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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_WRITABLE_SCHEMA, SQLITE_DBCONFIG_LEGACY_ALTER_TABLE,
SQLITE_DBCONFIG_DQS_DML, SQLITE_DBCONFIG_DQS_DDL,
SQLITE_DBCONFIG_ENABLE_VIEW, SQLITE_DBCONFIG_LEGACY_FILE_FORMAT,
SQLITE_DBCONFIG_TRUSTED_SCHEMA, SQLITE_DBCONFIG_STMT_SCANSTATUS,
SQLITE_DBCONFIG_REVERSE_SCANORDER, SQLITE_DBCONFIG_MAX - database
connection configuration options
SYNOPSIS
#include <sqlite3.h>
#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_WRITABLE_SCHEMA
#define SQLITE_DBCONFIG_LEGACY_ALTER_TABLE
#define SQLITE_DBCONFIG_DQS_DML
#define SQLITE_DBCONFIG_DQS_DDL
#define SQLITE_DBCONFIG_ENABLE_VIEW
#define SQLITE_DBCONFIG_LEGACY_FILE_FORMAT
#define SQLITE_DBCONFIG_TRUSTED_SCHEMA
#define SQLITE_DBCONFIG_STMT_SCANSTATUS
#define SQLITE_DBCONFIG_REVERSE_SCANORDER
#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_DBSTATUS_LOOKASIDE_USED,...) 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.
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.
SQLITE_DBCONFIG_ENABLE_VIEW
This option is used to enable or disable views. 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.
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.
SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER
This option is used to enable or disable 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. 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.
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.
⊕ The PRAGMA journal_mode=OFF statement.
⊕ The PRAGMA schema_version=N statement.
⊕ Writes to the sqlite_dbpage virtual table.
⊕ Direct writes to shadow tables.
SQLITE_DBCONFIG_WRITABLE_SCHEMA
The SQLITE_DBCONFIG_WRITABLE_SCHEMA option activates or
deactivates the "writable_schema" flag. This has the same effect
and is logically equivalent to setting PRAGMA writable_schema=ON
or PRAGMA writable_schema=OFF. 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.
SQLITE_DBCONFIG_LEGACY_ALTER_TABLE
The SQLITE_DBCONFIG_LEGACY_ALTER_TABLE option activates or
deactivates the legacy behavior of the ALTER TABLE RENAME command
such it behaves as it did prior to version 3.24.0 (2018-06-04).
See the "Compatibility Notice" on the ALTER TABLE RENAME
documentation for additional information. This feature can also
be turned on and off using the PRAGMA legacy_alter_table
statement.
SQLITE_DBCONFIG_DQS_DML
The SQLITE_DBCONFIG_DQS_DML option activates or deactivates the
legacy double-quoted string literal misfeature for DML statements
only, that is DELETE, INSERT, SELECT, and UPDATE statements. The
default value of this setting is determined by the -DSQLITE_DQS
compile-time option.
SQLITE_DBCONFIG_DQS_DDL
The SQLITE_DBCONFIG_DQS option activates or deactivates the
legacy double-quoted string literal misfeature for DDL
statements, such as CREATE TABLE and CREATE INDEX. The default
value of this setting is determined by the -DSQLITE_DQS compile-
time option.
SQLITE_DBCONFIG_TRUSTED_SCHEMA
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:
⊕ 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 SQLITE_INNOCUOUS.
⊕ Prohibit the use of virtual tables inside of triggers or
views unless those virtual tables are tagged with
SQLITE_VTAB_INNOCUOUS.
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 PRAGMA trusted_schema
statement.
SQLITE_DBCONFIG_LEGACY_FILE_FORMAT
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 (dateof:3.0.0). Without this setting, newly
created databases are generally not understandable by SQLite
versions prior to 3.3.0 (dateof:3.3.0). 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.
Note that when the SQLITE_DBCONFIG_LEGACY_FILE_FORMAT setting is
on, the VACUUM 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.
SQLITE_DBCONFIG_STMT_SCANSTATUS
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.
SQLITE_DBCONFIG_REVERSE_SCANORDER
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 PRAGMA
reverse_unordered_selects. 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.
IMPLEMENTATION NOTES
These declarations were extracted from the interface documentation at
line 2177.
#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 */
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_DBSTATUS_LOOKASIDE_USED(3), SQLITE_DETERMINISTIC(3), SQLITE_OK(3),
SQLITE_VTAB_CONSTRAINT_SUPPORT(3)
NetBSD 10.99 August 24, 2023 NetBSD 10.99