To: "Jim C. Nasby" <jnasby@pervasive.com>
cc: Simon Riggs <simon@2ndquadrant.com>,
 Andrew Sullivan <ajs@crankycanuck.ca>,
	pgsql-performance@postgresql.org
Subject: Re: Some queries starting to hang 
In-reply-to: <20060606151416.GD53487@pervasive.com> 
References: <1149534308.3583.56.camel@bg002441.pro-unlimited.com>
	<22706.1149538039@sss.pgh.pa.us>
	<20060605203851.GB7071@phlogiston.dyndns.org>
	<23915.1149541591@sss.pgh.pa.us>
	<1149604741.2621.487.camel@localhost.localdomain>
	<17148.1149605005@sss.pgh.pa.us>
	<1149605576.2621.502.camel@localhost.localdomain>
	<17426.1149606369@sss.pgh.pa.us>
	<20060606151416.GD53487@pervasive.com>
Comments: In-reply-to "Jim C. Nasby" <jnasby@pervasive.com>
	message dated "Tue, 06 Jun 2006 10:14:17 -0500"
Date: Tue, 06 Jun 2006 11:41:15 -0400
Message-ID: <17758.1149608475@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

"Jim C. Nasby" <jnasby@pervasive.com> writes:
> On Tue, Jun 06, 2006 at 11:06:09AM -0400, Tom Lane wrote:
>> I don't think that helps, as it just replaces one uncertainty by
>> another: how far did the EXPLAIN really get towards completion of the
>> plan?  You still don't have any hard data.

> Does that really matter, though? The point is to find the node where the
> estimate proved to be fantasy.

No, the point is to find out what reality is.  Just knowing that the
estimates are wrong doesn't really get you anywhere (we pretty much knew
that before we even started looking at the EXPLAIN, eh?).

			regards, tom lane