Brett Meyer commented on an issue
Hibernate ORM / Bug HHH-8557
Transactional problem with database constraint violation when persist more than one entity
We do this in one EJB transaction (REQUIERES_NEW),is to say, in one java method with transaction Requeries_NEW:

- Create object1
- em.persist(ob1)
-Create object2
- em.persist(ob2)

When the container flush the transaction, we've a database constraint violation over ob2. But when we go to database we see that ob1 is persisted.