Re: App very unresponsive while performing simple update

From: Greg Stark <gsstark(at)mit(dot)edu>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Greg Stark <gsstark(at)mit(dot)edu>, Brendan Duddridge <brendan(at)clickspace(dot)com>, PostgreSQL Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: App very unresponsive while performing simple update
Date: 2006-05-28 17:55:54
Message-ID: 87slmum3th.fsf@stark.xeocode.com
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Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> Greg Stark <gsstark(at)mit(dot)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

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