From: Tom Lane <tgl@sss.pgh.pa.us>
To: Hilary Forbes <hforbes@dmr.co.uk>
Cc: pgsql-performance@postgresql.org
Subject: Re: Slow update
Date: Mon, 12 Sep 2005 10:07:26 -0400
Message-ID: <21152.1126534046@sss.pgh.pa.us> (raw)
In-Reply-To: <5.1.0.14.0.20050912100150.01f47f18@mailserver.dmr.co.uk>
References: <5.1.0.14.0.20050912100150.01f47f18@mailserver.dmr.co.uk>
Hilary Forbes <hforbes@dmr.co.uk> writes:
> I need to set the value of a field in table A to a value in table B depending on the existence of the record in table B. So what I have done is
> UPDATE tableA set a.val1=b.somefield FROM tableA a, tableB b WHERE a.key1=b.key1;
You've written an unconstrained join to a second copy of tableA.
regards, tom lane
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, hforbes@dmr.co.uk
Subject: Re: Slow update
In-Reply-To: <21152.1126534046@sss.pgh.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox