I am trying to develop a entity which extends another entity and which use the annotation @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS), but this only provides an exception as the sub class does not have an @Id annotated: org.hibernate.MappingException: Cannot use identity column key generation with <union-subclass> mapping for: concept.entity.Entity However: If I do annotate this @Id, I get this one: org.hibernate.AnnotationException: Unable to define/override @Id(s) on a subclass: concept.entity.Entity Suggestions? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3959817#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...