62 lines
4.2 KiB
HTML
62 lines
4.2 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 name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Performance considerations" />
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<meta name="abstract" content="This topic includes tips for the best performance of join logical files." />
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<meta name="description" content="This topic includes tips for the best performance of join logical files." />
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<meta name="DC.subject" content="improving, performance, suggestions" />
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<meta name="keywords" content="improving, performance, suggestions" />
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<meta name="DC.Relation" scheme="URI" content="rbafojoincons.htm" />
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<meta name="DC.Relation" scheme="URI" content="rbafoapdyn.htm" />
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<meta name="DC.Relation" scheme="URI" content="rbafoshrap.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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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Performance considerations</title>
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</head>
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<body id="rbafoperfc"><a name="rbafoperfc"><!-- --></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">Performance considerations</h1>
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<div><p>This topic includes tips for the best performance
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of join logical files. </p>
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<div class="p">You can do the following things to improve the performance of join logical
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files: <ul><li>If the physical files you join have a different number of records, specify
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the physical file with fewest records first (first parameter following the
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JOIN keyword).</li>
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<li>Consider using the DYNSLT keyword. </li>
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<li>Consider describing your join logical file so it can automatically share
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an existing access path. <div class="note"><span class="notetitle">Note:</span> Join logical files always have access paths
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using the second field of the pair of fields specified in the JFLD keyword.
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This field acts like a key field in simple logical files. If an access path
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does not already exist, the access path is implicitly created with immediate
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maintenance.</div>
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</li>
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</ul>
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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="rbafojoincons.htm" title="These topics include the performance and integrity considerations for join logical files. They also provide a summary of rules for join logical files.">Join logical file considerations</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rbafoapdyn.htm" title="With the dynamic select/omit operation, when a program reads records from the file, the system only returns those records that meet the select/omit values. That is, the actual select/omit processing is done when records are read by a program, rather than when the records are added or changed.">Dynamic select/omit</a></div>
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<div><a href="rbafoshrap.htm" title="When two or more files are based on the same physical files and the same key fields in the same order, they automatically share the same keyed sequence access path. When access paths are shared, the amount of system activity required to maintain access paths and the amount of auxiliary storage used by the files is reduced.">Use existing access paths</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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