You might want to look into advisory locking. If your locks don't need
to be longer than the life of an active EntityManager session then you
can probably just issue a native query through the EntityManager to
acquire the lock before doing anything more.
Thank you very much for this and the link. (I'm much more an OOP programmer than a DB programmer.) Too bad about the non-portability, but I suppose it had to be.
I am a little bemused that the only supported Java persistence strategy is to try the operation, and then react to failure by recreating the entire transaction. At first I assumed I could catch the exception and then re-do the one table operation that had failed...nope, not in a transaction any more.
