virtual table and it wants to know the
        /// most efficient way to do that access. The xBestIndex method replies 
        /// with information that the SQLite core can then use to conduct an 
        /// efficient search of the virtual table.
        /// </para>
        /// <para>
        /// While compiling a single SQL query, the SQLite core might call 
        /// xBestIndex multiple times with different settings in sqlite3_index_info.
        /// The SQLite core will then select the combination that appears to 
        /// give the best performance.
        /// </para>
        /// <para>
        /// Before calling this method, the SQLite core initializes an instance 
        /// of the sqlite3_index_info structure with information about the
        /// query that it is currently trying to process. This information 
        /// derives mainly from the WHERE clause and ORDER BY or GROUP BY clauses 
        /// of the query, but also from any ON or USING clauses if the query is a 
        /// join. The information that the SQLite core provides to the xBestIndex 
        /// method is held in the part of the structure that is marked as "Inputs". 
        /// The "Outputs" section is initialized to zero.
        /// </para>
        /// <para>
        /// The information in the sqlite3_index_info structure is ephemeral
        /// and may be overwritten or deallocated as soon as the xBestIndex method
        /// returns.  If the xBestIndex method needs to remember any part of the
        /// sqlite3_index_info structure, it should make a copy.  Care must be
        /// take to store the copy in a place where it will be deallocated, such
        /// as in the idxStr field with needToFreeIdxStr set to 1.

        /// </para>
        /// <para>
        /// Note that xBestIndex will always be called before xFilter, since
        /// the idxNum and idxStr outputs from xBestIndex are required inputs to
        /// xFilter.  However, there is no guarantee that xFilter will be called
        /// following a successful xBestIndex.  
        /// </para>
        /// <para>
        /// The xBestIndex method is required for every virtual table implementation.

        /// </para>
        /// <para>



        /// The main thing that the SQLite core is trying to communicate to 
        /// the virtual table is the constraints that are available to limit 
        /// the number of rows that need to be searched. The aConstraint[] array 
        /// contains one entry for each constraint. There will be exactly 
        /// nConstraint entries in that array.
        /// </para>
        /// <para>
        /// Each constraint will correspond to a term in the WHERE clause
        /// or in a USING or ON clause that is of the form
        /// </para>
        /// <para><code>
        ///      column  OP  EXPR
        /// </code></para>
        /// <para>
        /// Where "column" is a column in the virtual table, OP is an operator 
        /// like "=" or "&lt;", and EXPR is an arbitrary expression. So, for example,
        /// if the WHERE clause contained a term like this:
        /// </para>
        /// <para><code>
        ///      a = 5
        /// </code></para>
        /// <para>
        /// Then one of the constraints would be on the "a" column with 
        /// operator "=" and an expression of "5". Constraints need not have a
        /// literal representation of the WHERE clause. The query optimizer might
        /// make transformations to the 
        /// WHERE clause in order to extract as many constraints 
        /// as it can. So, for example, if the WHERE clause contained something 
        /// like this:
        /// </para>
        /// <para><code>
        ///      x BETWEEN 10 AND 100 AND 999&gt;y
        /// </code></para>
        /// <para>
        /// The query optimizer might translate this into three separate constraints:

        /// </para>
        /// <para><code>
        ///      x &gt;= 10
        ///      x &lt;= 100
        ///      y &lt; 999
        /// </code></para>
        /// <para>
        /// For each constraint, the aConstraint[].iColumn field indicates which 
        /// column appears on the left-hand side of the constraint.
        /// The first column of the virtual table is column 0. 
        /// The rowid of the virtual table is column -1. 
        /// The aConstraint[].op field indicates which operator is used. 
        /// The SQLITE_INDEX_CONSTRAINT_* constants map integer constants 
        /// into operator values.
        /// Columns occur in the order they were defined by the call to
        /// sqlite3_declare_vtab() in the xCreate or xConnect method.
        /// Hidden columns are counted when determining the column index.
        /// </para>
        /// <para>
        /// The aConstraint[] array contains information about all constraints 
        /// that apply to the virtual table. But some of the constraints might
        /// not be usable because of the way tables are ordered in a join. 
        /// The xBestIndex method must therefore only consider constraints 
        /// that have an aConstraint[].usable flag which is true.
        /// </para>
        /// <para>
        /// In addition to WHERE clause constraints, the SQLite core also 
        /// tells the xBestIndex method about the ORDER BY clause. 
        /// (In an aggregate query, the SQLite core might put in GROUP BY clause 
        /// information in place of the ORDER BY clause information, but this fact
        /// should not make any difference to the xBestIndex method.) 
        /// If all terms of the ORDER BY clause are columns in the virtual table, 
        /// then nOrderBy will be the number of terms in the ORDER BY clause 
        /// and the aOrderBy[] array will identify the column for each term 
        /// in the order by clause and whether or not that column is ASC or DESC.
        /// </para>
        /// <para>



