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Subject [CONF] OpenJPA > Fetch Statistics
Date Tue, 10 Jul 2012 21:24:00 GMT
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    <h2><a href="">Fetch
    <h4>Page <b>edited</b> by             <a href="">Helen
                         <h4>Changes (2)</h4>
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            <tr><td class="diff-snipped" >...<br></td></tr>
            <tr><td class="diff-unchanged" >h3. Usage <br> <br></td></tr>
            <tr><td class="diff-added-lines" style="background-color: #dfd;">Standard
JVM usage <br> <br></td></tr>
            <tr><td class="diff-unchanged" >* Configuration <br> <br></td></tr>
            <tr><td class="diff-snipped" >...<br></td></tr>
            <tr><td class="diff-unchanged" >&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
  Remove openjpa-fetch-statistics-version-SNAPSHOT.jar from the classpath. <br> <br></td></tr>
            <tr><td class="diff-changed-lines" ><span class="diff-deleted-words"style="color:#999;background-color:#fdd;text-decoration:line-through;">&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;</span>
Here is the [Usage for Websphere Application Server] <br></td></tr>
            <tr><td class="diff-unchanged" > <br> <br></td></tr>
            <tr><td class="diff-snipped" >...<br></td></tr>
    </div>                            <h4>Full Content</h4>
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        <h1><a name="FetchStatistics-FetchStatistics"></a>Fetch Statistics</h1>

<p>Open JPA Fetch Statistics Tool monitors persistent field access and determines which
fields are never used. This tool<br/>
can be used to help tune an application.</p>

<h3><a name="FetchStatistics-Note"></a>Note</h3>

	<li>Open JPA Fetch Statistics Tool works with the runtime enhancement.</li>

	<li>Only the persistent fields which satisfy all the following conditions will be tracked
by the tool:
		<li>The field has EAGER fetch mode.</li>
		<li>The field is not primary key.</li>
		<li>The field is not defined as a version field.</li>

<h3><a name="FetchStatistics-Download"></a>Download</h3>

<p>The latest OpenJPA Tools JAR file can be download from the <a href=""
class="external-link" rel="nofollow">SNAPSHOT Repository</a> or can be built from
the source code in <a href="" class="external-link"
rel="nofollow">svn</a> by using Maven 2.2.1 and Java SE 6.</p>

<h3><a name="FetchStatistics-Usage"></a>Usage</h3>

<p>Standard JVM usage</p>


 Append the path of openjpa-fetch-statistics-version-SNAPSHOT.jar file to the classpath prior
to lanuching the JVM.</p>

	<li>Statistics Collecting and Monitoring</li>

When this tool is configured, it will be active for all persistence units in the JVM. Statistics
will be dumped via the<br/>
  openjpa.Runtime channel with the INFO level every 10 minutes, or when the JVM terminates.
Any EAGER field that is logged<br/>
  has not been accessed by an application.</p>

	<li>Configuration removal</li>

 Stop the JVM.<br/>
  Remove openjpa-fetch-statistics-version-SNAPSHOT.jar from the classpath.</p>

<p>Here is the <a href="/confluence/display/openjpa/Usage+for+Websphere+Application+Server"
title="Usage for Websphere Application Server">Usage for Websphere Application Server</a></p>

<h3><a name="FetchStatistics-PerformanceConsideration"></a>Performance Consideration</h3>

<p>There will be a large performance impact when running this tooling. It is not supported,
nor recommended for production use. This tool should not be used on a production machine.</p>
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