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<!-- keywords: SQLITE_DBCONFIG_DEFENSIVE SQLITE_DBCONFIG_DQS_DDL SQLITE_DBCONFIG_DQS_DML SQLITE_DBCONFIG_ENABLE_FKEY SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION SQLITE_DBCONFIG_ENABLE_QPSG SQLITE_DBCONFIG_ENABLE_TRIGGER SQLITE_DBCONFIG_ENABLE_VIEW SQLITE_DBCONFIG_LEGACY_ALTER_TABLE SQLITE_DBCONFIG_LEGACY_FILE_FORMAT SQLITE_DBCONFIG_LOOKASIDE SQLITE_DBCONFIG_MAINDBNAME SQLITE_DBCONFIG_MAX SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE SQLITE_DBCONFIG_RESET_DATABASE SQLITE_DBCONFIG_REVERSE_SCANORDER SQLITE_DBCONFIG_STMT_SCANSTATUS SQLITE_DBCONFIG_TRIGGER_EQP SQLITE_DBCONFIG_TRUSTED_SCHEMA SQLITE_DBCONFIG_WRITABLE_SCHEMA -->
<div class=nosearch>
<a href="../c3ref/intro.html"><h2>SQLite C Interface</h2></a>
<h2>Database Connection Configuration Options</h2>
</div>
<blockquote><pre>
#define SQLITE_DBCONFIG_MAINDBNAME 1000 /* const char* */
#define SQLITE_DBCONFIG_LOOKASIDE 1001 /* void* int int */
#define SQLITE_DBCONFIG_ENABLE_FKEY 1002 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_TRIGGER 1003 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER 1004 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1005 /* int int* */
#define SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE 1006 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_QPSG 1007 /* int int* */
#define SQLITE_DBCONFIG_TRIGGER_EQP 1008 /* int int* */
#define SQLITE_DBCONFIG_RESET_DATABASE 1009 /* int int* */
#define SQLITE_DBCONFIG_DEFENSIVE 1010 /* int int* */
#define SQLITE_DBCONFIG_WRITABLE_SCHEMA 1011 /* int int* */
#define SQLITE_DBCONFIG_LEGACY_ALTER_TABLE 1012 /* int int* */
#define SQLITE_DBCONFIG_DQS_DML 1013 /* int int* */
#define SQLITE_DBCONFIG_DQS_DDL 1014 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_VIEW 1015 /* int int* */
#define SQLITE_DBCONFIG_LEGACY_FILE_FORMAT 1016 /* int int* */
#define SQLITE_DBCONFIG_TRUSTED_SCHEMA 1017 /* int int* */
#define SQLITE_DBCONFIG_STMT_SCANSTATUS 1018 /* int int* */
#define SQLITE_DBCONFIG_REVERSE_SCANORDER 1019 /* int int* */
#define SQLITE_DBCONFIG_MAX 1019 /* Largest DBCONFIG */
</pre></blockquote>
<p>
These constants are the available integer configuration options that
can be passed as the second argument to the <a href="../c3ref/db_config.html">sqlite3_db_config()</a> interface.</p>
<p>New configuration options may be added in future releases of SQLite.
Existing configuration options might be discontinued. Applications
should check the return code from <a href="../c3ref/db_config.html">sqlite3_db_config()</a> to make sure that
the call worked. The <a href="../c3ref/db_config.html">sqlite3_db_config()</a> interface will return a
non-zero <a href="../rescode.html">error code</a> if a discontinued or unsupported configuration option
is invoked.</p>
<p><dl>
<a name="sqlitedbconfiglookaside"></a>
<dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
<dd> This option takes three additional arguments that determine the
<a href="../malloc.html#lookaside">lookaside memory allocator</a> configuration for the <a href="../c3ref/sqlite3.html">database connection</a>.
