The following special replacement tokens may be recognized and replaced with their associated runtime value, depending on context, when setting values are being read by the native library pre-loading subsystem. Unless otherwise stated explicitly, all of these tokens are case-sensitive and the percent characters must be included in order for them to be recognized.
All references to special replacement tokens will be expanded to their corresponding values within the returned settings values unless either the "No_Tokens" or "No_Tokens_<name>" environment variable is set [to anything].
| Name | Description |
|---|---|
| %PreLoadSQLite_AssemblyDirectory% | If this token (which is case-sensitive and must include the percent characters) is present within a setting value being returned, it will be replaced with the qualified name of the directory containing the System.Data.SQLite assembly. If the name of the directory is not available, the token will not be replaced. |
| %PreLoadSQLite_TargetFramework% | If this token (which is case-sensitive and must include the percent characters) is present within a setting value being returned, it will be replaced with an abbreviation of the target framework attribute value for the System.Data.SQLite assembly. If the target framework attribute value is not available, the token will not be replaced. |
| %PreLoadSQLite_XmlConfigDirectory% | If this token (which is case-sensitive and must include the percent characters) is present within a setting value being returned, it will be replaced with the qualified name of the directory containing the XML configuration file. If the name of the directory is not available, the token will not be replaced. Generally, this token may only be used within the XML configuration file itself. |
These environment variables are used to control several features of the System.Data.SQLite library. All of these environment variables are optional. If a particular environment variable is not present, the XML configuration file "System.Data.SQLite.dll.config" in the directory containing the currently executing assembly (i.e. the one containing all the managed components for System.Data.SQLite) will also be consulted. If present, the XML configuration file should be structured as follows:
<?xml version="1.0"?>
<configuration>
<appSettings>
<add key="A_Setting" value="String Value" />
<add key="Another_Setting" value="%ENV_VALUE%" />
</appSettings>
</configuration>
All references to existing environment variables will be expanded to their corresponding values within the returned settings values unless either the "No_Expand" or "No_Expand_<name>" environment variable is set [to anything].
None of these environment variables are supported by the Compact Framework builds of System.Data.SQLite, due to limitations imposed by the platform itself; however, the XML configuration file mentioned above may be used instead.
| Name | Description |
|---|---|
| AppendManifestToken_SQLiteProviderManifest | If this environment variable is set [to anything], it will be used by the System.Data.SQLite.Linq.SQLiteProviderManifest class (and the System.Data.SQLite.EF6.SQLiteProviderManifest class) to modify future provider manifest tokens by appending the value of the environment variable to the existing provider manifest token, if any. Typically, in order for the constructed provider manifest token to be syntactically correct, the environment variable value [to be appended] must begin with a semicolon. |
| DefaultFlags_SQLiteConnection | If this environment variable is set [to anything], it will be used by the System.Data.SQLite.SQLiteConnection class as the default flags for all opened connections (i.e. when they are not present in the connection string). |
| Disable_SQLiteLog | If this configuration variable is set [to anything], the SQLite logging subsystem will be initially disabled when initialized. |
| Force_SQLiteLog | If this environment variable is set [to anything], the SQLite logging subsystem may be initialized in a non-default application domain. By default, this is not allowed due to the potential for application domain unloading issues. |
| Initialize_SQLiteLog | If this environment variable is set [to anything], the SQLite logging subsystem will attempt to perform initialization even when an attempt was previously made. |
| No_PreLoadSQLite | If this environment variable is set [to anything], the native library pre-loading code will be disabled. By default, the native library pre-loading code will attempt to load the native SQLite library from architecture-specific (e.g. "x86", "amd64", "x64") or platform-specific (e.g. "Win32") directories that reside underneath the application base directory. |
| No_SQLiteConnectionNewParser | If this environment variable is set [to anything], the new connection string parsing algorithm will not be used. This environment variable is intended for use with legacy code only. |
| No_SQLiteFunctions | If this environment variable is set [to anything], the initial search for types in all loaded assemblies that are tagged with the SQLiteFunction attribute will be skipped. Normally, this search is conducted only once per application domain by the static constructor of the SQLiteFunction class; however, these implementation details are subject to change. |
| No_SQLiteGetSettingValue | If this environment variable is set [to anything], all calls to the GetSettingValue method will return the default value. This will effectively prevent all other setting values from having any effect, including those specified via other supported environment variables or in the associated XML configuration file. |
