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<a href="../c3ref/intro.html"><h2>SQLite C Interface</h2></a>
<h2>Database Snapshot</h2>
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<blockquote><pre>
typedef struct sqlite3_snapshot {
unsigned char hidden[48];
} sqlite3_snapshot;
</pre></blockquote>
<p>
An instance of the snapshot object records the state of a <a href="../wal.html">WAL mode</a>
database for some specific point in history.</p>
<p>In <a href="../wal.html">WAL mode</a>, multiple <a href="../c3ref/sqlite3.html">database connections</a> that are open on the
same database file can each be reading a different historical version
of the database file. When a <a href="../c3ref/sqlite3.html">database connection</a> begins a read
transaction, that connection sees an unchanging copy of the database
as it existed for the point in time when the transaction first started.
Subsequent changes to the database from other connections are not seen
by the reader until a new read transaction is started.</p>
<p>The sqlite3_snapshot object records state information about an historical
version of the database file so that it is possible to later open a new read
transaction that sees that historical version of the database rather than
the most recent version.
</p><p>1 Constructor using this object: <a href="../c3ref/snapshot_get.html">sqlite3_snapshot_get()</a></p>
<p>1 Destructor using this object: <a href="../c3ref/snapshot_free.html">sqlite3_snapshot_free()</a></p>
<p>3 Methods using this object:
<a href="../c3ref/snapshot_cmp.html">sqlite3_snapshot_cmp()</a>,
<a href="../c3ref/snapshot_open.html">sqlite3_snapshot_open()</a>,
<a href="../c3ref/snapshot_recover.html">sqlite3_snapshot_recover()</a></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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