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| <title>14. MySQL</title><link rel="stylesheet" href="css/docbook.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.72.0"><link rel="start" href="manual.html" title="Apache OpenJPA User's Guide"><link rel="up" href="supported_databases.html" title="Appendix 2. Supported Databases"><link rel="prev" href="dbsupport_foxpro.html" title="13. Microsoft FoxPro"><link rel="next" href="dbsupport_oracle.html" title="15. Oracle"></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">14. |
| MySQL |
| </th></tr><tr><td width="20%" align="left"><a accesskey="p" href="dbsupport_foxpro.html">Prev</a> </td><th width="60%" align="center">Appendix 2. |
| Supported Databases |
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| MySQL |
| </h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="dbsupport_mysql.html#dbsupport_mysql_issues">14.1. |
| Known issues with MySQL |
| </a></span></dt></dl></div><div class="example"><a name="example_props_mysql"></a><p class="title"><b>Example 2.14. |
| Example properties for MySQL |
| </b></p><div class="example-contents"><pre class="programlisting"> |
| openjpa.ConnectionDriverName: com.mysql.jdbc.Driver |
| openjpa.ConnectionURL: jdbc:mysql://SERVER_NAME/DB_NAME |
| </pre></div></div><br class="example-break"><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="dbsupport_mysql_issues"></a>14.1. |
| Known issues with MySQL |
| </h3></div></div></div><div class="itemizedlist"><ul type="disc"><li><p> |
| The default table types that MySQL uses do not support transactions, which will |
| prevent OpenJPA from being able to roll back transactions. Use the |
| <code class="literal">InnoDB</code> table type for any tables that OpenJPA will access. |
| </p></li><li><p> |
| MySQL does not support sub-selects in versions prior to 4.1, and are disabled by |
| default. Some operations (such as the <code class="function">isEmpty()</code> method in a |
| query) will fail due to this. If you are using MySQL 4.1 or later, you can lift |
| this restriction by setting the <code class="literal">SupportsSubselect=true</code> |
| parameter of the <a href="ref_guide_conf_jdbc.html#openjpa.jdbc.DBDictionary" title="6.2. openjpa.jdbc.DBDictionary"> |
| openjpa.jdbc.DBDictionary</a> property. |
| </p></li><li><p> |
| Rollback due to database error or optimistic lock violation is not supported |
| unless the table type is one of the MySQL transactional types. Explicit calls to |
| <code class="function">rollback()</code> before a transaction has been committed, |
| however, are always supported. |
| </p></li><li><p> |
| Floats and doubles may lose precision when stored in some datastores. |
| </p></li><li><p> |
| When storing a field of type <code class="classname">java.math.BigDecimal</code>, some |
| datastores will add extraneous trailing 0 characters, causing an equality |
| mismatch between the field that is stored and the field that is retrieved. |
| </p></li><li><p> |
| Some version of the MySQL JDBC driver have a bug that prevents OpenJPA from |
| being able to interrogate the database for foreign keys. Version 3.0.14 (or |
| higher) of the MySQL driver is required in order to get around this bug. |
| </p></li></ul></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="dbsupport_foxpro.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="supported_databases.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="dbsupport_oracle.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">13. |
| Microsoft FoxPro |
| </td><td width="20%" align="center"><a accesskey="h" href="manual.html">Home</a></td><td width="40%" align="right" valign="top"> 15. |
| Oracle |
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