Confusing conflicts between OpenJPA and Postgresql

Hi all,
I'm recently doing some research with Apache ODE engine. I use Postgresql as its external database, openjpa as its ORM solution and bitronix as its transaction manager. The ODE workflow engine starts without any problem. But when I deploy process definition files into the engine, the exception came out. I paste the error content at the end of this email.
I looked through the source code of org.apache.openjpa.lib.jdbc.DecoratingDataSource, and found that openjpa is almost definitely to meant to invoke the function of reseting transaction isolation level, which would be catched by Postgresql and return with an exception.
Does that mean openjpa works poorly with Postgresql? Or who can tell me how to solve this problem.
The error content is below:
17:32:05,155 ERROR [ProcessStoreImpl] Error persisting deployment record for {http://sample.bpel.org/bpel/sample}longFlow-1; process will not be available after restart!
<openjpa-1.2.1-r752877:753278 nonfatal general error> org.apache.openjpa.persistence.PersistenceException: Cannot change transaction isolation level in the middle of a transaction
at org.apache.openjpa.jdbc.sql.DBDictionary.narrow(DBDictionary.java:4232)
at org.apache.openjpa.jdbc.sql.DBDictionary.newStoreException(DBDictionary.java:4197)
at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:102)
at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:88)
at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:64)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.connect(JDBCStoreManager.java:930)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.getConnection(JDBCStoreManager.java:230)
at org.apache.openjpa.jdbc.sql.SelectImpl.execute(SelectImpl.java:371)
at org.apache.openjpa.jdbc.sql.SelectImpl.execute(SelectImpl.java:339)
at org.apache.openjpa.jdbc.sql.LogicalUnion$UnionSelect.execute(LogicalUnion.java:420)
at org.apache.openjpa.jdbc.sql.LogicalUnion.execute(LogicalUnion.java:230)
at org.apache.openjpa.jdbc.sql.LogicalUnion.execute(LogicalUnion.java:220)
at org.apache.openjpa.jdbc.sql.LogicalUnion.execute(LogicalUnion.java:206)
at org.apache.openjpa.jdbc.kernel.SelectResultObjectProvider.open(SelectResultObjectProvider.java:94)
at org.apache.openjpa.lib.rop.WindowResultList.<init>(WindowResultList.java:57)
at org.apache.openjpa.jdbc.kernel.JDBCFetchConfigurationImpl.newResultList(JDBCFetchConfigurationImpl.java:235)
at org.apache.openjpa.kernel.QueryImpl.toResult(QueryImpl.java:1228)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:990)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:805)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:775)
at org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:771)
at org.apache.openjpa.kernel.DelegatingQuery.execute(DelegatingQuery.java:517)
at org.apache.openjpa.persistence.QueryImpl.execute(QueryImpl.java:255)
at org.apache.openjpa.persistence.QueryImpl.getResultList(QueryImpl.java:294)
at org.apache.ode.store.jpa.ConfStoreConnectionJpa.setVersion(ConfStoreConnectionJpa.java:76)
at org.apache.ode.store.ProcessStoreImpl$2.call(ProcessStoreImpl.java:294)
at org.apache.ode.store.ProcessStoreImpl$2.call(ProcessStoreImpl.java:264)
at org.apache.ode.store.ProcessStoreImpl$Callable.call(ProcessStoreImpl.java:793)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: org.postgresql.util.PSQLException: Cannot change transaction isolation level in the middle of a transaction
at org.postgresql.jdbc2.AbstractJdbc2Connection.setTransactionIsolation(AbstractJdbc2Connection.java:944)
at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at bitronix.tm.resource.jdbc.BaseProxyHandlerClass.invoke(BaseProxyHandlerClass.java:64)
at $Proxy5.setTransactionIsolation(Unknown Source)
at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at bitronix.tm.resource.jdbc.BaseProxyHandlerClass.invoke(BaseProxyHandlerClass.java:64)
at $Proxy7.setTransactionIsolation(Unknown Source)
at org.apache.openjpa.lib.jdbc.DelegatingConnection.setTransactionIsolation(DelegatingConnection.java:257)
at org.apache.openjpa.lib.jdbc.ConfiguringConnectionDecorator.decorate(ConfiguringConnectionDecorator.java:95)
at org.apache.openjpa.lib.jdbc.DecoratingDataSource.decorate(DecoratingDataSource.java:100)
at org.apache.openjpa.lib.jdbc.DecoratingDataSource.getConnection(DecoratingDataSource.java:88)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.connectInternal(JDBCStoreManager.java:941)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.connect(JDBCStoreManager.java:926)
... 27 more
17:32:05,163 ERROR [ProcessStoreImpl] DbError
java.lang.RuntimeException: java.lang.IllegalStateException: no transaction started on this thread
at org.apache.ode.store.jpa.DbConfStoreConnectionFactory.rollbackTransaction(DbConfStoreConnectionFactory.java:96)
at org.apache.ode.store.ProcessStoreImpl$Callable.call(ProcessStoreImpl.java:800)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.IllegalStateException: no transaction started on this thread
at bitronix.tm.BitronixTransactionManager.rollback(BitronixTransactionManager.java:150)
at org.apache.ode.store.jpa.DbConfStoreConnectionFactory.rollbackTransaction(DbConfStoreConnectionFactory.java:94)
... 6 more
17:32:05,163 ERROR [DeploymentPoller] Deployment of LongFlow failed, aborting for now.
