69 lines
4.5 KiB
HTML
69 lines
4.5 KiB
HTML
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<meta name="DC.Title" content="Determining unnecessary MQTs" />
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<meta name="abstract" content="You can easily determine which MQTs are being used for query optimization. However, you can now easily find all MQTs and retrieve statistics on MQT usage as a result of iSeries Navigator and i5/OS functionality." />
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<title>Determining unnecessary MQTs</title>
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<body id="rzajqmqtunnecessary"><a name="rzajqmqtunnecessary"><!-- --></a>
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<img src="./delta.gif" alt="Start of change" /><!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Determining unnecessary MQTs</h1>
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<div><p>You can easily determine which MQTs are being used for query optimization.
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However, you can now easily find all MQTs and retrieve statistics on MQT
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usage as a result of iSeries™ Navigator and i5/OS™ functionality.</p>
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<div class="section"><p>To assist you in tuning your performance, this function now produces
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statistics on MQT usage in a query. To access this through the iSeries Navigator,
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navigate to: <span class="menucascade"><span class="uicontrol">Database</span> > <span class="uicontrol">Schemas</span> > <span class="uicontrol">Tables</span></span>. Right-click your table and select <span class="uicontrol">Show
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Materialized Query Tables</span>.</p>
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<div class="note"><span class="notetitle">Note:</span> You can also view the statistics
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through an application programming interface (API).</div>
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<p> In addition
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to all existing attributes of an MQT, two new fields have been added to the iSeries Navigator.</p>
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<p>These
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new fields are:</p>
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<dl><dt class="dlterm">Last Query Use</dt>
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<dd>States the timestamp when the MQT was last used by the optimizer to replace
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user specified tables in a query.</dd>
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<dt class="dlterm">Query Use Count</dt>
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<dd>Lists the number of instances the MQT was used by the optimizer to replace
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user specified tables in a query.</dd>
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</dl>
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</div>
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<div class="section"> <p>The fields start and stop counting based on your situation,
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or the actions you are currently performing on your system. A save and restore
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procedure does not reset the statistics counter if the MQT is restored over
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an existing MQT. If an MQT is restored that does not exist on the server,
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the statistics are reset.</p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzajqmqt.htm" title="Materialized query tables (MQTs) (also referred to as automatic summary tables or materialized views) can provide performance enhancements for queries.">Materialized query table optimization</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../apis/qusrmbrd.htm">Retrieve member description (QUSRMBRD) command</a></div>
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</div>
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</div>
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<img src="./deltaend.gif" alt="End of change" /></body>
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