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| <title>9. Statement Batching</title><base href="display"><link rel="stylesheet" type="text/css" href="css/docbook.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="manual.html" title="Apache OpenJPA 2.4 User's Guide"><link rel="up" href="ref_guide_dbsetup.html" title="Chapter 4. JDBC"><link rel="prev" href="ref_guide_dbsetup_retain.html" title="8. Configuring the Use of JDBC Connections"><link rel="next" href="ref_guide_dbsetup_lrs.html" title="10. Large Result Sets"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">9. |
| Statement Batching |
| </th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ref_guide_dbsetup_retain.html">Prev</a> </td><th width="60%" align="center">Chapter 4. |
| JDBC |
| </th><td width="20%" align="right"> <a accesskey="n" href="ref_guide_dbsetup_lrs.html">Next</a></td></tr></table><hr></div><div class="section" id="ref_guide_dbsetup_stmtbatch"><div class="titlepage"><div><div><h2 class="title" style="clear: both">9. |
| Statement Batching |
| </h2></div></div></div> |
| |
| <a class="indexterm" name="d5e11691"></a> |
| <a class="indexterm" name="d5e11693"></a> |
| <p> |
| In addition to connection pooling and prepared statement caching, OpenJPA |
| employs statement batching to speed up JDBC updates. Statement batching is |
| enabled by default for any JDBC driver that supports it. When batching is on, |
| OpenJPA automatically orders its SQL statements to maximize the size of each |
| batch. This can result in large performance gains for transactions that modify |
| a lot of data. |
| </p> |
| <p> |
| You configure statement batching through the system DBDictionary, which is |
| controlled by the openjpa.jdbc.DBDictionary configuration property. You can |
| enable the statement batching by setting the batchLimit in the value. The batch |
| limit is the maximum number of statements OpenJPA will ever batch |
| together. A value has the following meaning: |
| </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"> |
| <p> |
| <code class="literal">-1</code>: Unlimited number of statements for a batch. |
| </p> |
| </li><li class="listitem"> |
| <p> |
| <code class="literal">0</code>: Disable batch support. This is the default for most |
| dictionaries. |
| </p> |
| </li><li class="listitem"> |
| <p> |
| <code class="literal">any positive number</code>: Maximum number of statements for a batch. |
| </p> |
| </li></ul></div><p> |
| </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> |
| <p> |
| By default, the batch support is based on each Dictionary to define the default |
| batch limit. Currently only DB2 and Oracle dictionaries are set the default |
| batch limit to 100. The default batch limit for the rest of the dictionaries is set |
| to zero (disabled). |
| </p> |
| </div><p> |
| </p> |
| <p> |
| The example below shows how to enable and disable statement batching via |
| your configuration properties. |
| </p> |
| <div class="example" id="ref_guide_dbsetup_stmtbatch_exmple1"><p class="title"><b>Example 4.13. |
| Enable SQL statement batching |
| </b></p><div class="example-contents"> |
| |
| <pre class="programlisting"> |
| <property name="openjpa.jdbc.DBDictionary" value="db2(batchLimit=25)"/> |
| <property name="openjpa.jdbc.DBDictionary" value="oracle(batchLimit=-1)"/> |
| Or |
| <property name="openjpa.jdbc.DBDictionary" value="batchLimit=25"/> |
| <property name="openjpa.jdbc.DBDictionary" value="batchLimit=-1"/> |
| </pre> |
| </div></div><br class="example-break"> |
| <div class="example" id="ref_guide_dbsetup_stmtbatch_exmple2"><p class="title"><b>Example 4.14. |
| Disable SQL statement batching |
| </b></p><div class="example-contents"> |
| |
| <pre class="programlisting"> |
| <property name="openjpa.jdbc.DBDictionary" value="db2(batchLimit=0)"/> |
| Or |
| <property name="openjpa.jdbc.DBDictionary" value="batchLimit=0"/> |
| </pre> |
| </div></div><br class="example-break"> |
| <p> |
| By default, org.apache.openjpa.jdbc.kernel.BatchingConstraintUpdateManager |
| is the default statement batching implementation. OPENJPA also |
| provides another update manager |
| org.apache.openjpa.jdbc.kernel.BatchingOperationOrderUpdateManager for the |
| statements that required ordering. You can plug-in this update manager through |
| the "openjpa.jdbc.UpdateManager" property. Or you can plug-in your own |
| statement batching implementation by providing the implementation that extends |
| from AbstractUpdateManager, ConstraitUpdateManager or OperationOrderUpdateManager. |
| Add this implementation |
| class as a property in the persistence.xml file. For example, a custom |
| statement batching implementation mycomp.MyUpdateManager extends |
| ConstraitUpdateManager. You specify this implementation in the persistence.xml |
| file as the following example: |
| </p> |
| <div class="example" id="ref_guide_dbsetup_stmtbatch_exmple3"><p class="title"><b>Example 4.15. |
| Plug-in custom statement batching implementation |
| </b></p><div class="example-contents"> |
| |
| <pre class="programlisting"> |
| <property name="openjpa.jdbc.UpdateManager" value="mycomp.MyUpdateManager"/> |
| </pre> |
| </div></div><br class="example-break"> |
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| Configuring the Use of JDBC Connections |
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| Large Result Sets |
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