69 lines
4.0 KiB
HTML
69 lines
4.0 KiB
HTML
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<title>CPI4333 - Hashing algorithm used to process join</title>
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<body id="cpi4333"><a name="cpi4333"><!-- --></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">CPI4333 - Hashing algorithm used to process join</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">CPI4333</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 ">Hashing algorithm used to process join.</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 ">The hash join method is typically used for longer running join queries.
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The original query will be subdivided into hash join steps. <p></p>
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Each
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hash join step will be optimized and processed separately. Debug messages
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which explain the implementation of each hash join step follow this message
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in the joblog. <p></p>
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The list below shows the names of the files
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or the table functions used in this query. If the entry is for a file, the
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format of the entry in this list is the number of the hash join step, the
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filename as specified in the query, the member name as specified in the query,
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the filename actually used in the hash join step, and the member name actually
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used in the hash join step. If the entry is for a table function, the format
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of the entry in this list is the number of the hash join step and the function
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name as specified in the query. <p></p>
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If there are two or more
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files or functions listed for the same hash step, then that hash step is implemented
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with nested loop join.</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 ">The hash join method is usually a good implementation choice, however,
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if you want to disallow the use of this method specify ALWCPYDTA(*YES). </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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