Could someone please explain to me what the new method Session.saveOrUpdateCopy(Object) does? I read the javadoc, but I don't understand what the real difference to Session.saveOrUpdate(Object) is and where this would be useful.

Thanks!

The difference is that saveOrUpdateCopy will not attach the passed entity to the session in the case of update. Instead it will load the corresponding entity from the database and copy the values from the passed entity to the persistent one. The persistent instance is then returned.

Thanks. Would you happen to know an example where this would be useful?

Ummmmm, not off the top of my head :)

Maybe if it came from a different, still open session (like from another session factory)

We don't think its useful and don't recommend it. It is there for the sake of completeness, since we now aim to be a "complete" ORM solution.

It *does* let you avoid the dreaded NonUniqueObjectException, but at the cost of performance.

(Actually NonUniqueObjectException is your friend. It tells you that you are risking possible loss of some changes, so in this sense saveOrUpdateCopy() is less "safe".)

It may also be used as an alternative to select-before-update if you are trying to avoid unnecessary SQL UPDATEs due to lack of a snapshot.