54 lines
3.5 KiB
HTML
54 lines
3.5 KiB
HTML
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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.Type" content="concept" />
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<meta name="DC.Title" content="Spreading data automatically" />
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<meta name="abstract" content="DB2 Universal Database for iSeries automatically spreads the data across the disk devices available in the auxiliary storage pool (ASP) where the data is allocated. This ensures that the data is spread without user intervention." />
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<meta name="description" content="DB2 Universal Database for iSeries automatically spreads the data across the disk devices available in the auxiliary storage pool (ASP) where the data is allocated. This ensures that the data is spread without user intervention." />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<title>Spreading data automatically</title>
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</head>
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<body id="spreaddata"><a name="spreaddata"><!-- --></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">Spreading data automatically</h1>
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<div><p>DB2
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Universal Database™ for iSeries™ automatically spreads the data across the
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disk devices available in the auxiliary storage pool (ASP) where the data
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is allocated. This ensures that the data is spread without user intervention. </p>
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<p>The spreading allows the database manager to easily process the blocks
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of rows on different disk devices in parallel. Even though DB2
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Universal Database for iSeries spreads data across disk devices within an
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ASP, sometimes the allocation of the data extents (contiguous sets of data)
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might not be spread evenly. This occurs when there is uneven allocation of
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space on the devices, or when a new device is added to the ASP. The allocation
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of the table data space may be spread again by saving, deleting, and then
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restoring the table.</p>
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<p>Maintaining an even distribution of data across all of the disk devices
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can lead to better throughput on query processing. The number of disk devices
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used and how the data is spread across these devices is taken into account
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by the optimizer while costing the different plan permutations. </p>
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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="rzajqdta.htm" title="Data access methods are used to process queries and access data.">Data access on DB2 UDB for iSeries: data access paths and methods</a></div>
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</div>
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</div>
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</body>
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