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<! "@(#)checkpoint.so 10.8 (Sleepycat) 9/29/98">
<!Copyright 1997, 1998 by Sleepycat Software, Inc. All rights reserved.>
<html>
<body bgcolor=white>
<head>
<title>Berkeley DB: DbTxnMgr::checkpoint</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>DbTxnMgr::checkpoint</h1>
<hr size=1 noshade>
<tt>
<h3>
<pre>
#include <db_cxx.h>
<p>
int
DbTxnMgr::checkpoint(u_int32_t kbyte, u_int32_t min) const;
</pre>
</h3>
<h1>Description</h1>
<p>
The DbTxnMgr::checkpoint method flushes the underlying memory pool,
writes a checkpoint record to the log and then flushes the log.
<p>
If either <b>kbyte</b> or <b>min</b> is non-zero, the checkpoint is only
done if more than <b>min</b> minutes have passed since the last checkpoint,
or if more than <b>kbyte</b> kilobytes of log data have been written since
the last checkpoint.
<p>
The DbTxnMgr::checkpoint
method either returns <b>errno</b> or throws an exception that
encapsulates an <b>errno</b> on failure, and 0 on success,
and DB_INCOMPLETE if there were pages that
needed to be written but that <a href="../../api_cxx/DbMpool/sync.html">DbMpool::sync</a> was unable to write
immediately.
In this case, the DbTxnMgr::checkpoint call should be retried.
<p>
The DbTxnMgr::checkpoint method is the underlying method used by the <a href="../../utility/db_checkpoint.html">db_checkpoint</a> utility.
See the <a href="../../utility/db_checkpoint.html">db_checkpoint</a> utility source code for an example of using DbTxnMgr::checkpoint
in a POSIX 1003.1 environment.
<p>
<h1>Errors</h1>
If a fatal error occurs in Berkeley DB, the DbTxnMgr::checkpoint method may fail and either
return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY,
at which point all subsequent database calls will also fail in the same
way. Methods marked as returning <b>errno</b> will, by default, throw
an exception that encapsulates the error information. The default error
behavior can be changed, see <a href="../../api_cxx/DbException/class.html">DbException</a>.
<p>
The DbTxnMgr::checkpoint
method may fail and throw an exception
for any of the errors specified for the following Berkeley DB and C library
functions:
abort(3),
fcntl(3),
fflush(3),
fprintf(3),
free(3),
getpid(3),
<a href="../../api_cxx/DbLog/compare.html">DbLog::compare</a>,
<a href="../../api_cxx/DbLog/put.html">DbLog::put</a>,
malloc(3),
memcpy(3),
<a href="../../api_cxx/DbMpool/sync.html">DbMpool::sync</a>,
memset(3),
strerror(3),
time(3),
vfprintf(3),
and
vsnprintf(3).
<p>
In addition, the DbTxnMgr::checkpoint
method may fail and throw an exception
or return <b>errno</b>
for the following conditions:
<p>
<dl compact>
<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
<p>
</dl>
<p>
<h1>Class</h1>
<a href="../../api_cxx/DbTxnMgr/class.html">DbTxnMgr</a>
<p>
<h1>See Also</h1>
<a href="../../api_cxx/DbTxnMgr/begin.html">DbTxnMgr::begin</a>,
DbTxnMgr::checkpoint,
<a href="../../api_cxx/DbTxnMgr/close.html">DbTxnMgr::close</a>,
<a href="../../api_cxx/DbTxnMgr/open.html">DbTxnMgr::open</a>,
<a href="../../api_cxx/DbTxnMgr/stat.html">DbTxnMgr::stat</a>
and
<a href="../../api_cxx/DbTxnMgr/unlink.html">DbTxnMgr::unlink</a>.
</tt>
</body>
</html>
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