Skip site navigation (1) Skip section navigation (2)

Re: App very unresponsive while performing simple update

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Greg Stark <gsstark(at)mit(dot)edu>
Cc: 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 21:32:19
Message-ID: 159.1148851939@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Greg Stark <gsstark(at)mit(dot)edu> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>> 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.

Yeah, but it was a ShareLock on a transaction ID, which is the trace
of something doing XactLockTableWait, which is only done if we're
blocking on a locked or updated-but-uncommitted row.

Since Brendan says he's using 8.1, the FK theory is out, and I think
what this probably is is a garden-variety deadlock on tuple updates, ie,
two concurrent transactions tried to update the same tuples in different
orders.

			regards, tom lane

In response to

Responses

pgsql-performance by date

Next:From: Erwin BrandstetterDate: 2006-05-28 21:56:27
Subject: Re: Query performance
Previous:From: Brendan DuddridgeDate: 2006-05-28 19:17:07
Subject: Re: App very unresponsive while performing simple update

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group