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Date: Tue, 9 Aug 2005 12:52:01 -0600
From: Michael Fuhr <mike@fuhr.org>
To: Dan Harris <fbsd@drivefaster.net>
Cc: pgsql-performance@postgresql.org
Subject: Re: Table locking problems?
Message-ID: <20050809185201.GA25325@winnie.fuhr.org>
References: <52CFA236-FC43-4018-B399-1854240110FF@drivefaster.net>
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On Tue, Aug 09, 2005 at 12:04:11PM -0600, Dan Harris wrote:
> These changes have definitely improved performance, but I am now  
> finding some trouble with UPDATE or DELETE queries "hanging" and  
> never releasing their locks.  As this happens, other statements queue  
> up behind it.

Have you examined pg_locks to see if the UPDATE or DELETE is blocked
because of a lock another session holds?

Are you using foreign keys?  When updating referencing rows, released
versions of PostgreSQL acquire a lock on the referenced row that can
hurt concurrency or cause deadlock (this will be improved in 8.1).

-- 
Michael Fuhr