On 8/20/10 7:18 AM, Tom Lane wrote:
> It does go through without any deadlock, *if* there is no foreign key
> involved. You didn't tell us exactly what the FK relationship is, but
> I suspect the reason for the deadlock is that one process is trying to
> update a row that references some row already updated by the other.
> That will require a row-level share lock on the referenced row, so you
> can get a deadlock.
That's correct. This is the generic example I was talking about earlier
on -hackers. I'm not certain it's a bug per spec; I wanted to talk
through with Kevin what we *should* be doing in this situation.
This is one example of a set of user-hostile FK-related deadlock
behavior we have. I'm just not certain it's logically possible to
improve it.
-- -- Josh Berkus PostgreSQL Experts Inc.
http://www.pgexperts.com
