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<h1>Defragment</h1>
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<p>.NET: <code>Defragment.Defrag("sample.db4o")</code></p>
</p>
<p MadCap:conditions="Global.Primary:net" /><a name="Advantage"></a>
<h2>Advantage</h2>
<p>It is recommended to run Defragment frequently to reduce the database file size and to remove unused fields and freespace slots.</p><a name="Effect"></a>
<h2>Effect</h2>
<p>db4o does not discard fields from the database file that are no longer being used. Within the database file quite a lot of space is used for transactional processing. Objects are always written to a new slot when they are modified. Deleted objects continue to occupy 8 bytes until the next Defragment run. Defragment cleans all this up by writing all objects to a completely new database file. The resulting file will be smaller and faster.</p><a name="Alternate Strategies"></a>
<h2>Alternate Strategies</h2>
<p>Instead of deleting objects it can be an option to mark objects as deleted with a "deleted" boolean field and to clean them out (by not copying them to the new database file) during the Defragment run. Two advantages: </p>
<ol>
<li value="1">Deleted objects can be restored. </li>
<li value="2">In case there are multiple references to a deleted object, none of them would point to null. </li>
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