The first argument (the third parameter to <a href="../c3ref/db_config.html">sqlite3_db_config()</a> 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 <a href="../c3ref/free.html">sqlite3_malloc()</a>. 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
<a href="../c3ref/db_status.html">sqlite3_db_status</a>(D,<a href="../c3ref/c_dbstatus_options.html#sqlitedbstatuslookasideused">SQLITE_DBSTATUS_LOOKASIDE_USED</a>,...) is zero.
Any attempt to change the lookaside memory configuration when lookaside
memory is in use leaves the configuration unchanged and returns
<a href="../rescode.html#busy">SQLITE_BUSY</a>.</dd></p>
<p><a name="sqlitedbconfigenablefkey"></a>
<dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
<dd> This option is used to enable or disable the enforcement of
<a href="../foreignkeys.html">foreign key constraints</a>. 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></p>
<p><a name="sqlitedbconfigenabletrigger"></a>
<dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
<dd> This option is used to enable or disable <a href="../lang_createtrigger.html">triggers</a>.
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.</p>
<p><p>Originally this option disabled all triggers. However, since
SQLite version 3.35.0, TEMP triggers are still allowed even if
this option is off. So, in other words, this option now only disables
triggers in the main database schema or in the schemas of ATTACH-ed
databases. </dd></p>
<p><a name="sqlitedbconfigenableview"></a>
<dt>SQLITE_DBCONFIG_ENABLE_VIEW</dt>
<dd> This option is used to enable or disable <a href="../lang_createview.html">views</a>.
There should be two additional arguments.
The first argument is an integer which is 0 to disable views,
positive to enable views 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 views are disabled or enabled
following this call. The second parameter may be a NULL pointer, in
which case the view setting is not reported back.</p>
<p><p>Originally this option disabled all views. However, since
SQLite version 3.35.0, TEMP views are still allowed even if
this option is off. So, in other words, this option now only disables
views in the main database schema or in the schemas of ATTACH-ed
databases. </dd></p>
<p><a name="sqlitedbconfigenablefts3tokenizer"></a>
<dt>SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER</dt>
<dd> This option is used to enable or disable the
<a href="../fts3.html#f3tknzr">fts3_tokenizer()</a> function which is part of the
<a href="../fts3.html">FTS3</a> 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></p>
<p><a name="sqlitedbconfigenableloadextension"></a>
<dt>SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION</dt>
<dd> This option is used to enable or disable the <a href="../c3ref/load_extension.html">sqlite3_load_extension()</a>
interface independently of the <a href="../lang_corefunc.html#load_extension">load_extension()</a> SQL function.
The <a href="../c3ref/enable_load_extension.html">sqlite3_enable_load_extension()</a> API enables or disables both the
C-API <a href="../c3ref/load_extension.html">sqlite3_load_extension()</a> and the SQL function <a href="../lang_corefunc.html#load_extension">load_extension()</a>.
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 <a href="../c3ref/load_extension.html">sqlite3_load_extension()</a> 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></p>
<p><a name="sqlitedbconfigmaindbname"></a>
<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></p>
<p><a name="sqlitedbconfignockptonclose"></a>
<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 behavior. 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></p>
<p><a name="sqlitedbconfigenableqpsg"></a>
<dt>SQLITE_DBCONFIG_ENABLE_QPSG</dt>
<dd>The SQLITE_DBCONFIG_ENABLE_QPSG option activates or deactivates
the <a href="../queryplanner-ng.html#qpstab">query planner stability guarantee</a> (QPSG). When the QPSG is active,
a single SQL query statement will always use the same algorithm regardless
of values of <a href="../lang_expr.html#varparam">bound parameters</a>. 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></p>
<p><a name="sqlitedbconfigtriggereqp"></a>
<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></p>
<p><a name="sqlitedbconfigresetdatabase"></a>
<dt>SQLITE_DBCONFIG_RESET_DATABASE</dt>
<dd> Set the SQLITE_DBCONFIG_RESET_DATABASE flag and then run
<a href="../lang_vacuum.html">VACUUM</a> 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> <a href="../c3ref/exec.html">sqlite3_exec</a>(db, "<a href="../lang_vacuum.html">VACUUM</a>", 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. Because this
feature must be capable of resetting corrupt databases, and
shutting down virtual tables may require access to that corrupt
storage, the library must abandon any installed virtual tables
without calling their xDestroy() methods.</p>
<p><a name="sqlitedbconfigdefensive"></a>
<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 <a href="../pragma.html#pragma_writable_schema">PRAGMA writable_schema=ON</a> statement.
