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<title>Compilation Options For SQLite</title>

<h1>1.0 Compilation Options For SQLite</h1>

<p>
For most purposes, SQLite can be built just fine using the default
compilation options. However, if required, the compile-time options
documented below can be used to 
<a href="#omitfeatures">omit SQLite features</a> (resulting in
a smaller compiled library size) or to change the
<a href="#defaults">default values</a> of some parameters.
</p>

<p>
Every effort has been made to ensure that the various combinations
of compilation options work harmoniously and produce a working library.
Nevertheless, it is strongly recommended that the SQLite test-suite
be executed to check for errors before using an SQLite library built
with non-standard compilation options.
</p>
<a name="defaults"></a>
<h2>1.1 Options To Set Default Parameter Values</h2>

<tcl>
proc COMPILE_OPTION {name text} {
  if {[regexp {SQLITE_([A-Z0-9_]+)} $name all label]} {
    hd_fragment [string tolower $label]
    hd_keywords $all
  }
  if {[regexp {^YY([A-Z0-9_]+)} $name all label]} {
    hd_fragment [string tolower $all]
    hd_keywords $all
  }
  hd_puts <p><b>$name</b></p>
  regsub -all "\n\\s*\n" $text "</p>\n\n<p>" text
  hd_resolve <blockquote><p>$text</p></blockquote>
}

COMPILE_OPTION {SQLITE_DEFAULT_AUTOVACUUM=<i>&lt;1 or 0&gt;</i>} {
  This macro determines if SQLite creates databases with the 
  [auto_vacuum] flag set by default. The default value is 0 
  (do not create auto-vacuum databases). In any case the
  compile-time default may be overridden by the 
  [PRAGMA auto_vacuum] command.
}

COMPILE_OPTION {SQLITE_DEFAULT_CACHE_SIZE=<i>&lt;pages&gt;</i>} {
  This macro sets the default size of the page-cache for each attached
  database, in pages. This can be overridden by the 
  [PRAGMA cache_size] comamnd. The default value is 2000.
}

COMPILE_OPTION {SQLITE_DEFAULT_FILE_FORMAT=<i>&lt;1 or 4&gt;</i>} {
  The default schema-level file format used by SQLite when creating
  new database files is set by this macro.  The file formats are all
  very similar.  The difference between formats 1 and 4 is that format
  4 understands descending indices and has a tighter encoding for
  boolean values.

  SQLite (as of [version 3.6.0]) can read and write any file format
  between 1 and 4.  But older versions of SQLite might not be able to
  read formats greater than 1.  So that older versions of SQLite will
  be able to read and write database files created by newer versions
  of SQLite, the default file format is set to 1 for maximum
  compatability.

  The file format for a new database can be set at runtime using
  the [PRAGMA legacy_file_format] command.
}

COMPILE_OPTION {SQLITE_DEFAULT_PAGE_SIZE=<i>&lt;bytes&gt;</i>} {
  This macro is used to set the default page-size used when a
  database is created. The value assigned must be a power of 2. The
  default value is 1024. The compile-time default may be overridden at 
  runtime by the [PRAGMA page_size] command.
}

COMPILE_OPTION {SQLITE_DEFAULT_TEMP_CACHE_SIZE=<i>&lt;pages&gt;</i>} {
  This macro sets the default size of the page-cache for temporary files
  created by SQLite to store intermediate results, in pages. It does
  not affect the page-cache for the temp database, where tables created
  using [CREATE TABLE | CREATE TEMP TABLE] are stored. The default value
  is 500.
}

COMPILE_OPTION {YYSTACKDEPTH=<i>&lt;max_depth&gt;</i>} {
  This macro sets the maximum depth of the LALR(1) stack used by
  the SQL parser within SQLite.  The default value is 100.  A typical
  application will use less than about 20 levels of the stack.
  Developers whose applications contain SQL statements that 
  need more than 100 LALR(1) stack entries should seriously
  consider refactoring their SQL as it is likely to be well beyond
  the ability of any human to comprehend.
}
</tcl>

<h2>1.2 Options To Set Size Limits</h2>

<p>There are compile-time options that will set upper bounds
on the sizes of various structures in SQLite.  The compile-time
options normally set a hard upper bound which can be changed
at run-time on individual [database connections] using the
[sqlite3_limit()] interface.</p>

<p>The compile-time options for setting upper bounds are
[limits | documented separately].  The following is a list of
the available settings:</p>

