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13<b>DbEnv::log_printf</b>
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21<b><pre>
22#include &lt;db_cxx.h&gt;
23<p>
24int
25DbEnv::log_printf(DB_TXN *txnid, const char *fmt, ...);
26</pre></b>
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28<b>Description: DbEnv::log_printf</b>
29<p>The DbEnv::log_printf method appends an informational message to the Berkeley DB
30database environment log files.</p>
31<p>The DbEnv::log_printf method allows applications to include information in
32the database environment log files, for later review using the
33<a href="../utility/db_printlog.html">db_printlog</a> utility.  This method is intended for debugging and
34performance tuning.</p>
35<p>The DbEnv::log_printf method
36either returns a non-zero error value
37or throws an exception that encapsulates a non-zero error value on
38failure, and returns 0 on success.
39</p>
40<b>Parameters</b> <br>
41 <b>txnid</b><ul compact><li>If the logged message refers to an application-specified transaction,
42the <b>txnid</b> parameter is a transaction handle returned from
43<a href="../api_cxx/txn_begin.html">DbEnv::txn_begin</a>; otherwise NULL.</ul>
44 <b>fmt</b><ul compact><li>A format string that specifies how subsequent arguments (or arguments
45accessed via the variable-length argument facilities of stdarg(3)) are
46converted for output.  The format string may contain any formatting
47directives supported by the underlying C library vsnprintf(3)
48function.</ul>
49<br>
50<br><b>Errors</b>
51<p>The DbEnv::log_printf method
52may fail and throw
53<a href="../api_cxx/except_class.html">DbException</a>,
54encapsulating one of the following non-zero errors, or return one of
55the following non-zero errors:</p>
56<br>
57<b>EINVAL</b><ul compact><li>An
58invalid flag value or parameter was specified.</ul>
59<br>
60<hr size=1 noshade>
61<br><b>Class</b>
62<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/logc_class.html">DbLogc</a>, <a href="../api_cxx/lsn_class.html">DbLsn</a>
63<br><b>See Also</b>
64<a href="../api_cxx/log_list.html">Logging Subsystem and Related Methods</a>
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