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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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<h1 align=center>Configuring logging</h1>
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<p>The aspects of logging that may be configured are the size of the
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logging subsystem's region, the size of the log files on disk and the
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size of the log buffer in memory. The <a href="../../api_c/env_set_lg_regionmax.html">DB_ENV->set_lg_regionmax</a>
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interface specifies the size of the logging subsystem's region, in
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bytes. The logging subsystem's default size is 60KB. This value may
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need to be increased if a large number of files are registered with the
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Berkeley DB log manager, for example, by opening a large number of Berkeley DB
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database files in a transactional application.
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<p>The <a href="../../api_c/env_set_lg_max.html">DB_ENV->set_lg_max</a> interface specifies the individual log file
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size for all the applications sharing the Berkeley DB environment. Setting
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the log file size is largely a matter of convenience and a reflection
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of the application's preferences in backup media and frequency.
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However, setting the log file size too low can potentially cause
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problems because it would be possible to run out of log sequence
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numbers, which requires a full archival and application restart to
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reset. See <a href="../../ref/log/limits.html">Log file limits</a> for more
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<p>The <a href="../../api_c/env_set_lg_bsize.html">DB_ENV->set_lg_bsize</a> interface specifies the size of the
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in-memory log buffer, in bytes. Log information is stored in memory
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until the buffer fills up or transaction commit forces the buffer to be
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written to disk. Larger buffer sizes can significantly increase
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throughput in the presence of long-running transactions, highly
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concurrent applications, or transactions producing large amounts of
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data. By default, the buffer is 32KB.
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