<ul>
<li> [SQLITE_MAX_ATTACHED]  </li>
<li> [SQLITE_MAX_COLUMN]  </li>
<li> [SQLITE_MAX_COMPOUND_SELECT]  </li>
<li> [SQLITE_MAX_EXPR_DEPTH]  </li>
<li> [SQLITE_MAX_FUNCTION_ARG]  </li>
<li> [SQLITE_MAX_LENGTH]  </li>
<li> [SQLITE_MAX_LIKE_PATTERN_LENGTH]  </li>
<li> [SQLITE_MAX_PAGE_COUNT]  </li>
<li> [SQLITE_MAX_PAGE_SIZE]  </li>
<li> [SQLITE_MAX_SQL_LENGTH]  </li>
<li> [SQLITE_MAX_VARIABLE_NUMBER]  </li>
</ul>

<a name="controlfeatures"></a>
<h2>1.3 Options To Control Operating Characteristics</h2>

<tcl>
COMPILE_OPTION {SQLITE_SECURE_DELETE} {
  This compile-time option causes SQLite to overwrite deleted
  information with zeros in addition to marking the space
  as available for reuse.  Without this option, deleted data
  might be recoverable from a database using a binary editor.
  However, there is a performance penalty for using this option.

  This option does <u>not</u> cause deleted data is securely
  removed from the underlying storage media.
}

COMPILE_OPTION {SQLITE_THREADSAFE=<i>&lt;0 or 1&gt;</i>} {
  This option controls whether or not code is included in SQLite to
  enable it to operate safely in a multithreaded environment.  The
  default is SQLITE_THREADSAFE=1 which is safe for use in a multithreaded
  environment.  When compiled with SQLITE_THREADSAFE=0 all mutexing code
  is omitted and it is unsafe to use SQLite in a multithreaded program.

  The value of SQLITE_THREADSAFE can be determined at run-time
  using the [sqlite3_threadsafe()] interface.

  When SQLite has been compiled with SQLITE_THREADSAFE=1 then mutexing
  can be disabled at run-time using the [sqlite3_config()] interface together
  with the [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD], and
  [SQLITE_CONFIG_SERIALIZED] verbs.
}

COMPILE_OPTION {SQLITE_TEMP_STORE=<i>&lt;0 through 3&gt;</i>} {
  This option controls whether temporary files are stored on disk or
  in memory.  The meanings for various settings of this compile-time
  option are as follows:

  <table cellpadding="2" border="1">
  <tr><th>SQLITE_TEMP_STORE</th><th>Meaning</th></tr>
  <tr><td align="center">0</td><td>Always use temporary files</td></tr>
  <tr><td align="center">1</td><td>Use files by default but allow the
  [PRAGMA temp_store] command to override</td></tr>
  <tr><td align="center">2</td><td>Use memory by default but allow the
  [PRAGMA temp_store] command to override</td></tr>
  <tr><td align="center">3</td><td>Always use memory</td></tr>
  </table>

  The default setting is 1.  
  Additional information can be found in [tempstore | tempfiles.html].
}
</tcl>

<a name="enablefeatures"></a>
<h2>1.4 Options To Enable Features Normally Turned Off</h2>

<tcl>
COMPILE_OPTION {SQLITE_ENABLE_ATOMIC_WRITE} {
  If this C-preprocessor macro is defined and if the
  xDeviceCharacteristics method of [sqlite3_io_methods] object for
  a database file reports (via one of the [SQLITE_IOCAP_ATOMIC] bits)
  that the filesystem supports atomic writes and if a transaction
  involves a change to only a single page of the database file,
  then the transaction commits with just a single write request of
  a single page of the database and no rollback journal is created
  or written.  On filesystems that support atomic writes, this
  optimization can result in significant speed improvements for
  small updates.  However, few filesystems support this capability
  and the code paths that check for this capability slow down write
  performance on systems that lack atomic write capability, so this
  feature is disabled by default.
}

COMPILE_OPTION {SQLITE_ENABLE_COLUMN_METADATA} {
  When this C-preprocessor macro is defined, SQLite includes some
  additional APIs that provide convenient access to meta-data about
  tables and queries.  The APIs that are enabled by this option are:

  <ul>
  <li> [sqlite3_column_database_name()] </li>
  <li> [sqlite3_column_database_name16()] </li>
  <li> [sqlite3_column_table_name()] </li>
  <li> [sqlite3_column_table_name16()] </li>
  <li> [sqlite3_column_origin_name()] </li>
  <li> [sqlite3_column_origin_name16()] </li>
  <li> [sqlite3_table_column_metadata()] </li>
  </ul>
}

