Date: Tue, 6 Sep 2005 16:43:15 +0100
From: Matthew Sackman <matthew@lshift.net>
To: pgsql-performance@postgresql.org
Subject: Re: Poor performance of delete by primary key
Message-ID: <20050906154315.GL382@pongo.lshift.net>
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	<18162.1126020720@sss.pgh.pa.us>
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On Tue, Sep 06, 2005 at 11:32:00AM -0400, Tom Lane wrote:
> "Brian Choate" <brianc@nimblefish.com> writes:
> > We are seeing a very strange behavior from postgres. For one of our very =
> > common tasks we have to delete records from a table of around 500,000 =
> > rows. The delete is by id which is the primary key. It seems to be =
> > consistently taking around 10 minutes to preform. This is totally out of =
> > line with the rest of the performance of the database.
> 
> I'll bet this table has foreign-key references from elsewhere, and the
> referencing columns are either not indexed, or not of the same datatype
> as the master column.

Wouldn't setting the FK as deferrable and initially deferred help here
too as then the FK wouldn't be checked until the transaction ended?

Matthew