112 lines
7.2 KiB
HTML
112 lines
7.2 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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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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<meta name="DC.Title" content="Starting a summary monitor" />
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<meta name="abstract" content="You can start a summary monitor from the iSeries Navigator interface." />
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<meta name="description" content="You can start a summary monitor from the iSeries Navigator interface." />
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<meta name="DC.Relation" scheme="URI" content="rzajqnavsummon.htm" />
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<meta name="DC.Relation" scheme="URI" content="indexstats.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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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>Starting a summary monitor</title>
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</head>
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<body id="rzajqstartsummon"><a name="rzajqstartsummon"><!-- --></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">Starting a summary monitor</h1>
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<div><p>You can start a summary monitor from the iSeries™ Navigator interface.</p>
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<div class="section"></div>
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<div class="section"><p>You can start this monitor by right-clicking SQL Performance Monitors
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under the Database portion of the iSeries Navigator tree and selecting <span class="menucascade"><span class="uicontrol">New</span> > <span class="uicontrol">SQL Performance Monitor</span></span>.
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In the monitor wizard, select <strong>Summary</strong>.</p>
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<p>When you create a summary
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monitor, certain kinds of information are always collected. This information
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includes summary information, SQL statement information, and host variable
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information. You can also choose to collect the following types of information:</p>
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</div>
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<div class="section"><dl><dt class="dlterm">Table scans and arrival sequences</dt>
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<dd>Select to include information about table scan data for the monitored
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jobs. Table scans of large tables can be time-consuming. If the SQL statement
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is long running, it may indicate that an index might be necessary to improve
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performance.</dd>
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<dt class="dlterm">Indexes used</dt>
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<dd>Select to include information about how indexes are used by monitored
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jobs. This information can be used to quickly tell if any of the permanent
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indexes were used to improve the performance of a query. Permanent indexes
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are typically necessary to achieve optimal query performance. This information
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can be used to determine how often a permanent index was used by in the statements
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that were monitored. Indexes that are never (or very rarely) used should probably
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be dropped to improve the performance of inserts updates and deletes to a
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table. Before dropping the index, you may want to determine if the index is
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being used by the query optimizer as a source of statistics.</dd>
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<dt class="dlterm">Index creation</dt>
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<dd>Select to include information about the creation of indexes by monitored
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jobs. Temporary indexes may need to be created for several reasons such as
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to perform a join, to support scrollable cursors, to implement ORDER BY or
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GROUP BY, and so on. The created indexes may only contain keys for rows that
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satisfy the query (such indexes are known as sparse indexes). In many cases,
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the index create may be perfectly normal and the most efficient way to perform
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the query. However, if the number of rows is large, or if the same index is
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repeatedly created, you may be able to create a permanent index to improve
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performance of this query. This may be true whether an index was advised.</dd>
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<dt class="dlterm">Data sorts</dt>
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<dd>Select to include information about data sorts that monitored jobs perform.
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Sorts of large result sets in an SQL statement may be a time consuming operation.
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In some cases, an index can be created that will eliminate the need for a
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sort.</dd>
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<dt class="dlterm">Temporary file use</dt>
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<dd>Select to include information about temporary files that monitored jobs
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created. Temporary results are sometimes necessary based on the SQL statement.
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If the result set inserted into a temporary result is large, you may want
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to investigate why the temporary result is necessary. In some cases, the SQL
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statement can be modified to eliminate the need for the temporary result.
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For example, if a cursor has an attribute of INSENSITIVE, a temporary result
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will be created. Eliminating the keyword INSENSITIVE will typically remove
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the need for the temporary result, but your application will then see changes
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as they are occur in the database tables.</dd>
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<dt class="dlterm">Indexes considered</dt>
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<dd>Select to include information about which indexes were considered for
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the monitored jobs. This information can help to determine if an index is
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used in the query. If an index was considered, but not used, you might need
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to rewrite the index or drop it. Before dropping the index, you may want to
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determine if the index is being used by the query optimizer as a source of
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statistics.</dd>
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<dt class="dlterm">Subselect processing</dt>
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<dd>Select to include information about subselect processing. This information
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can indicate which subquery in a complex SQL statement is the most expensive.</dd>
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</dl>
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</div>
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<div class="section"><p>You can choose which jobs you want to monitor or choose to monitor
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all jobs. You can have multiple instances of monitors running on you system
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at one time. For summary monitors, only one monitor instance can be monitoring
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all jobs. Additionally, you cannot have two monitors monitoring the same job.
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When collecting information for all jobs, the monitor will collect on previously
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started jobs or new jobs started after the monitor is created. You can edit
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this list by selecting and removing jobs from the <strong>Selected jobs</strong> list.</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="rzajqnavsummon.htm" title="You can work with summary monitors from the iSeries Navigator interface. A summary monitor creates a Memory-Resident Database monitor (DBMon), found on the native interface.">Using iSeries Navigator with summary monitors</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="indexstats.htm" title="You can easily determine which indexes are being used for query optimization.">Determining unnecessary indexes</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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