80 lines
5.0 KiB
HTML
80 lines
5.0 KiB
HTML
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<meta name="abstract" content="The database objects and access methods used by the query engine can be broken down into three basic types of operations that are used to manipulate the permanent and temporary objects -- Create, Scan, and Probe." />
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<title>Permanent objects and access methods</title>
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<body id="rzajqpermobj"><a name="rzajqpermobj"><!-- --></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">Permanent objects and access methods</h1>
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<div><p>The database objects and access methods used by the query engine
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can be broken down into three basic types of operations that are used to manipulate
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the permanent and temporary objects -- Create, Scan, and Probe.</p>
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<div class="section"><p>The following table lists each object and the access methods that
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can be performed against that object. The symbols shown in the table are the
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icons used by Visual Explain. </p>
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</div>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 1. Permanent object's data access methods</caption><thead align="left"><tr><th valign="top" id="d0e33">Permanent objects </th>
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<th valign="top" id="d0e35">Scan operations</th>
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<th valign="top" id="d0e37">Probe operations</th>
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</tr>
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</thead>
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<tbody><tr><td valign="top" headers="d0e33 ">Table</td>
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<td valign="top" headers="d0e35 ">Table scan</td>
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<td valign="top" headers="d0e37 ">Table probe</td>
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</tr>
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<tr><td valign="top" headers="d0e33 ">Radix index</td>
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<td valign="top" headers="d0e35 ">Radix index scan</td>
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<td valign="top" headers="d0e37 ">Radix index probe</td>
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</tr>
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<tr><td valign="top" headers="d0e33 ">Encoded vector index</td>
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<td valign="top" headers="d0e35 ">Encoded vector index symbol table scan</td>
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<td valign="top" headers="d0e37 ">Encoded vector index probe</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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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rzajqcrttbl.htm">Table</a></strong><br />
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An SQL table or physical file is the base object for a query. It represents the source of the data used to produce the result set for the query. It is created by the user and specified in the FROM clause (or OPNQRYF FILE parameter).</li>
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<li class="ulchildlink"><strong><a href="perf21b.htm">Radix index</a></strong><br />
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An SQL index (or keyed sequence access path) is a permanent object that is created over a table and used by the optimizer to provide a sequenced view of the data for a scan or probe operation.</li>
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<li class="ulchildlink"><strong><a href="perf21c.htm">Encoded vector index</a></strong><br />
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An encoded vector index is a permanent object that provides access to a table by assigning codes to distinct key values and then representing those values in a vector.</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="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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</body>
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