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<! "@(#)close.so 10.9 (Sleepycat) 10/10/98">
<!Copyright 1997, 1998 by Sleepycat Software, Inc. All rights reserved.>
<html>
<body bgcolor=white>
<head>
<title>Berkeley DB: DB->close</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btr
ee,hash,hashing,transaction,transactions,locking,logging,access method,access me
thods,java,C,C++">
</head>
<h1>DB->close</h1>
<hr size=1 noshade>
<tt>
<h3>
<pre>
#include <db.h>
<p>
int
DB->close(DB *db, u_int32_t flags);
</pre>
</h3>
<h1>Description</h1>
<p>
The DB->close function flushes any cached database information to disk,
closes any open cursors, frees any allocated resources, and closes any
underlying files.
Since key/data pairs are cached in memory, failing to sync the file with
the DB->close or <a href="../../api_c/Db/sync.html">DB->sync</a> function may result in inconsistent or
lost information.
<p>
The <b>flags</b> parameter must be set to 0 or the following value:
<dl compact>
<a name="DB_NOSYNC">
<p><dt>DB_NOSYNC<dd>Do not flush cached information to disk.
<p>
The DB_NOSYNC flag is a dangerous option.
It should only be set if the application is doing logging (with
transactions) so that the database is recoverable after a system
or application crash, or if the database is always generated from
scratch after any system or application crash.
<p>
<b>It is important to understand that flushing cached information to disk
only minimizes the window of opportunity for corrupted data.</b>
While unlikely, it is possible for database corruption to happen if a
system or application crash occurs while writing data to the database.
To ensure that database corruption never occurs, applications must either:
use transactions and logging with automatic recovery, use logging and
application-specific recovery, or edit a copy of the database,
and, once all applications using the database have successfully called
DB->close, atomically replace the original database with the
updated copy.
</dl>
<p>
When multiple threads are using the Berkeley DB handle concurrently, only a single
thread may call the DB->close function.
<p>
Once DB->close has been called, regardless of its return, the
Berkeley DB handle may not be used again.
<p>
The DB->close
function returns the value of <b>errno</b> on failure, and 0 on success.
<p>
<h1>Errors</h1>
If a fatal error occurs in Berkeley DB, the DB->close function may fail and return
DB_RUNRECOVERY, at which point all subsequent database calls will also
return DB_RUNRECOVERY.
<p>
The DB->close
function may fail and return <b>errno</b>
for any of the errors specified for the following Berkeley DB and C library
functions:
<a href="../../api_c/Db/sync.html">DB->sync</a>,
DBcursor->c_close(3),
dbc->c_am_destroy(3),
<a href="../../api_c/historic/dbm.html">dbm_close</a>,
dbp->am_close(3),
fflush(3),
fprintf(3),
free(3),
<a href="../../api_c/DbLog/db_unregister.html">log_unregister</a>,
<a href="../../api_c/DbMpool/close.html">memp_close</a>,
<a href="../../api_c/DbMpoolFile/close.html">memp_fclose</a>,
<a href="../../api_c/DbMpoolFile/sync.html">memp_fsync</a>,
memset(3),
vfprintf(3),
and
vsnprintf(3).
<p>
<h1>See Also</h1>
<a href="../../api_c/DbEnv/appexit.html">db_appexit</a>,
<a href="../../api_c/DbEnv/appinit.html">db_appinit</a>,
<a href="../../api_c/DbEnv/version.html">db_version</a>,
DB->close,
<a href="../../api_c/Db/cursor.html">DB->cursor</a>,
<a href="../../api_c/Db/del.html">DB->del</a>,
<a href="../../api_c/Db/fd.html">DB->fd</a>,
<a href="../../api_c/Db/get.html">DB->get</a>,
<a href="../../api_c/Db/join.html">DB->join</a>,
<a href="../../api_c/Db/open.html">db_open</a>,
<a href="../../api_c/Db/put.html">DB->put</a>,
<a href="../../api_c/Db/stat.html">DB->stat</a>,
<a href="../../api_c/Db/sync.html">DB->sync</a>,
<a href="../../api_c/Dbc/close.html">DBcursor->c_close</a>,
<a href="../../api_c/Dbc/del.html">DBcursor->c_del</a>,
<a href="../../api_c/Dbc/get.html">DBcursor->c_get</a>
and
<a href="../../api_c/Dbc/put.html">DBcursor->c_put</a>.
</tt>
</body>
</html>
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