Does anyone know why I would get the following exception when using c3p0 as my connection pool up against a MySQL DB? I realize that c3p0 doesn't support the new JDBC3 variants, but is there anything I can do to get around this exception? Maybe there's a param I need to tweak or a different driver I should be using?
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java.lang.IllegalArgumentException: Unexpected number of args to prepareStatement [right now we do not support new JDBC3 variants!]
at com.mchange.v2.c3p0.stmt.ValueIdentityStatementCacheKey._find(ValueIdentityStatementCacheKey.java:79)
at com.mchange.v2.c3p0.stmt.StatementCacheKey.find(StatementCacheKey.java:45)
at com.mchange.v2.c3p0.stmt.GooGooStatementCache.checkoutStatement(GooGooStatementCache.java:90)
at com.mchange.v2.c3p0.impl.C3P0PooledConnection$ProxyConnectionInvocationHandler.invoke(C3P0PooledConnection.java:601)
at com.mchange.v2.c3p0.impl.$Proxy2.prepareStatement(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at net.sf.hibernate.util.GetGeneratedKeysHelper.prepareStatement(GetGeneratedKeysHelper.java:39)
at net.sf.hibernate.impl.BatcherImpl.getPreparedStatement(BatcherImpl.java:246)
at net.sf.hibernate.impl.BatcherImpl.prepareStatement(BatcherImpl.java:61)
at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:524)
at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:432)
at net.sf.hibernate.impl.ScheduledIdentityInsertion.execute(ScheduledIdentityInsertion.java:29)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:906)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:839)
at
*** SNIP ***
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Here's my hibernate.cfg.xml file:

<hibernate-configuration>
<session-factory>

<property name="connection.driver_class">org.gjt.mm.mysql.Driver</property>

<property name="connection.url">jdbc:mysql://localhost:3306/yadda?autoReconnect=true</property>
<property name="connection.username">yadda</property>
<property name="connection.password"></property>

<property name="c3p0.max_size">4</property>
<property name="c3p0.min_size">2</property>
<property name="c3p0.timeout">10000</property>
<property name="c3p0.max_statements">10</property>

<property name="statement_cache.size">0</property>


<property name="show_sql">true</property>
<property name="dialect">net.sf.hibernate.dialect.MySQLDialect</property>

<!-- Mapping files -->
<mapping resource="com/blah/blah/BLAH.hbm.xml"/>

</session-factory>
</hibernate-configuration>
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and I'm using the latest MySQL J driver: mysql-connector-java-3.0.10-stable-bin.jar

Thanks for any help...

Hi.

This is an outright limitation of the present version of c3p0 -- it doesn't have anything to do with MySQL or your JDBC driver. You cannot use Statement-pooling in conjunction with c3p0 if your application uses PreparedStatements that makes use of any of the following JDBC3 features:

- ResultSet holdability
- PreparedStatements returning autogenerated keys
- PreparedStatements generated with explicit rather than default column names
- PreparedStatements generated with explicit rather than default column indexes

The workaround, for the moment, is to turn statement pooling off, by leaving maxStatements set at 0. This limitation will be removed in the next major version of c3p0.

Sorry about this!

Steve Waldman
c3p0 maintainer

May be you should try Proxool ? (http://proxool.sourceforge.net

...by popular demand...

There's an interim release on Sourceforge of c3p0 [c3p0-0.8.4.5] that lifts the API restrictions on the poolable PreparedStatements. The original poster should now be able to turn on statement pooling and run his application without error. (Please try it! If you do have any problems let me know!)

As far as I know, all JDBC 3.0 API that an underlying JDBC driver supports is now supported by c3p0.

smiles,
Steve
(c3p0-maintainer)