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<h1><a name="kanchor122"></a>Persistent and transient fields</h1>
<p>Do not create fields that you don't need for persistence</p><a name="Advantage"></a>
<h2>Advantage</h2>
<p>Storing only needed information will help to keep your database footprint as small as possible.</p><a name="Effect"></a>
<h2>Effect</h2>
<p>If your persistent class contains fields that do not need to be stored you should mark them as transient to prevent them from being stored:</p>
<p MadCap:conditions="Global.Primary:java" />
<p MadCap:conditions="Primary..NET">
<p>.NET: <code>public class NotStorable { [Transient] private int length; . . . }</code></p>
</p>
<p MadCap:conditions="Global.Primary:net" />
<p>You can use <a href="../../advanced_topics/callbacks.htm">Callbacks</a> or <a href="../../advanced_topics/type_handling/translators.htm">Translators</a> to set transient fields on retrieval.</p>
<p>Also avoid storing classes having only transient information - their indexes' maintenance will produce unnecessary performance overhead.</p>
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