Avoiding deadlocks ...

Kevin,

This one is for you:

Two sessions, in transaction:

Process A		Process B

update session where id = X;		update order where orderid = 5;
update order where orderid = 5;		update order where orderid = 5;
... deadlock error.

It seems like we ought to be able to avoid a deadlock in this case;
there's a clear precedence of who grabbed the order row first.  Does
your serializability patch address the above situation at all?

--                                  -- Josh Berkus                                    PostgreSQL Experts Inc.                                    http://www.pgexperts.com