<li> The <a href="../pragma.html#pragma_journal_mode">PRAGMA journal_mode=OFF</a> statement.
<li> The <a href="../pragma.html#pragma_schema_version">PRAGMA schema_version=N</a> statement.
<li> Writes to the <a href="../dbpage.html">sqlite_dbpage</a> virtual table.
<li> Direct writes to <a href="../vtab.html#xshadowname">shadow tables</a>.
</ul>
</dd></p>
<p><a name="sqlitedbconfigwritableschema"></a>
<dt>SQLITE_DBCONFIG_WRITABLE_SCHEMA</dt>
<dd>The SQLITE_DBCONFIG_WRITABLE_SCHEMA option activates or deactivates the
"writable_schema" flag. This has the same effect and is logically equivalent
to setting <a href="../pragma.html#pragma_writable_schema">PRAGMA writable_schema=ON</a> or <a href="../pragma.html#pragma_writable_schema">PRAGMA writable_schema=OFF</a>.
The first argument to this setting is an integer which is 0 to disable
the writable_schema, positive to enable writable_schema, 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 writable_schema
is enabled or disabled following this call.
</dd></p>
<p><a name="sqlitedbconfiglegacyaltertable"></a>
<dt>SQLITE_DBCONFIG_LEGACY_ALTER_TABLE</dt>
<dd>The SQLITE_DBCONFIG_LEGACY_ALTER_TABLE option activates or deactivates
the legacy behavior of the <a href="../lang_altertable.html#altertabrename">ALTER TABLE RENAME</a> command such it
behaves as it did prior to <a href="../releaselog/3_24_0.html">version 3.24.0</a> (2018-06-04). See the
"Compatibility Notice" on the <a href="../lang_altertable.html#altertabrename">ALTER TABLE RENAME documentation</a> for
additional information. This feature can also be turned on and off
using the <a href="../pragma.html#pragma_legacy_alter_table">PRAGMA legacy_alter_table</a> statement.
</dd></p>
<p><a name="sqlitedbconfigdqsdml"></a>
<dt>SQLITE_DBCONFIG_DQS_DML</dt>
<dd>The SQLITE_DBCONFIG_DQS_DML option activates or deactivates
the legacy <a href="../quirks.html#dblquote">double-quoted string literal</a> misfeature for DML statements
only, that is DELETE, INSERT, SELECT, and UPDATE statements. The
default value of this setting is determined by the <a href="../compile.html#dqs">-DSQLITE_DQS</a>
compile-time option.
</dd></p>
<p><a name="sqlitedbconfigdqsddl"></a>
<dt>SQLITE_DBCONFIG_DQS_DDL</dt>
<dd>The SQLITE_DBCONFIG_DQS option activates or deactivates
the legacy <a href="../quirks.html#dblquote">double-quoted string literal</a> misfeature for DDL statements,
such as CREATE TABLE and CREATE INDEX. The
default value of this setting is determined by the <a href="../compile.html#dqs">-DSQLITE_DQS</a>
compile-time option.
</dd></p>
<p><a name="sqlitedbconfigtrustedschema"></a>
<dt>SQLITE_DBCONFIG_TRUSTED_SCHEMA</dt>
<dd>The SQLITE_DBCONFIG_TRUSTED_SCHEMA option tells SQLite to
assume that database schemas are untainted by malicious content.
When the SQLITE_DBCONFIG_TRUSTED_SCHEMA option is disabled, SQLite
takes additional defensive steps to protect the application from harm
including:
<ul>
<li> Prohibit the use of SQL functions inside triggers, views,
CHECK constraints, DEFAULT clauses, expression indexes,
partial indexes, or generated columns
unless those functions are tagged with <a href="../c3ref/c_deterministic.html#sqliteinnocuous">SQLITE_INNOCUOUS</a>.
