From: Tom Lane <tgl@sss.pgh.pa.us>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: Stephan Szabo <sszabo@megazone.bigpanda.com>
Cc: Karim A Nassar <Karim.Nassar@NAU.EDU>
Cc: Christopher Kings-Lynne <chriskl@familyhealth.com.au>
Cc: pgsql-performance@postgresql.org
Subject: Re: Delete query takes exorbitant amount of time
Date: Tue, 29 Mar 2005 10:31:50 -0500
Message-ID: <22527.1112110310@sss.pgh.pa.us> (raw)
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Simon Riggs <simon@2ndquadrant.com> writes:
> If action is NO ACTION or RESTRICT then
> we need to SELECT at most 1 row that matches the criteria
> which means we can use LIMIT 1
> If action is CASCADE, SET NULL, SET DEFAULT then
> we need to UPDATE or DELETE all rows that match the criteria
> which means we musnt use LIMIT and need to use FOR UPDATE
Huh? UPDATE/DELETE don't use FOR UPDATE. I think you have failed
to break down the cases sufficiently. In particular it matters which
side of the RI constraint you are working from ...
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, simon@2ndquadrant.com, sszabo@megazone.bigpanda.com, Karim.Nassar@NAU.EDU, chriskl@familyhealth.com.au
Subject: Re: Delete query takes exorbitant amount of time
In-Reply-To: <22527.1112110310@sss.pgh.pa.us>
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