org.apache.ode.bpel.iapi.ContextException: DbError
at org.apache.ode.store.ProcessStoreImpl.exec(ProcessStoreImpl.java:618)
at org.apache.ode.store.ProcessStoreImpl.deploy(ProcessStoreImpl.java:264)
at org.apache.ode.store.ProcessStoreImpl.deploy(ProcessStoreImpl.java:172)
at org.apache.ode.axis2.deploy.DeploymentPoller.check(DeploymentPoller.java:160)
at org.apache.ode.axis2.deploy.DeploymentPoller.access$300(DeploymentPoller.java:60)
at org.apache.ode.axis2.deploy.DeploymentPoller$PollingThread.run(DeploymentPoller.java:251)
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: bitronix.tm.internal.BitronixRollbackException: RuntimeException thrown during beforeCompletion cycle caused transaction rollback
at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222)
at java.util.concurrent.FutureTask.get(FutureTask.java:83)
at org.apache.ode.store.ProcessStoreImpl.exec(ProcessStoreImpl.java:616)
... 5 more
Caused by: java.lang.RuntimeException: bitronix.tm.internal.BitronixRollbackException: RuntimeException thrown during beforeCompletion cycle caused transaction rollback
at org.apache.ode.store.jpa.DbConfStoreConnectionFactory.commitTransaction(DbConfStoreConnectionFactory.java:87)
at org.apache.ode.store.ProcessStoreImpl$Callable.call(ProcessStoreImpl.java:794)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: bitronix.tm.internal.BitronixRollbackException: RuntimeException thrown during beforeCompletion cycle caused transaction rollback
at bitronix.tm.BitronixTransaction.commit(BitronixTransaction.java:241)
at bitronix.tm.BitronixTransactionManager.commit(BitronixTransactionManager.java:143)
at org.apache.ode.store.jpa.DbConfStoreConnectionFactory.commitTransaction(DbConfStoreConnectionFactory.java:85)
... 6 more
Caused by: <openjpa-1.2.1-r752877:753278 nonfatal general error> org.apache.openjpa.persistence.PersistenceException: Cannot change transaction isolation level in the middle of a transaction
at org.apache.openjpa.jdbc.sql.DBDictionary.narrow(DBDictionary.java:4232)
at org.apache.openjpa.jdbc.sql.DBDictionary.newStoreException(DBDictionary.java:4197)
at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:102)
at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:88)
at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:64)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.connect(JDBCStoreManager.java:930)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.retainConnection(JDBCStoreManager.java:216)
at org.apache.openjpa.kernel.DelegatingStoreManager.retainConnection(DelegatingStoreManager.java:163)
at org.apache.openjpa.kernel.BrokerImpl.retainConnection(BrokerImpl.java:3710)
at org.apache.openjpa.kernel.BrokerImpl.beginStoreManagerTransaction(BrokerImpl.java:1283)
at org.apache.openjpa.kernel.BrokerImpl.flush(BrokerImpl.java:1968)
at org.apache.openjpa.kernel.BrokerImpl.flushSafe(BrokerImpl.java:1908)
at org.apache.openjpa.kernel.BrokerImpl.beforeCompletion(BrokerImpl.java:1826)
at bitronix.tm.BitronixTransaction.fireBeforeCompletionEvent(BitronixTransaction.java:532)
at bitronix.tm.BitronixTransaction.commit(BitronixTransaction.java:235)
... 8 more
Caused by: org.postgresql.util.PSQLException: Cannot change transaction isolation level in the middle of a transaction
at org.postgresql.jdbc2.AbstractJdbc2Connection.setTransactionIsolation(AbstractJdbc2Connection.java:944)
at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at bitronix.tm.resource.jdbc.BaseProxyHandlerClass.invoke(BaseProxyHandlerClass.java:64)
at $Proxy5.setTransactionIsolation(Unknown Source)
at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at bitronix.tm.resource.jdbc.BaseProxyHandlerClass.invoke(BaseProxyHandlerClass.java:64)
at $Proxy7.setTransactionIsolation(Unknown Source)
at org.apache.openjpa.lib.jdbc.DelegatingConnection.setTransactionIsolation(DelegatingConnection.java:257)
at org.apache.openjpa.lib.jdbc.ConfiguringConnectionDecorator.decorate(ConfiguringConnectionDecorator.java:95)
at org.apache.openjpa.lib.jdbc.DecoratingDataSource.decorate(DecoratingDataSource.java:100)
at org.apache.openjpa.lib.jdbc.DecoratingDataSource.getConnection(DecoratingDataSource.java:88)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.connectInternal(JDBCStoreManager.java:941)
at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.connect(JDBCStoreManager.java:926)
... 17 more

Regards,
Vito