Hi, From Java EE tutorial, i was read that the joined subclass strategies could have a poor performance for extensive class hierarchies because need some joins to get the rows of the database. I am developing an application that use three levels of entity inheritance and i would use this strategy for mapping my entities to my database schema, but is my first time that i do it and i don't know that three levels of inheritance could have poor performance. From the point of view of yours experience, is a high level of inheritance (three class, main entity, another that extend it, and another extend) for use this strategy? what do you think that is the top level of inheritance for use joined subclass strategy for mapping my entities class?? thank and sorry for my poor english