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<h2 class="title" style="clear: both"><a id="configcache"></a>Configuring the In-Memory Cache</h2>
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<p>
SQLite provides an in-memory cache which you
size according to the maximum number of database pages that
you want to hold in memory at any given time.
</p>
<p>
Berkeley DB also provides an in-memory cache that performs the
same function as SQLite. You can configure this
cache using the exact same PRAGMAs as you are used to
using with SQLite. See
<a class="ulink" href="http://www.sqlite.org/pragma.html#pragma_cache_size" target="_top">PRAGMA cache_size</a>
and
<a class="ulink" href="http://www.sqlite.org/pragma.html#pragma_default_cache_size" target="_top">PRAGMA default_cache_size</a>
for details. As is the case with SQLite, you use these
PRAGMAs to describe the total number of pages that you
want in the cache.
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Note that you can change the cache size only if no table
operations have been executed on the database. In other
words, to change your cache size:
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<p>
Open a handle to your database.
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Execute <code class="literal">PRAGMA cache_size</code>
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<p>
Proceed with any table modification operations
(<code class="literal">CREATE</code>, <code class="literal">UPDATE</code>, <code class="literal">INSERT</code>,
<code class="literal">SELECT</code>) that you might want to
perform.
</p>
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<p>
Alternatively, you can set you cache size with your
<code class="literal">DB_CONFIG</code> file, and so skip the
necessity of executing the PRAGMA. See the <a class="ulink" href="http://download.oracle.com/docs/cd/E17076_02/html/api_reference/C/BDB-C_APIReference.pdf" target="_top">Berkeley DB C API
</a>
for details.
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