        /// Given all of the information above, the job of the xBestIndex 
        /// method it to figure out the best way to search the virtual table.
        /// </para>
        /// <para>
        /// The xBestIndex method fills the idxNum and idxStr fields with 
        /// information that communicates an indexing strategy to the xFilter 
        /// method. The information in idxNum and idxStr is arbitrary as far 
        /// as the SQLite core is concerned. The SQLite core just copies the 
        /// information through to the xFilter method. Any desired meaning can 
        /// be assigned to idxNum and idxStr as long as xBestIndex and xFilter 
        /// agree on what that meaning is.
        /// </para>
        /// <para>
        /// The idxStr value may be a string obtained from an SQLite
        /// memory allocation function such as sqlite3_mprintf(). 
        /// If this is the case, then the needToFreeIdxStr flag must be set to 
        /// true so that the SQLite core will know to call sqlite3_free() on 
        /// that string when it has finished with it, and thus avoid a memory leak.
        /// </para>
        /// <para>
        /// If the virtual table will output rows in the order specified by 
        /// the ORDER BY clause, then the orderByConsumed flag may be set to 
        /// true. If the output is not automatically in the correct order 
        /// then orderByConsumed must be left in its default false setting. 
        /// This will indicate to the SQLite core that it will need to do a 
        /// separate sorting pass over the data after it comes out of the virtual table.
        /// </para>
        /// <para>
        /// The estimatedCost field should be set to the estimated number
        /// of disk access operations required to execute this query against 
        /// the virtual table. The SQLite core will often call xBestIndex 
        /// multiple times with different constraints, obtain multiple cost
        /// estimates, then choose the query plan that gives the lowest estimate.
        /// </para>
        /// <para>
        /// If the current version of SQLite is 3.8.2 or greater, the estimatedRows
        /// field may be set to an estimate of the number of rows returned by the
        /// proposed query plan. If this value is not explicitly set, the default 
        /// estimate of 25 rows is used.
        /// </para>
        /// <para>
        /// If the current version of SQLite is 3.9.0 or greater, the idxFlags field
        /// may be set to SQLITE_INDEX_SCAN_UNIQUE to indicate that the virtual table
        /// will return only zero or one rows given the input constraints.  Additional
        /// bits of the idxFlags field might be understood in later versions of SQLite.
        /// </para>
        /// <para>
        /// The aConstraintUsage[] array contains one element for each of 
        /// the nConstraint constraints in the inputs section of the 
        /// sqlite3_index_info structure. 
        /// The aConstraintUsage[] array is used by xBestIndex to tell the 
        /// core how it is using the constraints.
        /// </para>
        /// <para>
        /// The xBestIndex method may set aConstraintUsage[].argvIndex 
        /// entries to values greater than zero. 
        /// Exactly one entry should be set to 1, another to 2, another to 3, 
        /// and so forth up to as many or as few as the xBestIndex method wants. 
        /// The EXPR of the corresponding constraints will then be passed 
        /// in as the argv[] parameters to xFilter.

        /// </para>
        /// <para>
        /// For example, if the aConstraint[3].argvIndex is set to 1, then 
        /// when xFilter is called, the argv[0] passed to xFilter will have 
        /// the EXPR value of the aConstraint[3] constraint.
        /// </para>
        /// <para>
        /// By default, the SQLite core double checks all constraints on 
        /// each row of the virtual table that it receives. If such a check 
        /// is redundant, the xBestFilter method can suppress that double-check by 
        /// setting aConstraintUsage[].omit.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="pIndex">
................................................................................
            IntPtr pVtab,
            IntPtr pIndex
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xDisconnect)(sqlite3_vtab *pVTab);
        /// </code></para>
        /// <para>
        /// This method releases a connection to a virtual table. 
        /// Only the sqlite3_vtab object is destroyed.
        /// The virtual table is not destroyed and any backing store 
        /// associated with the virtual table persists. 

