84 lines
6.5 KiB
HTML
84 lines
6.5 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="Work with access methods for DDM" />
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<meta name="abstract" content="Access methods control what subsets of functions can be performed after a particular remote file is opened. This might mean that an iSeries program, or a group of programs sharing a non-iSeries file, cannot do all the same operations that are possible using a file that is on the local iSeries server." />
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<meta name="description" content="Access methods control what subsets of functions can be performed after a particular remote file is opened. This might mean that an iSeries program, or a group of programs sharing a non-iSeries file, cannot do all the same operations that are possible using a file that is on the local iSeries server." />
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<meta name="DC.subject" content="access method, remote system, file processing differences, differences, remote file processing, relative record number" />
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<meta name="keywords" content="access method, remote system, file processing differences, differences, remote file processing, relative record number" />
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<meta name="DC.Relation" scheme="URI" content="rbae5ddmop.htm" />
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<meta name="DC.Relation" scheme="URI" content="rbae5accessintents.htm" />
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<meta name="DC.Relation" scheme="URI" content="rbae5keyfield.htm" />
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<meta name="DC.Relation" scheme="URI" content="rbae5delrecords.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1999, 2006" />
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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>Work with access methods for DDM</title>
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</head>
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<body id="rbae5amc"><a name="rbae5amc"><!-- --></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">Work with access methods for DDM</h1>
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<div><p>Access methods control what subsets of functions can be performed
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after a particular remote file is opened. This might mean that an <span class="keyword">iSeries™</span> program, or a group
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of programs sharing a non-<span class="keyword">iSeries</span> file,
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cannot do all the same operations that are possible using a file that is on
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the local <span class="keyword">iSeries server</span>.</p>
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<p>For example, assume that an <span class="keyword">iSeries</span> application
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program opens a keyed file with SHARE(*YES) and performs keyed I/O operations.
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It then calls another program that does relative record number operations
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using the same open data path (ODP) (because SHARE was specified). <dfn class="term">Relative
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record numbers</dfn> specify the relationship between the location of a record
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and the beginning of a database file, member, or subfile. If the first program
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is redirected by an <span class="cmdname">Override with Database File (OVRDBF) </span>command
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to use a remote keyed file on a <span class="keyword">System/36™</span>,
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this scheme no longer works. If a <em>keyed</em> access method is selected,
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record number operations fail. If a <em>record number</em> access method is
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selected, keyed operations fail.</p>
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<p>Notice that when both source and target servers are <span class="keyword">iSeries server</span>s,
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access methods are not used. A potential problem exists when the target server
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is neither an <span class="keyword">iSeries server</span> nor
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a <span class="keyword">System/38™</span>. Notice also that
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the combined-access access method (*COMBINED) is not supported by <span class="keyword">System/36</span>, and probably not by any target
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other than an <span class="keyword">iSeries server</span> or <span class="keyword">System/38</span>.</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="rbae5accessintents.htm">Access intents</a></strong><br />
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When a program opens a file, it must specify how it intends to work with the records in the file: read, add, update, delete, or a combination of these.</li>
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<li class="ulchildlink"><strong><a href="rbae5keyfield.htm">Key field updates</a></strong><br />
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An <span class="keyword">iSeries</span> program
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is allowed to change any part of a data record including key fields. </li>
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<li class="ulchildlink"><strong><a href="rbae5delrecords.htm">Deleted records</a></strong><br />
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On the <span class="keyword">iSeries server</span>,
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a record is marked as deleted by the server.</li>
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<li class="ulchildlink"><strong><a href="rbae5brp.htm">Blocked record processing</a></strong><br />
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If SEQONLY is used to block records sent to a remote server, the records are not sent until the block is full. If a source job is canceled before a block is sent, the records in the block are lost. If blocking is used, the user should make sure a force end of data or close of the file is done before canceling the source job.</li>
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<li class="ulchildlink"><strong><a href="rbae5varlength.htm">Variable-length records</a></strong><br />
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If your <span class="keyword">iSeries</span> source
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server is running OS/400<sup>®</sup> Version 2 Release 1 Modification 1, DDM supports
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variable-length record files as defined in the DDM architecture.</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="rbae5ddmop.htm" title="This topic provides task-oriented information and examples that describe various aspects of DDM operation considerations.">Operating considerations for DDM</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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