COMPILE_OPTION {SQLITE_ENABLE_FTS3} {
  When this option is defined in the [amalgamation], version 3
  of the full-text search engine is added to the build automatically.
}

COMPILE_OPTION {SQLITE_ENABLE_ICU} {
  This option causes the 
  <a href="http://www.icu-project.org/">International Components for Unicode</a>
  or "ICU" extension to SQLite to be added to the build.  
}

COMPILE_OPTION {SQLITE_ENABLE_IOTRACE} {
  When both the SQLite core and the [Command Line Interface] (CLI) are both 
  compiled with this option, then the CLI provides an extra command
  named ".iotrace" that provides a low-level log of I/O activity.
  This option is experimental and may be discontinued in a future release.
}

COMPILE_OPTION {SQLITE_ENABLE_LOCKING_STYLE} {
  This option enables additional logic in the OS interface layer for
  Mac OS X.  The additional logic attempts to determine the type of the
  underlying filesystem and choose and alternative locking strategy
  that works correctly for that filesystem type.
}

COMPILE_OPTION {SQLITE_ENABLE_MEMORY_MANAGEMENT} {
  This option adds extra logic to SQLite that allows it to release unused
  memory upon request.  This option must be enabled in order for the
  [sqlite3_release_memory()] interface to work.  If this compile-time
  option is not used, the [sqlite3_release_memory()] interface is a 
  no-op.  Since [sqlite3_soft_heap_limit()] depends on
  [sqlite3_release_memory()], this option is also necessary for
  the correct operation of [sqlite3_soft_heap_limit()].
}

COMPILE_OPTION {SQLITE_ENABLE_MEMSYS3} {
  This option includes code in SQLite that implements an alternative
  memory allocator.  This alternative memory allocator is only engaged
  when the [SQLITE_CONFIG_HEAP] option to [sqlite3_config()] is used to
  supply a large chunk of memory from which all memory allocations are
  taken.
  The MEMSYS3 memory allocator uses a hybrid allocation algorithm 
  patterned after dlmalloc().   Only one of SQLITE_ENABLE_MEMSYS3 and 
  SQLITE_ENABLE_MEMSYS5 may be enabled at once.
}

COMPILE_OPTION {SQLITE_ENABLE_MEMSYS5} {
  This option includes code in SQLite that implements an alternative
  memory allocator.  This alternative memory allocator is only engaged
  when the [SQLITE_CONFIG_HEAP] option to [sqlite3_config()] is used to
  supply a large chunk of memory from which all memory allocations are
  taken.
  The MEMSYS5 module rounds all allocations up to the next power
  of two and uses a first-fit, buddy-allocator algorithm
  that provides strong guarantees against fragmentation and breakdown
  subject to certain operating constraints.
}

COMPILE_OPTION {SQLITE_ENABLE_RTREE} {
  This option causes SQLite to include support for the
  [rtree | R*Tree index extension].
}

COMPILE_OPTION {YYTRACKMAXSTACKDEPTH} {
  This option causes the LALR(1) parser stack depth to be tracked
  and reported using the [sqlite3_status]([SQLITE_STATUS_PARSER_STACK],...)
  interface.  SQLite's LALR(1) parser has a fixed stack depth
  (determined at compile-time using the [YYSTACKDEPTH] options).
  This option can be used to help determine if an application is
  getting close to exceeding the maximum LALR(1) stack depth.
}
</tcl>

<a name="omitfeatures"></a>
<h2>1.5 Options To Omit Features</h2>

<p>The following options can used to reduce the size of the compiled
library by omitting optional features. This is probably only useful
in embedded systems where space is especially tight, as even with all
features included the SQLite library is relatively small. Don't forget
to tell your compiler to optimize for binary size! (the -Os option if
using GCC).  Telling your compiler to optimize for size usually has
a much large impact on library footprint than employing any of these
compile-time options.</p>

<p>The macros in this section do not require values. The following 
compilation switches all have the same effect:<br>
-DSQLITE_OMIT_ALTERTABLE<br>
-DSQLITE_OMIT_ALTERTABLE=1<br>
-DSQLITE_OMIT_ALTERTABLE=0
</p>

<p>If any of these options are defined, then the same set of SQLITE_OMIT_XXX
options must also be defined when using the 'lemon' tool to generate a parse.c
file. Because of this, these options may only be used when the library is built
from source, not from the [amalgamation] or from the collection of
pre-packaged C files provided for non-UNIX like platforms on the website.
</p>