        /// </para>
        /// This method undoes the work of xConnect.
        /// <para>
        /// This method is a destructor for a connection to the virtual table.
        /// Contrast this method with xDestroy.  The xDestroy is a destructor
        /// for the entire virtual table.
        /// </para>
        /// <para>
        /// The xDisconnect method is required for every virtual table implementation,
        /// though it is acceptable for the xDisconnect and xDestroy methods to be
        /// the same function if that makes sense for the particular virtual table.

        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xDisconnect(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xDestroy)(sqlite3_vtab *pVTab);
        /// </code></para>
        /// <para>
        /// This method releases a connection to a virtual table, just like 
        /// the xDisconnect method, and it also destroys the underlying 
        /// table implementation. This method undoes the work of xCreate.
        /// </para>
        /// <para>
        /// The xDisconnect method is called whenever a database connection
        /// that uses a virtual table is closed. The xDestroy method is only 
        /// called when a DROP TABLE statement is executed against the virtual table.

        /// </para>
        /// <para>
        /// The xDestroy method is required for every virtual table implementation,
        /// though it is acceptable for the xDisconnect and xDestroy methods to be
        /// the same function if that makes sense for the particular virtual table.

        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xDestroy(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
        /// </code></para>
        /// <para>
        /// The xOpen method creates a new cursor used for accessing (read and/or
        /// writing) a virtual table.  A successful invocation of this method 
        /// will allocate the memory for the sqlite3_vtab_cursor (or a subclass),
        /// initialize the new object, and make *ppCursor point to the new object.
        /// The successful call then returns SQLITE_OK.
        /// </para>
        /// <para>
        /// For every successful call to this method, the SQLite core will
        /// later invoke the xClose method to destroy 
        /// the allocated cursor.
        /// </para>
        /// <para>
        /// The xOpen method need not initialize the pVtab field of the
        /// sqlite3_vtab_cursor structure.  The SQLite core will take care
        /// of that chore automatically.
        /// </para>
        /// <para>
        /// A virtual table implementation must be able to support an arbitrary
        /// number of simultaneously open cursors.
        /// </para>
        /// <para>
        /// When initially opened, the cursor is in an undefined state.
        /// The SQLite core will invoke the xFilter method
        /// on the cursor prior to any attempt to position or read from the cursor.
        /// </para>
        /// <para>
        /// The xOpen method is required for every virtual table implementation.

        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="pCursor">
        /// Upon success, this parameter must be modified to point to the newly
................................................................................
            IntPtr pVtab,
            ref IntPtr pCursor
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xClose)(sqlite3_vtab_cursor*);
        /// </code></para>
        /// <para>
        /// The xClose method closes a cursor previously opened by 
        /// xOpen. 
        /// The SQLite core will always call xClose once for each cursor opened 
        /// using xOpen.
        /// </para>
        /// <para>
        /// This method must release all resources allocated by the
        /// corresponding xOpen call. The routine will not be called again even if it
        /// returns an error.  The SQLite core will not use the
        /// sqlite3_vtab_cursor again after it has been closed.
        /// </para>
        /// <para>
        /// The xClose method is required for every virtual table implementation.

        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xClose(
            IntPtr pCursor
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
        ///                 int argc, sqlite3_value **argv);
        /// </code></para>
        /// <para>
        /// This method begins a search of a virtual table. 
        /// The first argument is a cursor opened by xOpen. 
        /// The next two arguments define a particular search index previously 
        /// chosen by xBestIndex. The specific meanings of idxNum and idxStr 
        /// are unimportant as long as xFilter and xBestIndex agree on what 
        /// that meaning is.
        /// </para>
        /// <para>
        /// The xBestIndex function may have requested the values of 
        /// certain expressions using the aConstraintUsage[].argvIndex values 
        /// of the sqlite3_index_info structure. 
        /// Those values are passed to xFilter using the argc and argv parameters.
        /// </para>
        /// <para>
        /// If the virtual table contains one or more rows that match the
        /// search criteria, then the cursor must be left point at the first row.
        /// Subsequent calls to xEof must return false (zero).
        /// If there are no rows match, then the cursor must be left in a state 
        /// that will cause the xEof to return true (non-zero).
        /// The SQLite engine will use
        /// the xColumn and xRowid methods to access that row content.
        /// The xNext method will be used to advance to the next row.
        /// </para>
        /// <para>
        /// This method must return SQLITE_OK if successful, or an sqlite 
        /// error code if an error occurs.
        /// </para>
        /// <para>
        /// The xFilter method is required for every virtual table implementation.

