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<!-- keywords: {SQLITE_DBSTATUS options} SQLITE_DBSTATUS_CACHE_HIT SQLITE_DBSTATUS_CACHE_MISS SQLITE_DBSTATUS_CACHE_SPILL SQLITE_DBSTATUS_CACHE_USED SQLITE_DBSTATUS_CACHE_USED_SHARED SQLITE_DBSTATUS_CACHE_WRITE SQLITE_DBSTATUS_DEFERRED_FKS SQLITE_DBSTATUS_LOOKASIDE_HIT SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE SQLITE_DBSTATUS_LOOKASIDE_USED SQLITE_DBSTATUS_MAX SQLITE_DBSTATUS_SCHEMA_USED SQLITE_DBSTATUS_STMT_USED -->
<div class=nosearch>
<a href="../c3ref/intro.html"><h2>SQLite C Interface</h2></a>
<h2>Status Parameters for database connections</h2>
</div>
<blockquote><pre>
#define SQLITE_DBSTATUS_LOOKASIDE_USED 0
#define SQLITE_DBSTATUS_CACHE_USED 1
#define SQLITE_DBSTATUS_SCHEMA_USED 2
#define SQLITE_DBSTATUS_STMT_USED 3
#define SQLITE_DBSTATUS_LOOKASIDE_HIT 4
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE 5
#define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL 6
#define SQLITE_DBSTATUS_CACHE_HIT 7
#define SQLITE_DBSTATUS_CACHE_MISS 8
#define SQLITE_DBSTATUS_CACHE_WRITE 9
#define SQLITE_DBSTATUS_DEFERRED_FKS 10
#define SQLITE_DBSTATUS_CACHE_USED_SHARED 11
#define SQLITE_DBSTATUS_CACHE_SPILL 12
#define SQLITE_DBSTATUS_MAX 12 /* Largest defined DBSTATUS */
</pre></blockquote>
<p>
These constants are the available integer "verbs" that can be passed as
the second argument to the <a href="../c3ref/db_status.html">sqlite3_db_status()</a> interface.</p>
<p>New verbs may be added in future releases of SQLite. Existing verbs
might be discontinued. Applications should check the return code from
<a href="../c3ref/db_status.html">sqlite3_db_status()</a> to make sure that the call worked.
The <a href="../c3ref/db_status.html">sqlite3_db_status()</a> interface will return a non-zero error code
if a discontinued or unsupported verb is invoked.</p>
<p><dl>
<a name="sqlitedbstatuslookasideused"></a>
<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
<dd>This parameter returns the number of lookaside memory slots currently
checked out.</dd></p>
<p><a name="sqlitedbstatuslookasidehit"></a>
<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt>
<dd>This parameter returns the number of malloc attempts that were
satisfied using lookaside memory. Only the high-water value is meaningful;
the current value is always zero.</p>
<p><a name="sqlitedbstatuslookasidemisssize"></a>
<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt>
<dd>This parameter returns the number malloc attempts that might have
been satisfied using lookaside memory but failed due to the amount of
memory requested being larger than the lookaside slot size.
Only the high-water value is meaningful;
the current value is always zero.</p>
<p><a name="sqlitedbstatuslookasidemissfull"></a>
<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt>
<dd>This parameter returns the number malloc attempts that might have
been satisfied using lookaside memory but failed due to all lookaside
memory already being in use.
Only the high-water value is meaningful;
the current value is always zero.</p>
<p><a name="sqlitedbstatuscacheused"></a>
<dt>SQLITE_DBSTATUS_CACHE_USED</dt>
<dd>This parameter returns the approximate number of bytes of heap
memory used by all pager caches associated with the database connection.
The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.</p>
<p><a name="sqlitedbstatuscacheusedshared"></a>
<dt>SQLITE_DBSTATUS_CACHE_USED_SHARED</dt>
<dd>This parameter is similar to DBSTATUS_CACHE_USED, except that if a
pager cache is shared between two or more connections the bytes of heap
memory used by that pager cache is divided evenly between the attached
connections. In other words, if none of the pager caches associated
with the database connection are shared, this request returns the same
value as DBSTATUS_CACHE_USED. Or, if one or more or the pager caches are
shared, the value returned by this call will be smaller than that returned
by DBSTATUS_CACHE_USED. The highwater mark associated with
SQLITE_DBSTATUS_CACHE_USED_SHARED is always 0.</p>
<p><a name="sqlitedbstatusschemaused"></a>
<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
<dd>This parameter returns the approximate number of bytes of heap
memory used to store the schema for all databases associated
with the connection - main, temp, and any <a href="../lang_attach.html">ATTACH</a>-ed databases.
The full amount of memory used by the schemas is reported, even if the
schema memory is shared with other database connections due to
<a href="../sharedcache.html">shared cache mode</a> being enabled.
The highwater mark associated with SQLITE_DBSTATUS_SCHEMA_USED is always 0.</p>
<p><a name="sqlitedbstatusstmtused"></a>
<dt>SQLITE_DBSTATUS_STMT_USED</dt>
<dd>This parameter returns the approximate number of bytes of heap
and lookaside memory used by all prepared statements associated with
the database connection.
The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
</dd></p>
<p><a name="sqlitedbstatuscachehit"></a>
<dt>SQLITE_DBSTATUS_CACHE_HIT</dt>
<dd>This parameter returns the number of pager cache hits that have
occurred. The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT
is always 0.
</dd></p>
<p><a name="sqlitedbstatuscachemiss"></a>
<dt>SQLITE_DBSTATUS_CACHE_MISS</dt>
<dd>This parameter returns the number of pager cache misses that have
occurred. The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS
is always 0.
</dd></p>
<p><a name="sqlitedbstatuscachewrite"></a>
<dt>SQLITE_DBSTATUS_CACHE_WRITE</dt>
<dd>This parameter returns the number of dirty cache entries that have
been written to disk. Specifically, the number of pages written to the
wal file in wal mode databases, or the number of pages written to the
database file in rollback mode databases. Any pages written as part of
transaction rollback or database recovery operations are not included.
If an IO or other error occurs while writing a page to disk, the effect
on subsequent SQLITE_DBSTATUS_CACHE_WRITE requests is undefined. The
highwater mark associated with SQLITE_DBSTATUS_CACHE_WRITE is always 0.
</dd></p>
<p><a name="sqlitedbstatuscachespill"></a>
<dt>SQLITE_DBSTATUS_CACHE_SPILL</dt>
<dd>This parameter returns the number of dirty cache entries that have
been written to disk in the middle of a transaction due to the page
cache overflowing. Transactions are more efficient if they are written
to disk all at once. When pages spill mid-transaction, that introduces
additional overhead. This parameter can be used help identify
inefficiencies that can be resolved by increasing the cache size.
</dd></p>
<p><a name="sqlitedbstatusdeferredfks"></a>
<dt>SQLITE_DBSTATUS_DEFERRED_FKS</dt>
<dd>This parameter returns zero for the current value if and only if
all foreign key constraints (deferred or immediate) have been
resolved. The highwater mark is always 0.
</dd>
</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>
|