| No_SQLiteLog | If this environment variable is set [to anything], the SQLite logging subsystem will not be initialized by the SQLiteLog class; however, it may still be initialized by external components (i.e. something other than System.Data.SQLite). |
| No_SQLiteXmlConfigFile | If this environment variable is set [to anything], calls to the GetSettingValue method will never result in the XML configuration file being read; instead, the default value will be returned. This will effectively prevent any setting values specified via the XML configuration file from having any effect. |
| PreLoadSQLite_AllowBaseDirectoryOnly | If this environment variable is set [to anything], the base directory itself is considered valid for pre-loading the native SQLite library. |
| PreLoadSQLite_BaseDirectory | If this environment variable is set [to anything], it will be used instead of the application base directory by the native library pre-loader. This environment variable can be especially useful in ASP.NET and other hosted environments where direct control of the location of the managed assemblies is not under the control of the application. |
| PreLoadSQLite_BreakIntoDebugger | If this environment variable is set [to anything], the native library pre-loader subsystem will attempt to give the interactive user an opportunity to attach a debugger to the current process. |
| PreLoadSQLite_LibraryFileNameOnly | If this environment variable is set [to anything], it will be used as the base file name (without directory information) for the native SQLite library to be pre-loaded (e.g. "sqlite3.dll" or "libsqlite3.so.0"). |
| PreLoadSQLite_NoSearchForDirectory | If this environment variable is set [to anything], the native library pre-loading code will skip conducting a search for the native library to pre-load. By default, the search starts in the location of the currently executing assembly (i.e. the assembly containing all the managed components for System.Data.SQLite) and then falls back to the application domain base directory. |
| PreLoadSQLite_ProcessorArchitecture | If this environment variable is set [to anything], it will be used instead of the processor architecture value contained in the PROCESSOR_ARCHITECTURE environment variable to help build the path of the native library to pre-load. |
| PreLoadSQLite_UseAssemblyDirectory | If this environment variable is set [to anything], the location of the currently executing assembly (i.e. the one containing all the managed components for System.Data.SQLite) will be used as the basis for locating the the native library to pre-load (i.e. instead of using the application domain base directory). |
| PROCESSOR_ARCHITECTURE | This environment variable is normally set by the operating system itself and should reflect the native processor architecture of the current process (e.g. a 32-bit x86 application running on a 64-bit x64 operating system should have the value "x86"). |
| SQLite_ForceLogLifecycle | If this environment variable is set [to anything], calls into key members pertaining to the lifecycle of connections and their associated classes (e.g. LINQ, EF6, etc) will be logged. |
| SQLite_ForceLogPrepare | If this environment variable is set [to anything], all calls to prepare a SQL query will be logged, regardless of the flags for the associated connection. |
| SQLite_ForceLogRetry | If this environment variable is set [to anything], all internal retries during statment preparation and stepping will be logged, regardless of the flags for the associated connection. |
| SQLite_GlobalCommandBehaviors | If this environment variable is set [to anything], it will be processed as a list of CommandBehavior flags, if possible. It will be ignored if it cannot be processed correctly. For more details please refer to the CombineBehaviors method. |
| SQLite_LegacyEncryptPage1 | If this environment variable is set [to anything], page #1 of database files encrypted using the (unsupported) legacy CryptoAPI-based (RC4) codec will be encrypted. This was the default behavior prior to release 1.0.112.3; however, it is now disabled (by default) as it can cause corruption and/or other malfunctions in some circumstances. Please do not use this environment variable unless it is absolutely necessary for your specific use case. |
| SQLite_StrongConnectionPool | If this environment variable is set [to anything], the default connection pool will use normal objects instead of weak references. This should prevent any pooled connection objects from ever being automatically cleaned up by the garbage collector. |
| SQLite_TraceCategories | If this environment variable is set [to anything], it will be processed as a list of trace categories to enable, if possible. It will be ignored if it cannot be processed correctly. For more details, please refer to the ParseTraceCategories method. |
| TypeName_SQLiteProviderServices | If this environment variable is set [to anything], it will be used by the System.Data.SQLite.SQLiteFactory class as the type name containing the System.Data.Common.DbProviderServices implementation that should be used. |
| Use_SQLiteConvert_DefaultDbType | If this environment variable is set [to anything], it will be used by the System.Data.SQLite.SQLiteConvert class as the default DbType value that should be used when a per-connection value is not available. |
| Use_SQLiteConvert_DefaultTypeName | If this environment variable is set [to anything], it will be used by the System.Data.SQLite.SQLiteConvert class as the default type name that should be used when a per-connection value is not available. |