123 lines
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123 lines
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<meta name="DC.Title" content="Database file processing: Runtime considerations" />
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<meta name="abstract" content="These topics describe the file processing parameters and other methods or considerations that can affect database file processing." />
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<meta name="DC.subject" content="runtime, considerations, Override with Database File (OVRDBF) command, OVRDBF (Override with Database File) command, command, CL, OVRDBF (Override with Database File), Override with Database File (OVRDBF)" />
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<title>Database file processing: Runtime considerations</title>
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</head>
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<body id="rbafopreopn"><a name="rbafopreopn"><!-- --></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">Database file processing: Runtime considerations</h1>
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<div><p>These topics describe the file processing parameters and other
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methods or considerations that can affect database file processing.</p>
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<p>Before a file is opened for processing, you need to consider how you want
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to use the file in the program or job. A better understanding of the runtime
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file processing parameters can help you avoid unexpected results and improve
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the performance of your program. The parameter values are determined
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by the high-level language program, the file attributes, and any open or override
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commands processed before the high-level language program is called. </p>
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<p>When a file is opened, the attributes in the database file description
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are merged with the parameters in the program. Normally, most of the information
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the system needs for your program to open and process the file is found in
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the file attributes and in the application program itself.</p>
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<p>Sometimes, however, it is necessary to override the processing parameters
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found in the file and in the program. For example, if you want to process
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a member of the file other than the first member, you need to tell the system
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to use the member you want to process. The Override with Database File (OVRDBF)
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command allows you to do this. The OVRDBF command also allows you to specify
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processing parameters that can improve the performance of your job, but that
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cannot be specified in the file attributes or in the program. The OVRDBF command
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parameters take precedence over the file and program attributes. </p>
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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="rbafofileid.htm">File and member name</a></strong><br />
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Before you can process data in a database file, you must identify which file and member you want to use with the FILE and MBR parameters.</li>
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<li class="ulchildlink"><strong><a href="rbafoprocop.htm">File processing options</a></strong><br />
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These topics describe several runtime processing options.</li>
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<li class="ulchildlink"><strong><a href="rbafoprercv.htm">Data recovery and integrity</a></strong><br />
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These topics include the data integrity runtime considerations for more efficient file processing.</li>
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<li class="ulchildlink"><strong><a href="rbafoconcc.htm">Lock shared data</a></strong><br />
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By definition, all database files can be used by many users at the same time. However, some operations can lock the file, member, or data records in a member to prevent them from being shared across jobs.</li>
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<li class="ulchildlink"><strong><a href="rbafosfile.htm">Share database files in the same job or activation group</a></strong><br />
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By default, the database management system lets one file be read and changed by many users at the same time. However, you can share the database files in the same job or activation group through the SHARE parameter.</li>
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<li class="ulchildlink"><strong><a href="rbafoseqop.htm">Sequential-only processing of database files</a></strong><br />
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If your program processes a database file sequentially for input only or output only, you might be able to improve performance using the sequential-only processing (SEQONLY) parameter on the Override with Database File (OVRDBF) or the Open Database File (OPNDBF) command.</li>
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<li class="ulchildlink"><strong><a href="rbafopresum.htm">Summary of runtime considerations for processing database files</a></strong><br />
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This topic shows the parameters that control your program's use of the database file member, where these parameters can be specified.</li>
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<li class="ulchildlink"><strong><a href="rbafostrplpg.htm">Storage pool paging option effect on database performance</a></strong><br />
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The paging option of shared pools can have a significant impact on the performance of reading and changing database files.</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbafoprocess.htm" title="These topics discuss how to make your database files process more efficiently on the i5/OS operating system, how to open, manipulate, and close database files, and how to monitor and manage error messages related to your database files.">Process database files</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="../books/sc415606.pdf" target="_blank">ILE Concepts PDF</a></div>
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<div><a href="../rbam6/rbam6clmain.htm">Control language (CL)</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="../cl/crtpf.htm">Create Physical File (CRTPF) command</a></div>
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<div><a href="../cl/crtlf.htm">Create Logical File (CRTLF) command</a></div>
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<div><a href="../cl/crtsrcpf.htm">Create Source Physical File (CRTSRCPF) command</a></div>
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<div><a href="../cl/addpfm.htm">Add Physical File Member (ADDPFM) command</a></div>
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<div><a href="../cl/addlfm.htm">Add Logical File Member (ADDLFM) command</a></div>
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<div><a href="../cl/chgpf.htm">Change Physical File (CHGPF) command</a></div>
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<div><a href="../cl/chgpfm.htm">Change Physical File Member (CHGPFM) command</a></div>
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<div><a href="../cl/chglf.htm">Change Logical File (CHGLF) command</a></div>
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<div><a href="../cl/chglfm.htm">Change Logical File Member (CHGLFM) command</a></div>
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<div><a href="../cl/chgsrcpf.htm">Change Source Physical File (CHGSRCPF) command</a></div>
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<div><a href="../cl/ovrdbf.htm">Override with Database File (OVRDBF) command</a></div>
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<div><a href="../cl/opndbf.htm">Open Database File (OPNDBF) command</a></div>
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<div><a href="../cl/opnqryf.htm">Open Query File (OPNQRYF) command</a></div>
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<div><a href="../cl/clof.htm">Close File (CLOF) command</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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