2011-09-13 17:44:24 +00:00
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Heap access method specific configuration</title>
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<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
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<link rel="up" href="am_conf.html" title="Chapter 2. Access Method Configuration" />
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<link rel="prev" href="hash_conf.html" title="Hash access method specific configuration" />
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<link rel="next" href="rq_conf.html" title="Queue and Recno access method specific configuration" />
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<div class="libver">
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2012-11-14 21:35:20 +00:00
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<p>Library Version 11.2.5.3</p>
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2011-09-13 17:44:24 +00:00
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Heap access method specific configuration</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="hash_conf.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 2.
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Access Method Configuration
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="rq_conf.html">Next</a></td>
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</tr>
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</table>
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="heap_conf"></a>Heap access method specific configuration</h2>
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</div>
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</div>
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</div>
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<p>
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Configuring the Heap access method is fairly simple. Beyond the general
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2012-11-14 21:35:20 +00:00
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configuration required for any access method, you can configure how large
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the database will become, as well as the amount by which the database grows.
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2011-09-13 17:44:24 +00:00
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</p>
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<p>
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If you provide no configuration relative to the heap size, then the
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database will grow without bound. Whether this is desirable depends on
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how much disk space is available to your application.
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</p>
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<p>
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You can limit the size of the on-disk database file by using the
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<a href="../api_reference/C/dbset_heapsize.html" class="olink">DB->set_heapsize()</a> method. If the size specified on this method is
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reached, then further attempts to insert/update records will fail
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with a <code class="literal">DB_HEAP_FULL</code> error message.
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2012-11-14 21:35:20 +00:00
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</p>
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<p>
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Heap databases are organized into regions, and each region is a constant
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size. The size of the region in a heap database is limited by the page
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size, the first page of the region contains a bitmap describing the
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available space on the remaining pages in the region. When the database
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experiences write contention, a region is added to reduce contention.
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This means heap databases can grow in size very quickly. In order to
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control the amount by which the database increases, the size of the region
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is configurable via <a href="../api_reference/C/dbset_heap_regionsize.html" class="olink">DB->set_heap_regionsize()</a>.
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2011-09-13 17:44:24 +00:00
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</p>
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<td width="40%" align="left"><a accesskey="p" href="hash_conf.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="am_conf.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="rq_conf.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Hash access method specific configuration </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Queue and Recno access method specific configuration</td>
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</tr>
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</table>
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