I got a persistent, attached map (cascade: all, delete-orphan) on an entity. When I clear() this map and fill in new objects with the same key I get unique constraints violations on the map key when committing, because hibernate does NOT issue any sql deletes. When I manually do a Session.flush() after the Map.clear() (what I want to avoid), hibernate generates the deletes and all is fine. What have I to do to get these sql deletes without a manual flush?

From

10.10. Flushing the Session

the order in which hibernate executes pending sql senteces is:
The SQL statements are issued in the following order

1. all entity insertions, in the same order the corresponding objects were saved using Session.save()
2. all entity updates
3. all collection deletions
4. all collection element deletions, updates and insertions
5. all collection insertions
6. all entity deletions, in the same order the corresponding objects were deleted using Session.delete()

so it should work when you do the commit...

Could you try to do "map.remove()" for each object you want to delete instead of the clear() and see if it works?