SQLite

** Existing configuration options might be discontinued.  Applications
** should check the return code from [sqlite3_db_config()] to make sure that
** the call worked.  ^The [sqlite3_db_config()] interface will return a
** non-zero [error code] if a discontinued or unsupported configuration option
** is invoked.
**
** <dl>
** [[SQLITE_DBCONFIG_LOOKASIDE]]
** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
** <dd> ^This option takes three additional arguments that determine the 
** [lookaside memory allocator] configuration for the [database connection].
** ^The first argument (the third parameter to [sqlite3_db_config()] is a
** pointer to a memory buffer to use for lookaside memory.
** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
** may be NULL in which case SQLite will allocate the

** connection is not currently using lookaside memory, or in other words
** when the "current value" returned by
** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
** Any attempt to change the lookaside memory configuration when lookaside
** memory is in use leaves the configuration unchanged and returns 
** [SQLITE_BUSY].)^</dd>
**
** [[SQLITE_DBCONFIG_ENABLE_FKEY]]
** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
** <dd> ^This option is used to enable or disable the enforcement of
** [foreign key constraints].  There should be two additional arguments.
** The first argument is an integer which is 0 to disable FK enforcement,
** positive to enable FK enforcement or negative to leave FK enforcement
** unchanged.  The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether FK enforcement is off or on
** following this call.  The second parameter may be a NULL pointer, in
** which case the FK enforcement setting is not reported back. </dd>
**
** [[SQLITE_DBCONFIG_ENABLE_TRIGGER]]
** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
** There should be two additional arguments.
** The first argument is an integer which is 0 to disable triggers,
** positive to enable triggers or negative to leave the setting unchanged.
** The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether triggers are disabled or enabled
** following this call.  The second parameter may be a NULL pointer, in
** which case the trigger setting is not reported back. </dd>
**
** [[SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER]]
** <dt>SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER</dt>
** <dd> ^This option is used to enable or disable the two-argument
** version of the [fts3_tokenizer()] function which is part of the
** [FTS3] full-text search engine extension.
** There should be two additional arguments.
** The first argument is an integer which is 0 to disable fts3_tokenizer() or
** positive to enable fts3_tokenizer() or negative to leave the setting
** unchanged.
** The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether fts3_tokenizer is disabled or enabled
** following this call.  The second parameter may be a NULL pointer, in
** which case the new setting is not reported back. </dd>
**
** [[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION]]
** <dt>SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION</dt>
** <dd> ^This option is used to enable or disable the [sqlite3_load_extension()]
** interface independently of the [load_extension()] SQL function.
** The [sqlite3_enable_load_extension()] API enables or disables both the
** C-API [sqlite3_load_extension()] and the SQL function [load_extension()].
** There should be two additional arguments.
** When the first argument to this interface is 1, then only the C-API is
** enabled and the SQL function remains disabled.  If the first argument to
** this interface is 0, then both the C-API and the SQL function are disabled.
** If the first argument is -1, then no changes are made to state of either the
** C-API or the SQL function.
** The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether [sqlite3_load_extension()] interface
** is disabled or enabled following this call.  The second parameter may
** be a NULL pointer, in which case the new setting is not reported back.
** </dd>
**
** [[SQLITE_DBCONFIG_MAINDBNAME]] <dt>SQLITE_DBCONFIG_MAINDBNAME</dt>
** <dd> ^This option is used to change the name of the "main" database
** schema.  ^The sole argument is a pointer to a constant UTF8 string
** which will become the new schema name in place of "main".  ^SQLite
** does not make a copy of the new main schema name string, so the application
** must ensure that the argument passed into this DBCONFIG option is unchanged
** until after the database connection closes.
