48 lines
3.1 KiB
HTML
48 lines
3.1 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta name="Robots" content="index,follow" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="CQE query optimization considerations" />
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<meta name="abstract" content="The Classic Query Engine (CQE) optimizer optimizes the query using the first partition member in the partitioned table. This access method is used to access rows from all of the partitions." />
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<meta name="description" content="The Classic Query Engine (CQE) optimizer optimizes the query using the first partition member in the partitioned table. This access method is used to access rows from all of the partitions." />
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<meta name="DC.Relation" scheme="URI" content="cqe.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="cqeoptimize" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>CQE query optimization considerations</title>
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</head>
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<body id="cqeoptimize"><a name="cqeoptimize"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">CQE query optimization considerations</h1>
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<div><p>The Classic Query Engine (CQE) optimizer optimizes
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the query using the first partition member in the partitioned table. This
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access method is used to access rows from all of the partitions.</p>
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<p>DB2<sup>®</sup> UDB
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Symmetric Multiprocessing feature data access methods cannot be used to access
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a partitioned table, but they can be used when processing temporary tables
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and for creating temporary indexes.</p>
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<p>If the partitioned table is used in a query containing a subquery, the
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optimizer does not attempt to implement the query as a join composite query.
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This keeps the partitioned table from being materialized because of the join.</p>
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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="cqe.htm" title="When queries are implemented using Classic Query Engine (CQE), you need to be aware of how the query is optimized including materialization and index usage.">Queries using Classic Query Engine</a></div>
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</div>
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</div>
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</body>
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</html>
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