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<h1 class="topictitle1">Think about index order</h1>


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<p><span>Derby</span> allows you to create index columns in descending order in addition
to creating them in ascending order, the default. Descending indexes provide
performance benefits for the following kinds of queries that require sorting data in descending order.</p>

<p>To ensure performance benefits, verify that the descending index is being
used. See <a href="ttundepth33391.html#ttundepth33391">Analyzing statement execution</a> for
information on how to do this. </p>

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<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="ctundepth23033.html" title="">Always create indexes</a></div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
<div><a href="ctundepth1002853.html" title="Indexes are useful when a query contains a WHERE clause.">Create useful indexes</a></div>
<div><a href="ctundepth1003116.html" title="">Make sure indexes are being used, and rebuild them</a></div>
<div><a href="ctundepth1003369.html" title="">Think about join order</a></div>
<div><a href="ctundepth1003672.html" title="">Decide whether a descending index would be useful</a></div>
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