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121 lines
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<meta name="abstract" content="Determine which queries in your SQL application are implemented with table scans. The complete information can be obtained by joining two views: QQQ1000, which contains information about the SQL statements, and QQQ3000, which contains data about queries performing table scans." />
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<title>Database monitor performance analysis example 1</title>
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<body id="rzajqmon1"><a name="rzajqmon1"><!-- --></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">Database monitor performance analysis example 1</h1>
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<div><p>Determine which queries in your SQL application are implemented
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with table scans. The complete information can be obtained by joining two
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views: QQQ1000, which contains information about the SQL statements, and QQQ3000,
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which contains data about queries performing table scans.</p>
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<div class="section"><p>The following SQL query can be used: </p>
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<pre><strong>SELECT</strong> A.System_Table_Schema, A.System_Table_Name, A.Table_Total_Rows, A.Index_Advised,
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C.Number_Rows_Returned, (B.End_Timestamp - B.Start_Timestamp)
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<strong>AS</strong> TOT_TIME, B.Statement_Text_Long
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<strong>FROM</strong> LIB/QQQ3000 A, LIB/QQQ1000 B, LIB/QQQ3019 C
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<strong>WHERE</strong> A.Join_Column = B.Join_Column
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<strong>AND</strong> A.Unique_Count = B.Unique_Count
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<strong>AND</strong> A.Join_Column = C.Join_Column
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<strong>AND</strong> A.Unique_Count = C.Unique_Count </pre>
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</div>
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<div class="section"><p>Sample output of this query is shown in the table below. Key to
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this example are the join criteria: </p>
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<pre> <strong>WHERE</strong> A.Join_Column = B.Join_Column
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<strong>AND</strong> A.Join_Column = C.Join_Column</pre>
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</div>
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<div class="section"><p>A lot of data about many queries is contained in multiple rows
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in table LIB/PERFDATA. It is not uncommon for data about a single query to
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be contained in 10 or more rows within the table. The combination of defining
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the logical views and then joining the views together allows you to piece
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together all the data for a query or set of queries. Column QQJFLD uniquely
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identifies all queries within a job; column QQUCNT is unique at the query
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level. The combination of the two, when referenced in the context of the logical
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views, connects the query implementation to the query statement information.</p>
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</div>
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<table cellpadding="4" cellspacing="0" border="1" class="tableborder"><tr><td>
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<a name="rzajqmon1__tblscn"><!-- --></a><table cellpadding="4" cellspacing="0" summary="" id="rzajqmon1__tblscn" width="100%" border="0"><caption>Table 1. Output for
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SQL Queries that Performed Table Scans</caption><thead align="left"><tr><th align="left" valign="bottom" width="10%" id="d0e81">Lib Name</th>
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<th align="left" valign="bottom" width="10%" id="d0e83">Table Name</th>
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<th align="left" valign="bottom" width="10%" id="d0e85">Total Rows</th>
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<th align="left" valign="bottom" width="10%" id="d0e87">Index Advised</th>
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<th align="left" valign="bottom" width="10%" id="d0e89">Rows Returned</th>
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<th align="left" valign="bottom" width="10%" id="d0e91">TOT_ TIME</th>
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<th align="left" valign="bottom" width="40%" id="d0e93">Statement Text</th>
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</tr>
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</thead>
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<tbody><tr><td align="left" valign="top" width="10%" headers="d0e81 "><strong>LIB1</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e83 "><strong>TBL1</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e85 "><strong>20000</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e87 "><strong>Y</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e89 "><strong>10</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e91 "><strong>6.2</strong></td>
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<td align="left" valign="top" width="40%" headers="d0e93 "><pre>SELECT * FROM LIB1/TBL1
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WHERE FLD1 = 'A'</pre>
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</td>
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</tr>
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<tr><td align="left" valign="top" width="10%" headers="d0e81 "><strong>LIB1</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e83 "><strong>TBL2</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e85 "><strong>100</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e87 "><strong>N</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e89 "><strong>100</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e91 "><strong>0.9</strong></td>
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<td align="left" valign="top" width="40%" headers="d0e93 "><pre>SELECT * FROM LIB1/TBL2</pre>
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</td>
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</tr>
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<tr><td align="left" valign="top" width="10%" headers="d0e81 "><strong>LIB1</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e83 "><strong>TBL1</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e85 "><strong>20000</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e87 "><strong>Y</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e89 "><strong>32</strong></td>
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<td align="left" valign="top" width="10%" headers="d0e91 "><strong>7.1</strong></td>
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<td align="left" valign="top" width="40%" headers="d0e93 "><pre>SELECT * FROM LIB1/TBL1
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WHERE FLD1 = 'B' AND
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FLD2 > 9000</pre>
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</td>
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</tr>
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</tbody>
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</table>
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</td></tr></table>
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<div class="section"><p>If the query does not use SQL, the SQL information row (QQQ1000)
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is not created. This makes it more difficult to determine which rows in LIB/PERFDATA
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pertain to which query. When using SQL, row QQQ1000 contains the actual SQL
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statement text that matches the monitor rows to the corresponding query. Only
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through SQL is the statement text captured. For queries executed using the
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OPNQRYF command, the OPNID parameter is captured and can be used to tie the
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rows to the query. The OPNID is contained in column Open_Id of row QQQ3014.</p>
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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="dbmonexamples.htm" title="The iSeries navigator interface provides a powerful tool for gathering and analyzing performance monitor data using database monitor. However, you may want to do your own analysis of the database monitor files.">Database monitor examples</a></div>
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</div>
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</div>
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</body>
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