64 lines
4.4 KiB
HTML
64 lines
4.4 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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<meta name="DC.Title" content="Improve SQL blocking performance when using FETCH FOR n ROWS" />
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<meta name="abstract" content="Special performance considerations should be made for the following points when using FETCH FOR n ROWS." />
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<meta name="description" content="Special performance considerations should be made for the following points when using FETCH FOR n ROWS." />
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<meta name="DC.subject" content="improving performance, SQL blocking, performance improvement, blocking, SQL, command (CL), Override Database File (OVRDBF), OVRDBF (Override Database File), Override Database File (OVRDBF) command" />
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<meta name="keywords" content="improving performance, SQL blocking, performance improvement, blocking, SQL, command (CL), Override Database File (OVRDBF), OVRDBF (Override Database File), Override Database File (OVRDBF) command" />
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<meta name="DC.Relation" scheme="URI" content="fetchnrows.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<title>Improve SQL blocking performance when using FETCH FOR n ROWS</title>
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</head>
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<body id="improvesqlblock"><a name="improvesqlblock"><!-- --></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">Improve SQL blocking performance when using FETCH FOR n ROWS</h1>
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<div><p>Special performance considerations should be made for the following
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points when using FETCH FOR n ROWS.</p>
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<div class="section"><div class="p">You can improve SQL blocking performance with the following: <ul><li>The attribute information in the host structure array or the descriptor
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associated with the row storage area should match the attributes of the columns
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retrieved.</li>
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<li>The application should retrieve as many rows as possible with a single
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multiple-row FETCH call. The blocking factor for a multiple-row FETCH request
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is not controlled by the system page sizes or the SEQONLY parameter on the
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OVRDBF command. It is controlled by the number of rows that are requested
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on the multiple-row FETCH request.</li>
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<li>Single- and multiple-row FETCH requests against the same cursor should
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not be mixed within a program. If one FETCH against a cursor is treated as
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a multiple-row FETCH, all fetches against that cursor are treated as multiple-row
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fetches. In that case, each of the single-row FETCH requests is treated as
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a multiple-row FETCH of one row.</li>
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<li>The PRIOR, CURRENT, and RELATIVE scroll options should not be used with
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multiple-row FETCH statements. To allow random movement of the cursor by
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the application, the database manager must maintain the same cursor position
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as the application. Therefore, the SQL run-time treats all FETCH requests
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against a scrollable cursor with these options specified as multiple-row FETCH
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requests.</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>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="fetchnrows.htm" title="Applications that perform many FETCH statements in succession may be improved by using FETCH FOR n ROWS. With this clause, you can retrieve multiple rows of data from a table and put them into a host structure array or row storage area with a single FETCH.">Use FETCH FOR n ROWS</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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