I have a JPA/Hibernate application and am trying to get it to run against H2 and MySQL. Currently I am using Atomikos for transactions and C3P0 for connection pooling.

Despite my best efforts I am still seeing this in the log file (and DAO integration tests are failing with org.hibernate.NonUniqueObjectException even though Spring Test should be rolling back the database after each test method):

[20100613 23:06:34] DEBUG [main] SessionFactoryImpl.(242) | instantiating session factory with properties: .....edited for brevity.... hibernate.connection.autocommit=true, ....more stuff follows

The connection URL to H2 has AUTOCOMMIT=OFF, but according to the H2 documentation:

this will not work as expected when using a connection pool (the connection pool manager will re-enable autocommit when returning the connection to the pool, so autocommit will only be disabled the first time the connection is used

So I figured (apparently correctly) that Hibernate is where I'll have to indicate I want autocommit off. I found the autocommit property documented here and I put it in my EntityManagerFactory config as follows:

<bean id="myappTestLocalEmf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="myapp-core" />
        <property name="persistenceUnitPostProcessors">
            <bean class="com.myapp.core.persist.util.JtaPersistenceUnitPostProcessor">
                <property name="jtaDataSource" ref="myappPersistTestJdbcDataSource" />
            </bean>
        </property>

        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="showSql" value="true" />
                <property name="database" value="$DS{hibernate.database}" />
                <property name="databasePlatform" value="$DS{hibernate.dialect}" />
            </bean>
        </property>

        <property name="jpaProperties">
            <props>
                <prop key="hibernate.transaction.factory_class">com.atomikos.icatch.jta.hibernate3.AtomikosJTATransactionFactory</prop>
                <prop key="hibernate.transaction.manager_lookup_class">com.atomikos.icatch.jta.hibernate3.TransactionManagerLookup</prop>
                <prop key="hibernate.connection.autocommit">false</prop>
                <prop key="hibernate.format_sql">true"</prop>
                <prop key="hibernate.use_sql_comments">true</prop>
    </property>
</bean>