<li> Prohibit the use of virtual tables inside of triggers or views
unless those virtual tables are tagged with <a href="../c3ref/c_vtab_constraint_support.html#sqlitevtabinnocuous">SQLITE_VTAB_INNOCUOUS</a>.
</ul>
This setting defaults to "on" for legacy compatibility, however
all applications are advised to turn it off if possible. This setting
can also be controlled using the <a href="../pragma.html#pragma_trusted_schema">PRAGMA trusted_schema</a> statement.
</dd></p>
<p><a name="sqlitedbconfiglegacyfileformat"></a>
<dt>SQLITE_DBCONFIG_LEGACY_FILE_FORMAT</dt>
<dd>The SQLITE_DBCONFIG_LEGACY_FILE_FORMAT option activates or deactivates
the legacy file format flag. When activated, this flag causes all newly
created database file to have a schema format version number (the 4-byte
integer found at offset 44 into the database header) of 1. This in turn
means that the resulting database file will be readable and writable by
any SQLite version back to 3.0.0 (2004-06-18). Without this setting,
newly created databases are generally not understandable by SQLite versions
prior to 3.3.0 (2006-01-11). As these words are written, there
is now scarcely any need to generate database files that are compatible
all the way back to version 3.0.0, and so this setting is of little
practical use, but is provided so that SQLite can continue to claim the
ability to generate new database files that are compatible with version
3.0.0.
<p>Note that when the SQLITE_DBCONFIG_LEGACY_FILE_FORMAT setting is on,
the <a href="../lang_vacuum.html">VACUUM</a> command will fail with an obscure error when attempting to
process a table with generated columns and a descending index. This is
not considered a bug since SQLite versions 3.3.0 and earlier do not support
either generated columns or descending indexes.
</dd></p>
<p><a name="sqlitedbconfigstmtscanstatus"></a>
<dt>SQLITE_DBCONFIG_STMT_SCANSTATUS</dt>
<dd>The SQLITE_DBCONFIG_STMT_SCANSTATUS option is only useful in
SQLITE_ENABLE_STMT_SCANSTATUS builds. In this case, it sets or clears
a flag that enables collection of the sqlite3_stmt_scanstatus_v2()
statistics. For statistics to be collected, the flag must be set on
the database handle both when the SQL statement is prepared and when it
is stepped. The flag is set (collection of statistics is enabled)
by default. This option takes two arguments: an integer and a pointer to
an integer.. The first argument is 1, 0, or -1 to enable, disable, or
leave unchanged the statement scanstatus option. If the second argument
is not NULL, then the value of the statement scanstatus setting after
processing the first argument is written into the integer that the second
argument points to.
</dd></p>
<p><a name="sqlitedbconfigreversescanorder"></a>
<dt>SQLITE_DBCONFIG_REVERSE_SCANORDER</dt>
<dd>The SQLITE_DBCONFIG_REVERSE_SCANORDER option changes the default order
in which tables and indexes are scanned so that the scans start at the end
and work toward the beginning rather than starting at the beginning and
working toward the end. Setting SQLITE_DBCONFIG_REVERSE_SCANORDER is the
same as setting <a href="../pragma.html#pragma_reverse_unordered_selects">PRAGMA reverse_unordered_selects</a>. This option takes
two arguments which are an integer and a pointer to an integer. The first
argument is 1, 0, or -1 to enable, disable, or leave unchanged the
reverse scan order flag, respectively. If the second argument is not NULL,
then 0 or 1 is written into the integer that the second argument points to
depending on if the reverse scan order flag is set after processing the
first argument.
</dd></p>
<p></dl>
</p><p>See also lists of
<a href="../c3ref/objlist.html">Objects</a>,
<a href="../c3ref/constlist.html">Constants</a>, and
<a href="../c3ref/funclist.html">Functions</a>.</p>
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