        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <param name="idxNum">
        /// Number used to help identify the selected index.
................................................................................
            int argc,
            IntPtr argv
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xNext)(sqlite3_vtab_cursor*);
        /// </code></para>
        /// <para>
        /// The xNext method advances a virtual table cursor
        /// to the next row of a result set initiated by xFilter. 
        /// If the cursor is already pointing at the last row when this 

        /// routine is called, then the cursor no longer points to valid 
        /// data and a subsequent call to the xEof method must return true (non-zero). 
        /// If the cursor is successfully advanced to another row of content, then
        /// subsequent calls to xEof must return false (zero).
        /// </para>
        /// <para>
        /// This method must return SQLITE_OK if successful, or an sqlite 
        /// error code if an error occurs.
        /// </para>
        /// <para>
        /// The xNext method is required for every virtual table implementation.

        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xNext(
            IntPtr pCursor
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xEof)(sqlite3_vtab_cursor*);
        /// </code></para>
        /// <para>
        /// The xEof method must return false (zero) if the specified cursor 
        /// currently points to a valid row of data, or true (non-zero) otherwise. 
        /// This method is called by the SQL engine immediately after each 
        /// xFilter and xNext invocation.
        /// </para>
        /// <para>
        /// The xEof method is required for every virtual table implementation.
        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
................................................................................
        int xEof(
            IntPtr pCursor
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int N);
        /// </code></para>
        /// <para>
        /// The SQLite core invokes this method in order to find the value for 
        /// the N-th column of the current row. N is zero-based so the first column 
        /// is numbered 0. 
        /// The xColumn method may return its result back to SQLite using one of the
        /// following interface:
        /// </para>
        /// <para>
        ///  sqlite3_result_blob()
        ///  sqlite3_result_double()
        ///  sqlite3_result_int()
        ///  sqlite3_result_int64()
        ///  sqlite3_result_null()
        ///  sqlite3_result_text()
        ///  sqlite3_result_text16()
        ///  sqlite3_result_text16le()
        ///  sqlite3_result_text16be()
        ///  sqlite3_result_zeroblob()
        /// </para>
        /// <para>
        /// If the xColumn method implementation calls none of the functions above,
        /// then the value of the column defaults to an SQL NULL.
        /// </para>
        /// <para>
        /// To raise an error, the xColumn method should use one of the result_text() 
        /// methods to set the error message text, then return an appropriate
        /// error code.  The xColumn method must return SQLITE_OK on success.

        /// </para>
        /// <para>
        /// The xColumn method is required for every virtual table implementation.

        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <param name="pContext">
        /// The native pointer to the sqlite3_context structure to be used
................................................................................
            IntPtr pContext,
            int index
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xRowid)(sqlite3_vtab_cursor *pCur, sqlite_int64 *pRowid);
        /// </code></para>
        /// <para>
        /// A successful invocation of this method will cause *pRowid to be
        /// filled with the rowid of row that the
        /// virtual table cursor pCur is currently pointing at.
        /// This method returns SQLITE_OK on success.
        /// It returns an appropriate error code on failure.
        /// </para>
        /// <para>
        /// The xRowid method is required for every virtual table implementation.

        /// </para>
        /// </summary>
        /// <param name="pCursor">
        /// The native pointer to the sqlite3_vtab_cursor derived structure.
        /// </param>
        /// <param name="rowId">
        /// Upon success, this parameter must be modified to contain the unique
................................................................................
            IntPtr pCursor,
            ref long rowId
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xUpdate)(
        ///     sqlite3_vtab *pVTab,
        ///     int argc,
        ///     sqlite3_value **argv,
        ///     sqlite_int64 *pRowid
        ///   );
        /// </code></para>
        /// <para>
        /// All changes to a virtual table are made using the xUpdate method.
        /// This one method can be used to insert, delete, or update.
        /// </para>
        /// <para>
        /// The argc parameter specifies the number of entries in the argv array. 
        /// The value of argc will be 1 for a pure delete operation or N+2 for an insert
        /// or replace or update where N is the number of columns in the table.  
        /// In the previous sentence, N includes any hidden columns.

