101 lines
7.9 KiB
HTML
101 lines
7.9 KiB
HTML
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<title>Performance and query optimization</title>
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</head>
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<body id="rzajqkickoff"><a name="rzajqkickoff"><!-- --></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 and query optimization</h1>
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<div><p>The goal of database performance tuning is to minimize the response
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time of your queries and to make the best use of your server's resources by
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minimizing network traffic, disk I/O, and CPU time. This goal can only be
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achieved by understanding the logical and physical structure of your data,
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understanding the applications used on your server, and understanding how
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the many conflicting uses of your database may impact database performance.</p>
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<p>The best way to avoid performance problems is to ensure that performance
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issues are part of your ongoing development activities. Many of the most significant
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performance improvements are realized through careful design at the beginning
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of the database development cycle. To most effectively optimize performance,
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you must identify the areas that will yield the largest performance increases
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over the widest variety of situations and focus your analysis on those areas. </p>
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<p>Many of the examples within this publication illustrate a query written
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through either an SQL or an OPNQRYF query interface. The interface chosen
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for a particular example does not indicate an operation exclusive to that
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query interface, unless explicitly noted. It is only an illustration of one
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possible query interface. Most examples can be easily rewritten into whatever
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query interface that you prefer.</p>
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<div class="note"><span class="notetitle">Note:</span> Read the <a href="codedisclaimer.htm">Code license and disclaimer information</a> for important legal
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information.</div>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="whatsnew.htm">What's new for V5R4</a></strong><br />
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The following information was added or updated in this release of the information:</li>
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<li class="ulchildlink"><strong><a href="rzajqprint.htm">Printable PDF</a></strong><br />
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Use this to view and print a PDF of this information.</li>
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<li class="ulchildlink"><strong><a href="queryoptimize.htm">Query Engine Overview</a></strong><br />
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DB2<sup>®</sup> UDB
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for iSeries™ provides
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two query engines to process queries: the Classic Query Engine (CQE) and the
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SQL Query Engine (SQE). </li>
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<li class="ulchildlink"><strong><a href="rzajqdta.htm">Data access on DB2 UDB for iSeries: data access paths and methods</a></strong><br />
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Data access methods are used to process queries and access data.</li>
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<li class="ulchildlink"><strong><a href="per0001.htm">Processing queries: Overview</a></strong><br />
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This overview of the query optimizer provides guidelines for designing queries that will perform and will use server resources more efficiently.</li>
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<li class="ulchildlink"><strong><a href="queryopt.htm">Optimizing query performance using query optimization tools</a></strong><br />
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Query optimization is an iterative process. You can gather performance information about your queries and control the processing of your queries.</li>
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<li class="ulchildlink"><strong><a href="efindex.htm">Creating an index strategy</a></strong><br />
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<span class="keyword">DB2 Universal Database™ for iSeries™</span> provides
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two basic means for accessing tables: a table scan and an index-based retrieval.
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Index-based retrieval is typically more efficient than table scan when less
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than 20% of the table rows are selected.</li>
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<li class="ulchildlink"><strong><a href="opens.htm">Application design tips for database performance</a></strong><br />
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There are some design tips that you can apply when designing SQL applications to maximize your database performance.</li>
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<li class="ulchildlink"><strong><a href="progtech.htm">Programming techniques for database performance</a></strong><br />
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By changing the coding of your queries, you can improve their performance.</li>
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<li class="ulchildlink"><strong><a href="genconsid.htm">General DB2 UDB for iSeries performance considerations</a></strong><br />
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As you code your applications, there are some general tips that can help you optimize performance.</li>
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<li class="ulchildlink"><strong><a href="rzajqdmd.htm">Database monitor: Formats</a></strong><br />
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This section contains the formats used to create the database monitor SQL tables and views.</li>
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<li class="ulchildlink"><strong><a href="rzajqmrdm.htm">Memory Resident Database Monitor: DDS</a></strong><br />
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The following DDS statements are used to create the memory resident database monitor physical and logical files.</li>
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<li class="ulchildlink"><strong><a href="rzajqmsgref.htm">Query optimizer messages reference</a></strong><br />
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See the following for query optimizer message reference:</li>
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</ul>
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</div>
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</body>
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