<p>These "OMIT" options are considered unsupported.  Any of these
options may be removed from the code in a future release
and without warning.  For any particular release, some of these
options may cause compile-time or run-time failures.</p>

<tcl>
COMPILE_OPTION {SQLITE_OMIT_ALTERTABLE} {
  When this option is defined, the 
  [ALTER TABLE] command is not included in the 
  library. Executing an [ALTER TABLE] statement causes a parse error.
}

COMPILE_OPTION {SQLITE_OMIT_ANALYZE} {
  When this option is defined, the [ANALYZE] command is omitted from
  the build.
}

COMPILE_OPTION {SQLITE_OMIT_ATTACH} {
  When this option is defined, the [ATTACH] and [DETACH] commands are
  omitted from the build.
}

COMPILE_OPTION {SQLITE_OMIT_AUTHORIZATION} {
  Defining this option omits the authorization callback feature from the
  library. The [sqlite3_set_authorizer()] API function is not present
  in the library.
}

COMPILE_OPTION {SQLITE_OMIT_AUTOINCREMENT} {
  This option is used to omit the 
  [AUTOINCREMENT] functionality. When this 
  is macro is defined, columns declared as 
  "[INTEGER PRIMARY KEY] AUTOINCREMENT"
  behave in the same way as columns declared as "[INTEGER PRIMARY KEY]" when a 
  NULL is inserted. The sqlite_sequence system table is neither created, nor
  respected if it already exists.
}

COMPILE_OPTION {SQLITE_OMIT_AUTOINIT} {
  For backwards compatibility with older versions of SQLite that lack
  the [sqlite3_initialize()] interface, the [sqlite3_initialize()] interface
  is called automatically upon entry to certain key interfaces such as
  [sqlite3_open()], [sqlite3_vfs_register()], and [sqlite3_mprintf()].
  The overhead of invoking [sqlite3_initialize()] automatically in this
  way may be omitted by building SQLite with the SQLITE_OMIT_AUTOINIT
  C-preprocessor macro.  When built using SQLITE_OMIT_AUTOINIT, SQLite
  will not automatically initialize itself and the application is required
  to invoke [sqlite3_initialize()] directly prior to beginning use of the
  SQLite library.
}

COMPILE_OPTION {SQLITE_OMIT_AUTOVACUUM} {
  If this option is defined, the library cannot create or write to 
  databases that support [auto_vacuum].
  Executing a [PRAGMA auto_vacuum] statement is not an error
  (since unknown PRAGMAs are silently ignored), but does not return a value
  or modify the auto-vacuum flag in the database file. If a database that
  supports auto-vacuum is opened by a library compiled with this option, it
  is automatically opened in read-only mode.
}

COMPILE_OPTION {SQLITE_OMIT_BETWEEN_OPTIMIZATION} {
  This option disables the use of indices with WHERE clause terms
  that employ the BETWEEN operator.
}

COMPILE_OPTION {SQLITE_OMIT_BLOB_LITERAL} {
  When this option is defined, it is not possible to specify a blob in
  an SQL statement using the X'ABCD' syntax.
}

COMPILE_OPTION {SQLITE_OMIT_BUILTIN_TEST} {
  A standard SQLite build includes a small amount of logic controlled
  by the [sqlite3_test_control()] interface that is used to exercise
  parts of the SQLite core that are difficult to control and measure using
  the standard API.  This option omits that built-in test logic.
}

COMPILE_OPTION {SQLITE_OMIT_CAST} {
  This option causes SQLite to omit support for the CAST operator.
}

COMPILE_OPTION {SQLITE_OMIT_CHECK} {
  This option causes SQLite to omit support for CHECK constraints.
}

COMPILE_OPTION {SQLITE_OMIT_COMPLETE} {
  This option causes the [sqlite3_complete()] and [sqlite3_complete16()]
  interfaces to be omitted.
}

COMPILE_OPTION {SQLITE_OMIT_COMPOUND_SELECT} {
  This option is used to omit the compound [SELECT] functionality. 
  [SELECT] statements that use the 
  UNION, UNION ALL, INTERSECT or EXCEPT compound SELECT operators will 
  cause a parse error.
}

COMPILE_OPTION {SQLITE_OMIT_CONFLICT_CLAUSE} {
  In the future, this option will be used to omit the 
  [ON CONFLICT] clause from the library.
}

