To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Greg Stark <gsstark@mit.edu>, Brendan Duddridge <brendan@clickspace.com>,
	PostgreSQL Performance <pgsql-performance@postgresql.org>
Subject: Re: App very unresponsive while performing simple update
References: <961F6F02-4B00-494C-B071-6DF76A305C14@clickspace.com>
	<21B15664-F4EE-462C-88B4-EEEB2B4A979F@clickspace.com>
	<874pzanvk6.fsf@stark.xeocode.com> <17733.1148832292@sss.pgh.pa.us>
In-Reply-To: <17733.1148832292@sss.pgh.pa.us>
From: Greg Stark <gsstark@mit.edu>
Organization: The Emacs Conspiracy; member since 1992
Date: 28 May 2006 13:55:54 -0400
Message-ID: <87slmum3th.fsf@stark.xeocode.com>
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Tom Lane <tgl@sss.pgh.pa.us> writes:

> Greg Stark <gsstark@mit.edu> writes:
> > What queries are those two processes executing? And what foreign keys do you
> > have on the product table or elsewhere referring to the product table? And
> > what indexes do you have on those columns?
> 
> And what PG version is this?  Alvaro fixed the
> foreign-keys-take-exclusive-locks problem in 8.1 ...

Except I don't think this is taking an exclusive lock at all. The original
post had the deadlock detection fire on a SharedLock. I think the other
process is also an update and is holding an exclusive lock while also
trying to acquire a SharedLock for a foreign key column.

-- 
greg