        /// </para>
        /// <para>
        /// Every argv entry will have a non-NULL value in C but may contain the 
        /// SQL value NULL.  In other words, it is always true that
        /// <tt>argv[i]!=0</tt> for i between 0 and <tt>argc-1</tt>.
        /// However, it might be the case that
        /// <tt>sqlite3_value_type(argv[i])==SQLITE_NULL</tt>.
        /// </para>
        /// <para>
        /// The argv[0] parameter is the rowid of a row in the virtual table 
        /// to be deleted. If argv[0] is an SQL NULL, then no deletion occurs.
        /// </para>
        /// <para>
        /// The argv[1] parameter is the rowid of a new row to be inserted 
        /// into the virtual table. If argv[1] is an SQL NULL, then the implementation 
        /// must choose a rowid for the newly inserted row. Subsequent argv[] 
        /// entries contain values of the columns of the virtual table, in the 
        /// order that the columns were declared. The number of columns will
        /// match the table declaration that the xConnect or xCreate method made 

        /// using the sqlite3_declare_vtab() call.  All hidden columns are included.
        /// </para>
        /// <para>
        /// When doing an insert without a rowid (argc>1, argv[1] is an SQL NULL), the 
        /// implementation must set *pRowid to the rowid of the newly inserted row; 
        /// this will become the value returned by the sqlite3_last_insert_rowid()
        /// function. Setting this value in all the other cases is a harmless no-op;
        /// the SQLite engine ignores the *pRowid return value if argc==1 or 
        /// argv[1] is not an SQL NULL.
        /// </para>
        /// <para>
        /// Each call to xUpdate will fall into one of cases shown below.
        /// Not that references to argv[i] mean the SQL value
        /// held within the argv[i] object, not the argv[i]
        /// object itself.
        /// </para>
        /// <para><code>
        /// argc = 1


        /// The single row with rowid equal to argv[0] is deleted. No insert occurs.



        /// argc &gt; 1 
        ///  argv[0] = NULL


        /// A new row is inserted with a rowid argv[1] and column values in
        ///        argv[2] and following.  If argv[1] is an SQL NULL,
        ///        the a new unique rowid is generated automatically.


        /// argc &gt; 1 
        ///  argv[0] &#8800; NULL 
        ///  argv[0] = argv[1]


        /// The row with rowid argv[0] is updated with new values 
        ///        in argv[2] and following parameters.


        /// argc &gt; 1 
        ///  argv[0] &#8800; NULL 
        ///  argv[0] &#8800; argv[1]


        ///  The row with rowid argv[0] is updated with rowid argv[1] 
        /// and new values in argv[2] and following parameters. This will occur 
        /// when an SQL statement updates a rowid, as in the statement:

        /// <para><code>

        ///    UPDATE table SET rowid=rowid+1 WHERE ...; 
        /// </code></para>
        /// </code></para>
        /// <para>
        /// The xUpdate method must return SQLITE_OK if and only if it is
        /// successful.  If a failure occurs, the xUpdate must return an appropriate
        /// error code.  On a failure, the pVTab->zErrMsg element may optionally
        /// be replaced with error message text stored in memory allocated from SQLite 
        /// using functions such as sqlite3_mprintf() or sqlite3_malloc().

        /// </para>
        /// <para>
        /// If the xUpdate method violates some constraint of the virtual table
        /// (including, but not limited to, attempting to store a value of the wrong 
        /// datatype, attempting to store a value that is too
        /// large or too small, or attempting to change a read-only value) then the
        /// xUpdate must fail with an appropriate error code.
        /// </para>
        /// <para>
        /// There might be one or more sqlite3_vtab_cursor objects open and in use 
        /// on the virtual table instance and perhaps even on the row of the virtual
        /// table when the xUpdate method is invoked.  The implementation of
        /// xUpdate must be prepared for attempts to delete or modify rows of the table
        /// out from other existing cursors.  If the virtual table cannot accommodate
        /// such changes, the xUpdate method must return an error code.

        /// </para>
        /// <para>
        /// The xUpdate method is optional.
        /// If the xUpdate pointer in the sqlite3_module for a virtual table
        /// is a NULL pointer, then the virtual table is read-only.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="argc">
        /// The number of new or modified column values contained in
................................................................................
            IntPtr argv,
            ref long rowId
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xBegin)(sqlite3_vtab *pVTab);
        /// </code></para>
        /// <para>
        /// This method begins a transaction on a virtual table.
        /// This is method is optional.  The xBegin pointer of sqlite3_module
        /// may be NULL.
        /// </para>
        /// <para>
        /// This method is always followed by one call to either the
        /// xCommit or xRollback method.  Virtual table transactions do
        /// not nest, so the xBegin method will not be invoked more than once
        /// on a single virtual table
        /// without an intervening call to either xCommit or xRollback.
        /// Multiple calls to other methods can and likely will occur in between
        /// the xBegin and the corresponding xCommit or xRollback.

