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<a href="intro.html"><h2>SQLite C Interface</h2></a>
<h2>Record A Database Snapshot</h2>
</div>
<blockquote><pre>
int sqlite3_snapshot_get(
sqlite3 *db,
const char *zSchema,
sqlite3_snapshot **ppSnapshot
);
</pre></blockquote>
<p>
The <a href="../c3ref/snapshot_get.html">sqlite3_snapshot_get(D,S,P)</a> interface attempts to make a
new <a href="../c3ref/snapshot.html">sqlite3_snapshot</a> object that records the current state of
schema S in database connection D. On success, the
<a href="../c3ref/snapshot_get.html">sqlite3_snapshot_get(D,S,P)</a> interface writes a pointer to the newly
created <a href="../c3ref/snapshot.html">sqlite3_snapshot</a> object into *P and returns SQLITE_OK.
If there is not already a read-transaction open on schema S when
this function is called, one is opened automatically.</p>
<p>The following must be true for this function to succeed. If any of
the following statements are false when sqlite3_snapshot_get() is
called, SQLITE_ERROR is returned. The final value of *P is undefined
in this case.</p>
<p><ul>
<li> The database handle must not be in <a href="../c3ref/get_autocommit.html">autocommit mode</a>.</p>
<p><li> Schema S of <a href="../c3ref/sqlite3.html">database connection</a> D must be a <a href="../wal.html">WAL mode</a> database.</p>
<p><li> There must not be a write transaction open on schema S of database
connection D.</p>
<p><li> One or more transactions must have been written to the current wal
file since it was created on disk (by any connection). This means
that a snapshot cannot be taken on a wal mode database with no wal
file immediately after it is first opened. At least one transaction
must be written to it first.
</ul></p>
<p>This function may also return SQLITE_NOMEM. If it is called with the
database handle in autocommit mode but fails for some other reason,
whether or not a read transaction is opened on schema S is undefined.</p>
<p>The <a href="../c3ref/snapshot.html">sqlite3_snapshot</a> object returned from a successful call to
<a href="../c3ref/snapshot_get.html">sqlite3_snapshot_get()</a> must be freed using <a href="../c3ref/snapshot_free.html">sqlite3_snapshot_free()</a>
to avoid a memory leak.</p>
<p>The <a href="../c3ref/snapshot_get.html">sqlite3_snapshot_get()</a> interface is only available when the
<a href="../compile.html#enable_snapshot">SQLITE_ENABLE_SNAPSHOT</a> compile-time option is used.
</p><p>See also lists of
<a href="objlist.html">Objects</a>,
<a href="constlist.html">Constants</a>, and
<a href="funclist.html">Functions</a>.</p>
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