Updated: 2021/Apr/14


SQLITE_DBCONFIG_MAINDBNAME(3)                         Library Functions Manual

NAME
     SQLITE_DBCONFIG_MAINDBNAME, SQLITE_DBCONFIG_LOOKASIDE,
     SQLITE_DBCONFIG_ENABLE_FKEY, SQLITE_DBCONFIG_ENABLE_TRIGGER,
     SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER,
     SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE,
     SQLITE_DBCONFIG_ENABLE_QPSG, SQLITE_DBCONFIG_TRIGGER_EQP,
     SQLITE_DBCONFIG_RESET_DATABASE, SQLITE_DBCONFIG_DEFENSIVE,
     SQLITE_DBCONFIG_MAX - Database Connection Configuration Options

SYNOPSIS
     #define SQLITE_DBCONFIG_MAINDBNAME
     #define SQLITE_DBCONFIG_LOOKASIDE
     #define SQLITE_DBCONFIG_ENABLE_FKEY
     #define SQLITE_DBCONFIG_ENABLE_TRIGGER
     #define SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER
     #define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION
     #define SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE
     #define SQLITE_DBCONFIG_ENABLE_QPSG
     #define SQLITE_DBCONFIG_TRIGGER_EQP
     #define SQLITE_DBCONFIG_RESET_DATABASE
     #define SQLITE_DBCONFIG_DEFENSIVE
     #define SQLITE_DBCONFIG_MAX

DESCRIPTION
     These constants are the available integer configuration options that can
     be passed as the second argument to the sqlite3_db_config() interface.

     New configuration options may be added in future releases of 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.

     SQLITE_DBCONFIG_LOOKASIDE
             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 lookaside buffer itself using sqlite3_malloc().
             The second argument is the size of each lookaside buffer slot.
             The third argument is the number of slots.  The size of the
             buffer in the first argument must be greater than or equal to the
             product of the second and third arguments.  The buffer must be
             aligned to an 8-byte boundary.  If the second argument to
             SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is
             internally rounded down to the next smaller multiple of 8.  The
             lookaside memory configuration for a database connection can only
             be changed when that 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.

     SQLITE_DBCONFIG_ENABLE_FKEY
             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.

     SQLITE_DBCONFIG_ENABLE_TRIGGER
             This option is used to enable or disable  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.

     SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER
             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.

     SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION
             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.

     SQLITE_DBCONFIG_MAINDBNAME
             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.

     SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE
             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.

     SQLITE_DBCONFIG_ENABLE_QPSG
             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.

     SQLITE_DBCONFIG_TRIGGER_EQP
             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.

     SQLITE_DBCONFIG_RESET_DATABASE
             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:

             1.   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.

             2.   sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 1, 0);

             3.   sqlite3_exec(db, "VACUUM", 0, 0, 0);

             4.   sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 0, 0);

             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
             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:

                The PRAGMA writable_schema=ON statement.

                Writes to the sqlite_dbpage virtual table.

                Direct writes to shadow tables.

SEE ALSO
     sqlite3(3), sqlite3_db_config(3), sqlite3_db_status(3),
     sqlite3_enable_load_extension(3), sqlite3_exec(3),
     sqlite3_load_extension(3), sqlite3_malloc(3), SQLITE_OK(3),
     SQLITE_CONFIG_SINGLETHREAD(3)

NetBSD 9.99                    December 19, 2018                   NetBSD 9.99