i'm getting a Load Failed exception when i try to load an abstract entity with the EntityManager's find method.

It has something to do with the UNION (see last line of exception) query hibernate probably executes to have all the classes in the class hierarchy (i use TABLE_PER_CLASS)

anyone knows a solution to this problem?

17:26:58,203 INFO [DefaultLoadEventListener] Error performing load command
org.hibernate.exception.SQLGrammarException: could not load an entity: [be.acme.entities.document.AbstractDocument#18267]
 at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:67)
 at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
 at org.hibernate.loader.Loader.loadEntity(Loader.java:1799)
 at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:48)
 at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:42)
 at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:2821)
 at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:370)
 at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:351)
 at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:122)
 at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:178)
 at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:86)
 at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:871)
 at org.hibernate.impl.SessionImpl.get(SessionImpl.java:808)
 at org.hibernate.impl.SessionImpl.get(SessionImpl.java:801)
 at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:155)
 at org.jboss.ejb3.entity.TransactionScopedEntityManager.find(TransactionScopedEntityManager.java:164)
 at be.profitplus.document.AbstractDocumentDAOBean.updateDocument(AbstractDocumentDAOBean.java:55)
 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:585)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:112)
 at org.jboss.ejb3.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:166)
 at org.jboss.ejb3.interceptor.EJB3InterceptorsInterceptor.invoke(EJB3InterceptorsInterceptor.java:63)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.entity.TransactionScopedEntityManagerInterceptor.invoke(TransactionScopedEntityManagerInterceptor.java:54)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.AllowedOperationsInterceptor.invoke(AllowedOperationsInterceptor.java:47)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:79)
 at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:197)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:76)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:62)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:78)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:47)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.stateless.StatelessContainer.dynamicInvoke(StatelessContainer.java:227)
 at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:106)
 at org.jboss.aspects.remoting.AOPRemotingInvocationHandler.invoke(AOPRemotingInvocationHandler.java:82)
 at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:828)
 at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:681)
 at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:358)
 at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:412)
 at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:239)
Caused by: java.sql.SQLException: ERROR: UNION types character varying and integer cannot be matched