115 lines
8.2 KiB
HTML
115 lines
8.2 KiB
HTML
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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>Temporary objects and access methods</title>
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</head>
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<body id="rzajqtempobj"><a name="rzajqtempobj"><!-- --></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">Temporary objects and access methods</h1>
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<div><p>Temporary objects are created by the optimizer in order to process
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a query. In general, these temporary objects are internal objects and cannot
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be accessed by a user.</p>
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<div class="tablenoborder"><img src="./delta.gif" alt="Start of change" /><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 1. Temporary object's data access methods</caption><thead align="left"><tr><th valign="top" id="d0e30">Temporary create objects</th>
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<th valign="top" id="d0e32">Scan operations</th>
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<th valign="top" id="d0e34">Probe operations</th>
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</tr>
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</thead>
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<tbody><tr><td valign="top" headers="d0e30 ">Temporary hash table</td>
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<td valign="top" headers="d0e32 ">Hash table scan</td>
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<td valign="top" headers="d0e34 ">Hash table probe</td>
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</tr>
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<tr><td valign="top" headers="d0e30 ">Temporary sort list</td>
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<td valign="top" headers="d0e32 ">Sorted list scan</td>
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<td valign="top" headers="d0e34 ">Sorted list probe</td>
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</tr>
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<tr><td valign="top" headers="d0e30 ">Temporary list</td>
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<td valign="top" headers="d0e32 ">List scan</td>
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<td valign="top" headers="d0e34 ">N/A</td>
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</tr>
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<tr><td valign="top" headers="d0e30 ">Temporary row number list</td>
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<td valign="top" headers="d0e32 ">Row number list scan</td>
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<td valign="top" headers="d0e34 ">Row number list probe</td>
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</tr>
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<tr><td valign="top" headers="d0e30 ">Temporary bitmap</td>
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<td valign="top" headers="d0e32 ">Bitmap scan</td>
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<td valign="top" headers="d0e34 ">Bitmap probe</td>
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</tr>
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<tr><td valign="top" headers="d0e30 ">Temporary index</td>
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<td valign="top" headers="d0e32 ">Temporary index scan</td>
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<td valign="top" headers="d0e34 ">Temporary index probe</td>
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</tr>
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<tr><td valign="top" headers="d0e30 ">Temporary buffer</td>
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<td valign="top" headers="d0e32 ">Buffer scan</td>
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<td valign="top" headers="d0e34 ">N/A</td>
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</tr>
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<tr><td valign="top" headers="d0e30 ">Queue</td>
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<td valign="top" headers="d0e32 ">N/A</td>
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<td valign="top" headers="d0e34 ">N/A</td>
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</tr>
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</tbody>
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</table>
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<img src="./deltaend.gif" alt="End of change" /></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="rzajqtemphash.htm">Temporary hash table</a></strong><br />
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The temporary hash table is a temporary object that allows the optimizer to collate the rows based upon a column or set of columns. The hash table can be either scanned or probed by the optimizer to satisfy different operations of the query.</li>
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<li class="ulchildlink"><strong><a href="rzajqtempslist.htm">Temporary sorted list</a></strong><br />
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The temporary sorted list is a temporary object that allows the optimizer to sequence rows based upon a column or set of columns. The sorted list can be either scanned or probed by the optimizer to satisfy different operations of the query.</li>
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<li class="ulchildlink"><strong><a href="rzajqtemplist.htm">Temporary list</a></strong><br />
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The temporary list is a temporary object that allows the optimizer to store intermediate results of a query. The list is an unsorted data structure that is used to simplify the operation of the query. Since the list does not have any keys, the rows within the list can only be retrieved by a sequential scan operation.</li>
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<li class="ulchildlink"><strong><a href="rzajqtemprnl.htm">Temporary row number list</a></strong><br />
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The temporary row number list is a temporary object that allows the optimizer to sequence rows based upon their row address (their row number). The row number list can be either scanned or probed by the optimizer to satisfy different operations of the query.</li>
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<li class="ulchildlink"><strong><a href="rzajqtempbit.htm">Temporary bitmap</a></strong><br />
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The temporary bitmap is a temporary object that allows the optimizer to sequence rows based upon their row address (their row number). The bitmap can be either scanned or probed by the optimizer to satisfy different operations of the query.</li>
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<li class="ulchildlink"><strong><a href="rzajqtempindex.htm">Temporary index</a></strong><br />
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A temporary index is a temporary object that allows the optimizer
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to create and use a radix index for a specific query. The temporary index
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has all of the same attributes and benefits as a radix index that is created
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by a user through the CREATE INDEX SQL statement or <span class="cmdname">Create Logical
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File (CRTLF)</span> CL command.</li>
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<li class="ulchildlink"><strong><a href="rzajqtempbuff.htm">Temporary buffer</a></strong><br />
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The temporary buffer is a temporary object that is used to help facilitate operations such as parallelism. It is an unsorted data structure that is used to store intermediate rows of a query. The main difference between a temporary buffer and a temporary list is that the buffer does not need to be fully populated in order to allow its results to be processed.</li>
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<li class="ulchildlink"><strong><a href="rzajqqueue.htm">Queue</a></strong><br />
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The Queue is a temporary object that allows the optimizer to feed the recursion of a recursive query by putting on the queue those data values needed for the recursion. This data typically includes those values used on the recursive join predicate and other recursive data being accumulated or manipulated during the recursive process.</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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</div>
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</body>
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</html>
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