89 lines
5.2 KiB
HTML
89 lines
5.2 KiB
HTML
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<title>CPI4330 - &6 tasks used for parallel &10 scan of file &1</title>
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</head>
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<body id="cpi4330"><a name="cpi4330"><!-- --></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">CPI4330 - &6 tasks used for parallel &10 scan of file &1</h1>
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<div>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><thead align="left"><tr><th colspan="2" align="center" valign="middle" id="d0e16">CPI4330</th>
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</tr>
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</thead>
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<tbody><tr valign="middle"><td valign="middle" width="26.02040816326531%" headers="d0e16 ">Message Text:</td>
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<td valign="middle" width="73.9795918367347%" headers="d0e16 ">&6 tasks used for parallel &10 scan of file &1.</td>
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</tr>
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<tr valign="middle"><td valign="middle" width="26.02040816326531%" headers="d0e16 ">Cause Text:</td>
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<td valign="middle" width="73.9795918367347%" headers="d0e16 ">&6 is the average numbers of tasks used for a &10 scan of member &3
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of file &1 in library &2. <p></p>
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If file &1 in library &2
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is a logical file, then member &9 of physical file &7 in library &8
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is the actual file from which records are being selected. <p></p>
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A
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file name starting with *QUERY or *N for the file indicates a temporary result
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file is being used. <p></p>
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The query optimizer has calculated that
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the optimal number of tasks is &5 which was limited for reason code &4.
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The reason code definitions are: <ol><li>The *NBRTASKS parameter value was specified for the DEGREE parameter of
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the <span class="cmdname">CHGQRYA</span> CL command.</li>
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<li>The optimizer calculated the number of tasks which would use all of the
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central processing units (CPU).</li>
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<li>The optimizer calculated the number of tasks which can efficiently run
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in this job's share of the memory pool.</li>
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<li>The optimizer calculated the number of tasks which can efficiently run
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using the entire memory pool</li>
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<li>The optimizer limited the number of tasks to equal the number of disk
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units which contain the file's data.</li>
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</ol>
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The database manager may further limit the number of tasks used if the
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allocation of the file's data is not evenly distributed across disk units.</td>
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</tr>
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<tr valign="middle"><td valign="middle" width="26.02040816326531%" headers="d0e16 ">Recovery Text:</td>
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<td valign="middle" width="73.9795918367347%" headers="d0e16 ">To disallow usage of parallel &10 scan, specify *NONE on the query
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attribute degree. <p></p>
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A larger number of tasks might further
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improve performance. The following actions based on the optimizer reason code
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might allow the optimizer to calculate a larger number: <ol><li>Specify a larger number of tasks value for the DEGREE parameter of the <span class="cmdname">CHGQRYA</span> CL
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command. Start with a value for number of tasks which is a slightly larger
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than &5</li>
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<li>Simplify the query by reducing the number of fields being mapped to the
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result buffer or by removing expressions. Also, try specifying a number of
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tasks as described by reason code 1.</li>
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<li>Specify *MAX for the query attribute DEGREE.</li>
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<li>Increase the size of the memory pool.</li>
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<li>Use the <span class="cmdname">CHGPF</span> CL command or the SQL ALTER statement
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to redistribute the file's data across more disk units.</li>
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</ol>
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</td>
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</tr>
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</tbody>
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</table>
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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="pimes.htm" title="You can evaluate the structure and performance of the given SQL statements in a program using informational messages put in the job log by the database manager.">Query optimization performance information messages</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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