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Re: [Glue] Deadlock bug

Josh Berkus <josh@agliodbs.com>

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From: Josh Berkus <josh@agliodbs.com>
To: glue@pgexperts.com
Cc: Joel Jacobson <joel@gluefinance.com>, Magnus Hagander <magnus@hagander.net>, pgsql-hackers@postgresql.org
Date: 2010-08-20T18:28:50Z
Lists: pgsql-hackers 
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