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<title>Berkeley DB Reference Guide: Configuring logging</title>
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<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Logging Subsystem</dl></h3></td>
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<h3 align=center>Configuring logging</h3>
<p>The aspects of logging that may be configured are the size of the
logging subsystem's region, the size of the log files on disk and the
size of the log buffer in memory.  The <a href="../../api_c/env_set_lg_regionmax.html">DB_ENV-&gt;set_lg_regionmax</a> method
specifies the size of the logging subsystem's region, in bytes.  The
logging subsystem's default size is 60KB.  This value may need to be
increased if a large number of files are registered with the Berkeley DB log
manager, for example, by opening a large number of Berkeley DB database files
in a transactional application.</p>
<p>The <a href="../../api_c/env_set_lg_max.html">DB_ENV-&gt;set_lg_max</a> method specifies the individual log file size for
all the applications sharing the Berkeley DB environment.  Setting the log
file size is largely a matter of convenience and a reflection of the
application's preferences in backup media and frequency.  However,
setting the log file size too low can potentially cause problems because
it would be possible to run out of log sequence numbers, which requires
a full archival and application restart to reset.  See
<a href="../../ref/log/limits.html">Log file limits</a> for more
information.</p>
<p>The <a href="../../api_c/env_set_lg_bsize.html">DB_ENV-&gt;set_lg_bsize</a> method specifies the size of the in-memory log
buffer, in bytes.  Log information is stored in memory until the buffer
fills up or transaction commit forces the buffer to be written to disk.
Larger buffer sizes can significantly increase throughput in the
presence of long-running transactions, highly concurrent applications,
or transactions producing large amounts of data.  By default, the buffer
is 32KB.</p>
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