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<title>Berkeley DB Reference Guide: Page fill factor</title>
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<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></h3></td>
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<h1 align=center>Page fill factor</h1>
<p>The density, or page fill factor, is an approximation of the number of
keys allowed to accumulate in any one bucket, determining when the hash
table grows or shrinks. If you know the average sizes of the keys and
data in your dataset, setting the fill factor can enhance performance.
A reasonable rule to use to compute fill factor is:
<p><blockquote><pre>(pagesize - 32) / (average_key_size + average_data_size + 8)</pre></blockquote>
<p>The desired density within the hash table can be specified by calling
the <a href="../../api_c/db_set_h_ffactor.html">DB->set_h_ffactor</a> function. If no density is specified, one will
be selected dynamically as pages are filled.
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