91 lines
5.2 KiB
HTML
91 lines
5.2 KiB
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<title>Asynchronous job usage (ASYNCJ) parameter with DB2 Multisystem</title>
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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">Asynchronous job usage (ASYNCJ) parameter with DB2<sup>®</sup> Multisystem</h1>
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<div><p>You can use the ASYNCJ parameter to control the usage of the temporary
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result writer.</p>
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<div class="section"><p>The ASYNCJ parameter has the following options:</p>
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<ul><li>*ANY—allows the temporary result writer jobs to be used for database queries
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involving distributed files.</li>
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<li>*DIST—allows the temporary result writer jobs to be used for database
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queries involving distributed files.</li>
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<li>*LOCAL—allows the temporary result writer jobs to be used for queries
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of local files only. Although this option is allowed, currently there is no
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system support for using temporary result writers for local query processing.
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*LOCAL was added to disable the temporary result writer for distributed queries,
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yet still allow communications to be performed asynchronously.</li>
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<li>*NONE—never use the temporary result writer. In addition, when distributed
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processing is performed, communications are performed synchronously. This
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can be very useful when analyzing queries, because it allows query debug messages
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from remote systems to be returned to the local system.</li>
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</ul>
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<div class="p">The following example shows you how to disable asynchronous job usage
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for distributed file processing: <pre>CHGQRYA ASYNCJ(*LOCAL)</pre>
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</div>
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<p>This
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command prevents asynchronous jobs from being used for queries involving distributed
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files.</p>
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<div class="p">The following example shows you how to completely disable asynchronous
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job usage: <pre>CHGQRYA ASYNCJ(*NONE)</pre>
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</div>
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<p>This
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command prevents asynchronous jobs from being used for any queries. In addition,
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for queries involving distributed files, communications to remote systems
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are done in a synchronous fashion.</p>
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<div class="p">The following example shows you how
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to use the CHGQRYA command in combination with the Start Debug (STRDBG) command
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to analyze a distributed query: <pre>STRDBG UPDPROD(*YES)
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CHGQRYA ASYNCJ(*NONE)
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STRSQL
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SELECT COUNT(*) FROM EMPLOYEE A</pre>
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</div>
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<div class="p">The following debug
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messages are put into the job log:<pre> Current connection is to relational database SYSA.
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DDM job started.
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Optimizer debug messages for distributed query step 1 of 2 follow:
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Temporary distributed result file *QQTDF0001 built for query.
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Following messages created on target system SYSB.
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Arrival sequence access was used for file EMPLOYEE.
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Arrival sequence access was used for file EMPLOYEE.
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Optimizer debug messages for distributed query step 2 of 2 follow:
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Arrival sequence access was used for file EMPLOYEE.
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ODP created.
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Blocking used for query.</pre>
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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="chgqrya.htm" title="The CHGQRYA command has two parameters that are applicable to distributed queries.">Changes to the change query attributes (CHGQRYA) command with DB2 Multisystem</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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