** </dd>
**
** [[SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE]] 
** <dt>SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE</dt>
** <dd> Usually, when a database in wal mode is closed or detached from a 
** database handle, SQLite checks if this will mean that there are now no 
** connections at all to the database. If so, it performs a checkpoint 
** operation before closing the connection. This option may be used to
** override this behaviour. The first parameter passed to this operation
** is an integer - positive to disable checkpoints-on-close, or zero (the
** default) to enable them, and negative to leave the setting unchanged.
** The second parameter is a pointer to an integer
** into which is written 0 or 1 to indicate whether checkpoints-on-close
** have been disabled - 0 if they are not disabled, 1 if they are.
** </dd>
**
** [[SQLITE_DBCONFIG_ENABLE_QPSG]] <dt>SQLITE_DBCONFIG_ENABLE_QPSG</dt>
** <dd>^(The SQLITE_DBCONFIG_ENABLE_QPSG option activates or deactivates
** the [query planner stability guarantee] (QPSG).  When the QPSG is active,
** a single SQL query statement will always use the same algorithm regardless
** of values of [bound parameters].)^ The QPSG disables some query optimizations
** that look at the values of bound parameters, which can make some queries
** slower.  But the QPSG has the advantage of more predictable behavior.  With
** the QPSG active, SQLite will always use the same query plan in the field as
** was used during testing in the lab.
** The first argument to this setting is an integer which is 0 to disable 
** the QPSG, positive to enable QPSG, or negative to leave the setting
** unchanged. The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether the QPSG is disabled or enabled
** following this call.
** </dd>
**
** [[SQLITE_DBCONFIG_TRIGGER_EQP]] <dt>SQLITE_DBCONFIG_TRIGGER_EQP</dt>
** <dd> By default, the output of EXPLAIN QUERY PLAN commands does not 
** include output for any operations performed by trigger programs. This
** option is used to set or clear (the default) a flag that governs this
** behavior. The first parameter passed to this operation is an integer -
** positive to enable output for trigger programs, or zero to disable it,
** or negative to leave the setting unchanged.
** The second parameter is a pointer to an integer into which is written 
** 0 or 1 to indicate whether output-for-triggers has been disabled - 0 if 
** it is not disabled, 1 if it is.  
** </dd>
**
** [[SQLITE_DBCONFIG_RESET_DATABASE]] <dt>SQLITE_DBCONFIG_RESET_DATABASE</dt>
** <dd> Set the SQLITE_DBCONFIG_RESET_DATABASE flag and then run
** [VACUUM] in order to reset a database back to an empty database
** with no schema and no content. The following process works even for
** a badly corrupted database file:
** <ol>
** <li> If the database connection is newly opened, make sure it has read the
**      database schema by preparing then discarding some query against the
**      database, or calling sqlite3_table_column_metadata(), ignoring any
**      errors.  This step is only necessary if the application desires to keep
**      the database in WAL mode after the reset if it was in WAL mode before
**      the reset.  
** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 1, 0);
** <li> [sqlite3_exec](db, "[VACUUM]", 0, 0, 0);
** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 0, 0);
** </ol>
** Because resetting a database is destructive and irreversible, the
** process requires the use of this obscure API and multiple steps to help
** ensure that it does not happen by accident.
**
** [[SQLITE_DBCONFIG_DEFENSIVE]] <dt>SQLITE_DBCONFIG_DEFENSIVE</dt>
** <dd>The SQLITE_DBCONFIG_DEFENSIVE option activates or deactivates the
** "defensive" flag for a database connection.  When the defensive
** flag is enabled, language features that allow ordinary SQL to 
** deliberately corrupt the database file are disabled.  The disabled
** features include but are not limited to the following:
** <ul>
** <li> The [PRAGMA writable_schema=ON] statement.
** <li> Writes to the [sqlite_dbpage] virtual table.
** <li> Direct writes to [shadow tables].
** </ul>
** </dd>
** </dl>
*/
#define SQLITE_DBCONFIG_MAINDBNAME            1000 /* const char* */
#define SQLITE_DBCONFIG_LOOKASIDE             1001 /* void* int int */
#define SQLITE_DBCONFIG_ENABLE_FKEY           1002 /* int int* */

** CAPI3REF: Virtual Table Configuration Options
**
** These macros define the various options to the
** [sqlite3_vtab_config()] interface that [virtual table] implementations
** can use to customize and optimize their behavior.
**
** <dl>
** [[SQLITE_VTAB_CONSTRAINT_SUPPORT]]
** <dt>SQLITE_VTAB_CONSTRAINT_SUPPORT
** <dd>Calls of the form
** [sqlite3_vtab_config](db,SQLITE_VTAB_CONSTRAINT_SUPPORT,X) are supported,
** where X is an integer.  If X is zero, then the [virtual table] whose
** [xCreate] or [xConnect] method invoked [sqlite3_vtab_config()] does not
** support constraints.  In this configuration (which is the default) if
** a call to the [xUpdate] method returns [SQLITE_CONSTRAINT], then the entire