COMPILE_OPTION {SQLITE_OMIT_DATETIME_FUNCS} {
  If this option is defined, SQLite's built-in date and time manipulation
  functions are omitted. Specifically, the SQL functions julianday(), date(),
  time(), datetime() and strftime() are not available. The default column
  values CURRENT_TIME, CURRENT_DATE and CURRENT_DATETIME are still available.
}

COMPILE_OPTION {SQLITE_OMIT_DECLTYPE} {
  This option causes SQLite to omit support for the
  [sqlite3_column_decltype()] and [sqlite3_column_decltype16()]
  interfaces.
}

COMPILE_OPTION {SQLITE_OMIT_DISKIO} {
  This option omits all support for writing to the disk and forces
  databases to exist in memory only.
}

COMPILE_OPTION {SQLITE_OMIT_EXPLAIN} {
  Defining this option causes the [EXPLAIN] command to be omitted from the
  library. Attempting to execute an [EXPLAIN] statement will cause a parse
  error.
}

COMPILE_OPTION {SQLITE_OMIT_FLAG_PRAGMAS} {
  This option omits support for a subset of [PRAGMA] commands that
  query and set boolean properties.
}

COMPILE_OPTION {SQLITE_OMIT_FLOATING_POINT} {
  This option is used to omit floating-point number support from the SQLite
  library. When specified, specifying a floating point number as a literal 
  (i.e. "1.01") results in a parse error.

  <p>In the future, this option may also disable other floating point 
  functionality, for example the [sqlite3_result_double()], 
  [sqlite3_bind_double()], [sqlite3_value_double()] and
  [sqlite3_column_double()] API functions.
  </p>
}

COMPILE_OPTION {SQLITE_OMIT_FOREIGN_KEY} {
  If this option is defined, FOREIGN KEY clauses in column declarations are
  ignored.
}

COMPILE_OPTION {SQLITE_OMIT_GET_TABLE} {
  This option causes support for [sqlite3_get_table()] and
  [sqlite3_free_table()] to be omitted.
}

COMPILE_OPTION {SQLITE_OMIT_INCRBLOB} {
  This option causes support for [sqlite3_blob | incremental BLOB I/O]
  to be omitted.
}

COMPILE_OPTION {SQLITE_OMIT_INTEGRITY_CHECK} {
  This option omits support for the [integrity_check pragma].
}

COMPILE_OPTION {SQLITE_OMIT_LIKE_OPTIMIZATION} {
  This option disable the ability of SQLite to use indices to help
  resolve [LIKE] and [GLOB] operators in a WHERE clause.
}

COMPILE_OPTION {SQLITE_OMIT_LOAD_EXTENSION} {
  This option omits the entire extension loading mechanism from
  SQLite, including [sqlite3_enable_load_extension()] and
  [sqlite3_load_extension()] interfaces.
}

COMPILE_OPTION {SQLITE_OMIT_LOCALTIME} {
  This option omits the "localtime" modifier from the date and time
  functions.  This option is sometimes useful when trying to compile
  the date and time functions on a platform that does not support the
  concept of local time.
}

COMPILE_OPTION {SQLITE_OMIT_MEMORYDB} {
  When this is defined, the library does not respect the special database
  name ":memory:" (normally used to create an in-memory database). If 
  ":memory:" is passed to [sqlite3_open()], [sqlite3_open16()], or
  [sqlite3_open_v2()], a file with this name will be 
  opened or created.
}

COMPILE_OPTION {SQLITE_OMIT_OR_OPTIMIZATION} {
  This option disables the ability of SQLite to use an index together
  with terms of a WHERE clause connected by the OR operator.
}

COMPILE_OPTION {SQLITE_OMIT_PAGER_PRAGMAS} {
  Defining this option omits pragmas related to the pager subsystem from 
  the build.
}

COMPILE_OPTION {SQLITE_OMIT_PRAGMA} {
  This option is used to omit the [PRAGMA] command
  from the library. Note that it is useful to define the macros that omit
  specific pragmas in addition to this, as they may also remove supporting code
  in other sub-systems. This macro removes the [PRAGMA] command only.
}

COMPILE_OPTION {SQLITE_OMIT_PROGRESS_CALLBACK} {
  This option may be defined to omit the capability to issue "progress" 
  callbacks during long-running SQL statements. The 
  [sqlite3_progress_handler()]
  API function is not present in the library.
}

COMPILE_OPTION {SQLITE_OMIT_QUICKBALANCE} {
  This option omits an alternative, faster B-Tree balancing routine.
  Using this option makes SQLite slightly smaller at the expense of
  making it run slightly slower.
}

