This is cross-posted from the JBoss Persistence forum. I apologize if this is un-cool - I wasn't sure how the two are related, and no one on that forum seemed to have an answer.

I have some entities that are in many-to-many, bidirectional relationships with very large numbers of other entities (millions). Deleting one of them the naive way (walking through all the related entities and remove()-ing it from their collections) is not feasible, so I used a native SQL query to remove all references from the join table. This almost works fine. Unfortunately, some small number of those millions of related entities are usually being managed, but I don't know which ones. If I knew which they were, I could call refresh() on each.

Is there some way of finding out which entities of a given type are currently being managed? Is there some better way of accomplishing this delete?

Thanks,

Joe

Isn't entity.getCollection().clear(); fast enough? I think Hibernate implement that in a smart way

The one-shot delete with collection.clear() only works for collections of value types. The solution is not to map the many-to-many association but only the foreign keys to many-to-one.

Thanks for the replies! I'm not sure I understand your recommendations, though. My classes look something like this:



The persons collection in Group has millions of entries. When I delete a Group, any Persons currently being managed may have that Group in their groups collection. I don't want to walk through all of them, and I don't know how to find those few.

Perhaps I just misunderstand how Hibernate works? I was under the impression that Hibernate won't clean up the other side of my relationships if I just use group.getPersons().clear(). Is that not correct?
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you're correct, but you haven't told me that before ;-)