Documentation on QueryCache Statistics

git-svn-id: https://svn.apache.org/repos/asf/openjpa/trunk@939447 13f79535-47bb-0310-9956-ffa450edef68
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Pinaki Poddar 2010-04-29 18:36:37 +00:00
parent d43fea80d8
commit 4fec004e9d
1 changed files with 10 additions and 3 deletions
openjpa-project/src/doc/manual

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@ -1146,7 +1146,7 @@ Disables the compilation cache.
</indexterm>
<para>
Prepared SQL Cache caches SQL statements corresponding to JPQL queries.
If a JPQL query is executed more than once in the same or different persistence
If a query is executed more than once in the same or different persistence
contexts, the SQL statement generated during the first execution is cached and
executed directly for subsequent execution. Direct execution of SQL offers
significant performance gain as it saves the cost of parsing query string and,
@ -1164,7 +1164,14 @@ Prepared SQL Cache is configured by the <link linkend="openjpa.jdbc.QuerySQLCach
<literal>openjpa.jdbc.QuerySQLCache</literal></link> configuration property. This
property accepts a plugin string (see <xref linkend="ref_guide_conf_plugins"/>)
with value of <literal>true</literal> or <literal>false</literal>. The default
is <literal>true</literal>.
is <literal>true</literal>. The execution statistics of the cached queries can be
optionally collected as
<programlisting>
&lt;property name="openjpa.jdbc.QuerySQLCache" value="true(EnableStatistics=true)"&gt;
</programlisting>
The <ulink url="../javadoc/org/apache/openjpa/kerenl/QueryStatistics.html">
<code>QueryStatistics</code></ulink> can be accessed via <code>PreparedQueryCache.getStatistics()</code>.
</para>
<table>
<title>
@ -1250,7 +1257,7 @@ Following salient points to be noted regarding usage of Prepared Query Cache.
<programlisting>
String jpql = "SELECT p FROM Person p WHERE p.name=:name";
List johns = em.createQuery(jpql).setParameter("name","John").getResultList();
List toms = em.createQuery(jpql).setParameter("name","John").getResultList();
List toms = em.createQuery(jpql).setParameter("name","Tom").getResultList();
</programlisting>
</example>
</para>