COMPILE_OPTION {SQLITE_OMIT_REINDEX} {
  When this option is defined, the [REINDEX]
  command is not included in the library.
  Executing a [REINDEX] statement causes 
  a parse error.
}

COMPILE_OPTION {SQLITE_OMIT_SCHEMA_PRAGMAS} {
  Defining this option omits pragmas for querying the database schema from 
  the build.
}

COMPILE_OPTION {SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS} {
  Defining this option omits pragmas for querying and modifying the 
  database schema version and user version from the build. Specifically, the 
  [schema_version] and [user_version] PRAGMAs are omitted.
}

COMPILE_OPTION {SQLITE_OMIT_SHARED_CACHE} {
  This option builds SQLite without support for shared-cache mode.
  The [sqlite3_enable_shared_cache()] is omitted along with a fair
  amount of logic within the B-Tree subsystem associated with shared
  cache management.
}

COMPILE_OPTION {SQLITE_OMIT_SUBQUERY} {
  If defined, support for sub-selects and the IN() operator are omitted.
}

COMPILE_OPTION {SQLITE_OMIT_TCL_VARIABLE} {
  If this macro is defined, then the special "$<variable-name>" syntax
  used to automatically bind SQL variables to TCL variables is omitted.
}

COMPILE_OPTION {SQLITE_OMIT_TEMPDB} {
  This option omits support for TEMP or TEMPORARY tables.
}

COMPILE_OPTION {SQLITE_OMIT_TRACE} {
  This option omits support for the [sqlite3_profile()] and
  [sqlite3_trace()] interfaces and their associated logic.
}

COMPILE_OPTION {SQLITE_OMIT_TRIGGER} {
  Defining this option omits support for VIEW objects. Neither the 
  [CREATE TRIGGER] or [DROP TRIGGER]
  commands are available in this case, and attempting to execute
  either will result in a parse error.

  WARNING: If this macro is defined, it will not be possible to open a database
  for which the schema contains TRIGGER objects. 
}

COMPILE_OPTION {SQLITE_OMIT_UTF16} {
  This macro is used to omit support for UTF16 text encoding. When this is
  defined all API functions that return or accept UTF16 encoded text are
  unavailable. These functions can be identified by the fact that they end
  with '16', for example [sqlite3_prepare16()], [sqlite3_column_text16()] and
  [sqlite3_bind_text16()].
}

COMPILE_OPTION {SQLITE_OMIT_VACUUM} {
  When this option is defined, the [VACUUM]
  command is not included in the library.
  Executing a [VACUUM] statement causes 
  a parse error.
}

COMPILE_OPTION {SQLITE_OMIT_VIEW} {
  Defining this option omits support for VIEW objects. Neither the 
  [CREATE VIEW] nor the [DROP VIEW]
  commands are available in this case, and
  attempting to execute either will result in a parse error.

  WARNING: If this macro is defined, it will not be possible to open a database
  for which the schema contains VIEW objects. 
}

COMPILE_OPTION {SQLITE_OMIT_VIRTUALTABLE} {
  This option omits support for the [sqlite3_vtab | Virtual Table]
  mechanism in SQLite.
}

COMPILE_OPTION {SQLITE_OMIT_XFER_OPT} {
  This option omits support for optimizations that help statements
  of the form "INSERT INTO ... SELECT ..." run faster.
}

</tcl>
<a name="omitfeatures"></a>
<h2>1.6 Analysis and Debugging Options</h2>
<tcl>

COMPILE_OPTION {SQLITE_DEBUG} {
  The SQLite source code contains literally thousands of assert() statements
  used to verify internal assumptions and subroutine preconditions and
  postconditions.  These assert() statements are normally turned off
  (they generate no code) since turning them on makes SQLite run approximately
  three times slower.  But for testing and analysis, it is useful to turn
  the assert() statements on.  The SQLITE_DEBUG compile-time option does this.
  SQLITE_DEBUG also turns on some other debugging features.
}

COMPILE_OPTION {SQLITE_MEMDEBUG} {
  The SQLITE_MEMDEBUG option causes an instrumented dynamic memory allocator
  to be used as the default memory allocator within SQLite.  The
  instrumented memory allocator checks for misuse of dynamically allocated
  memory.  Examples of misuse include using memory after it is freed,
  writing off the ends of a memory allocation, freeing memory not previously
  obtained from the memory allocator, or failing to initialize newly
  allocated memory.
}

</tcl>