Damian

It's not necessarily purely a priority thing - if both processes have equal priority, then the process that's easier to roll back is chosen as the victim.

If this is just a one-off then, to be honest, I wouldn't spend too much time on it.  Try to make sure that the job runs when as little else as possible is going on, put a retry on the bit that failed, and move on.

If you want to understand why the deadlock occurred, I find that this is an excellent resource.  It can get a bit tedious working through it, but stick with it, because it usually leads to the cause!

John