Received: from localhost (unknown [200.46.204.187])
	by postgresql.org (Postfix) with ESMTP id 296BA2E3DDA
	for <pgsql-performance-postgresql.org@postgresql.org>;
	Wed, 19 Dec 2007 13:14:27 -0400 (AST)
Received: from postgresql.org ([200.46.204.71])
	by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024)
	with ESMTP id 17927-05 for
	<pgsql-performance-postgresql.org@postgresql.org>;
	Wed, 19 Dec 2007 13:14:15 -0400 (AST)
Received: from wizmail.org (wizmail.org [217.146.104.199])
	by postgresql.org (Postfix) with ESMTP id 84F5A2E3DC2
	for <pgsql-performance@postgresql.org>;
	Wed, 19 Dec 2007 13:14:21 -0400 (AST)
Received: from mail.vmetro.co.uk ([217.205.232.226] helo=[192.9.200.97])
	(from_AS 4589) by wizmail.org with esmtpsa
	(TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.67) id 1J52Uu-00018x-5d
	(return-path <jgh@wizmail.org>); Wed, 19 Dec 2007 17:14:20 +0000
Message-ID: <476950E8.50009@wizmail.org>
Date: Wed, 19 Dec 2007 17:12:08 +0000
From: Jeremy Harris <jgh@wizmail.org>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US;
	rv:1.8.1.6) Gecko/20070728 Thunderbird/2.0.0.6 Mnenhy/0.7.5.666
MIME-Version: 1.0
To: pgsql-performance@postgresql.org
Subject: Re: Optimising a query
References: <4768B4D1.1090702@reynolds.com.au>
In-Reply-To: <4768B4D1.1090702@reynolds.com.au>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Archive-Number: 200712/284
X-Sequence-Number: 28100

Paul Lambert wrote:
> "                                            ->  Merge Join 
> (cost=35.56..19732.91 rows=12 width=48) (actual time=0.841..2309.828 
> rows=206748 loops=1)"

I'm no expert, but in the interests of learning: why is the
rows estimate so far out for this join?

Thanks,
    Jeremy