        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <returns>
        /// A standard SQLite return code.
................................................................................
        SQLiteErrorCode xBegin(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xSync)(sqlite3_vtab *pVTab);
        /// </code></para>
        /// <para>
        /// This method signals the start of a two-phase commit on a virtual
        /// table.
        /// This is method is optional.  The xSync pointer of sqlite3_module
        /// may be NULL.
        /// </para>
        /// <para>
        /// This method is only invoked after call to the xBegin method and
        /// prior to an xCommit or xRollback.  In order to implement two-phase
        /// commit, the xSync method on all virtual tables is invoked prior to
        /// invoking the xCommit method on any virtual table.  If any of the 
        /// xSync methods fail, the entire transaction is rolled back.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <returns>
................................................................................
        SQLiteErrorCode xSync(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xCommit)(sqlite3_vtab *pVTab);
        /// </code></para>
        /// <para>
        /// This method causes a virtual table transaction to commit.
        /// This is method is optional.  The xCommit pointer of sqlite3_module

        /// may be NULL.
        /// </para>
        /// <para>
        /// A call to this method always follows a prior call to xBegin and
        /// xSync.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
................................................................................
        SQLiteErrorCode xCommit(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xRollback)(sqlite3_vtab *pVTab);
        /// </code></para>
        /// <para>
        /// This method causes a virtual table transaction to rollback.
        /// This is method is optional.  The xRollback pointer of sqlite3_module

        /// may be NULL.
        /// </para>
        /// <para>
        /// A call to this method always follows a prior call to xBegin.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
................................................................................
        SQLiteErrorCode xRollback(
            IntPtr pVtab
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xFindFunction)(
        ///     sqlite3_vtab *pVtab,
        ///     int nArg,
        ///     const char *zName,
        ///     void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
        ///     void **ppArg
        ///   );
        /// </code></para>
        /// <para>
        /// This method is called during sqlite3_prepare() to give the virtual
        /// table implementation an opportunity to overload functions. 
        /// This method may be set to NULL in which case no overloading occurs.
        /// </para>
        /// <para>


        /// When a function uses a column from a virtual table as its first 
        /// argument, this method is called to see if the virtual table would 
        /// like to overload the function. The first three parameters are inputs: 
        /// the virtual table, the number of arguments to the function, and the 
        /// name of the function. If no overloading is desired, this method
        /// returns 0. To overload the function, this method writes the new 
        /// function implementation into *pxFunc and writes user data into *ppArg 
        /// and returns 1.
        /// </para>
        /// <para>
        /// Note that infix functions (LIKE, GLOB, REGEXP, and MATCH) reverse 
        /// the order of their arguments. So "like(A,B)" is equivalent to "B like A". 
        /// For the form "B like A" the B term is considered the first argument 
        /// to the function. But for "like(A,B)" the A term is considered the 
        /// first argument.
        /// </para>
        /// <para>
        /// The function pointer returned by this routine must be valid for
        /// the lifetime of the sqlite3_vtab object given in the first parameter.
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="nArg">
        /// The number of arguments to the function being sought.
................................................................................
            ref SQLiteCallback callback,
            ref IntPtr pClientData
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
        /// </code></para>
        /// <para>
        /// This method provides notification that the virtual table implementation
        /// that the virtual table will be given a new name. 
        /// If this method returns SQLITE_OK then SQLite renames the table.
        /// If this method returns an error code then the renaming is prevented.
        /// </para>
        /// <para>
        /// The xRename method is required for every virtual table implementation.

        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="zNew">
        /// The native pointer to the UTF-8 encoded string containing the new
................................................................................
            IntPtr pVtab,
            IntPtr zNew
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xSavepoint)(sqlite3_vtab *pVtab, int);
        ///   int (*xRelease)(sqlite3_vtab *pVtab, int);
        ///   int (*xRollbackTo)(sqlite3_vtab *pVtab, int);
        /// </code></para>
        /// <para>
        /// These methods provide the virtual table implementation an opportunity to
        /// implement nested transactions.  They are always optional and will only be
        /// called in SQLite version 3.7.7 and later.
        /// </para>
        /// <para>
        /// When xSavepoint(X,N) is invoked, that is a signal to the virtual table X
        /// that it should save its current state as savepoint N.  
        /// A subsequent call
        /// to xRollbackTo(X,R) means that the state of the virtual table should return
        /// to what it was when xSavepoint(X,R) was last called.  
        /// The call
        /// to xRollbackTo(X,R) will invalidate all savepoints with N>R; none of the
        /// invalided savepoints will be rolled back or released without first
        /// being reinitialized by a call to xSavepoint().  
        /// A call to xRelease(X,M) invalidates all savepoints where N>=M.

        /// </para>
        /// <para>
        /// None of the xSavepoint(), xRelease(), or xRollbackTo() methods will ever
        /// be called except in between calls to xBegin() and 
        /// either xCommit() or xRollback().
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="iSavepoint">
        /// This is an integer identifier under which the the current state of
................................................................................
            IntPtr pVtab,
            int iSavepoint
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xSavepoint)(sqlite3_vtab *pVtab, int);
        ///   int (*xRelease)(sqlite3_vtab *pVtab, int);
        ///   int (*xRollbackTo)(sqlite3_vtab *pVtab, int);
        /// </code></para>
        /// <para>
        /// These methods provide the virtual table implementation an opportunity to
        /// implement nested transactions.  They are always optional and will only be
        /// called in SQLite version 3.7.7 and later.
        /// </para>
        /// <para>
        /// When xSavepoint(X,N) is invoked, that is a signal to the virtual table X
        /// that it should save its current state as savepoint N.  
        /// A subsequent call
        /// to xRollbackTo(X,R) means that the state of the virtual table should return
        /// to what it was when xSavepoint(X,R) was last called.  
        /// The call
        /// to xRollbackTo(X,R) will invalidate all savepoints with N>R; none of the
        /// invalided savepoints will be rolled back or released without first
        /// being reinitialized by a call to xSavepoint().  
        /// A call to xRelease(X,M) invalidates all savepoints where N>=M.

        /// </para>
        /// <para>
        /// None of the xSavepoint(), xRelease(), or xRollbackTo() methods will ever
        /// be called except in between calls to xBegin() and 
        /// either xCommit() or xRollback().
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="iSavepoint">
        /// This is an integer used to indicate that any saved states with an
................................................................................
            IntPtr pVtab,
            int iSavepoint
            );

        ///////////////////////////////////////////////////////////////////////

        /// <summary>
        /// <para><code>
        ///   int (*xSavepoint)(sqlite3_vtab *pVtab, int);
        ///   int (*xRelease)(sqlite3_vtab *pVtab, int);
        ///   int (*xRollbackTo)(sqlite3_vtab *pVtab, int);
        /// </code></para>
        /// <para>
        /// These methods provide the virtual table implementation an opportunity to
        /// implement nested transactions.  They are always optional and will only be
        /// called in SQLite version 3.7.7 and later.
        /// </para>
        /// <para>
        /// When xSavepoint(X,N) is invoked, that is a signal to the virtual table X
        /// that it should save its current state as savepoint N.  
        /// A subsequent call
        /// to xRollbackTo(X,R) means that the state of the virtual table should return
        /// to what it was when xSavepoint(X,R) was last called.  
        /// The call
        /// to xRollbackTo(X,R) will invalidate all savepoints with N>R; none of the
        /// invalided savepoints will be rolled back or released without first
        /// being reinitialized by a call to xSavepoint().  
        /// A call to xRelease(X,M) invalidates all savepoints where N>=M.

        /// </para>
        /// <para>
        /// None of the xSavepoint(), xRelease(), or xRollbackTo() methods will ever
        /// be called except in between calls to xBegin() and 
        /// either xCommit() or xRollback().
        /// </para>
        /// </summary>
        /// <param name="pVtab">
        /// The native pointer to the sqlite3_vtab derived structure.
        /// </param>
        /// <param name="iSavepoint">
        /// This is an integer identifier used to specify a specific saved
        /// state for the virtual table for it to restore itself back to, which
        /// should also have the effect of deleting all saved states with an
        /// integer identifier greater than this one.

        /// </param>
        /// <returns>
        /// A standard SQLite return code.
        /// </returns>
        SQLiteErrorCode xRollbackTo(
            IntPtr pVtab,
            int iSavepoint
            );
    }
    #endregion
}