Date: Tue, 6 Jun 2006 10:14:17 -0500
From: "Jim C. Nasby" <jnasby@pervasive.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Simon Riggs <simon@2ndquadrant.com>,
 Andrew Sullivan <ajs@crankycanuck.ca>,
	pgsql-performance@postgresql.org
Subject: Re: Some queries starting to hang
Message-ID: <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>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <17426.1149606369@sss.pgh.pa.us>
User-Agent: Mutt/1.5.11

On Tue, Jun 06, 2006 at 11:06:09AM -0400, Tom Lane wrote:
> > The idea I just had was: why do we need EXPLAIN ANALYZE to run to
> > completion? In severe cases like this thread, we might be able to
> > discover the root cause by a *partial* execution of the plan, as long as
> > it was properly instrumented. That way, the OP might have been able to
> > discover the root cause himself...
> 
> 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. It might even make sense to highlight
that node in the output, so that users don't have to wade through a sea
of numbers to find it.

If it is important to report how far along the query got, it seems that
could always be added to the explain output.
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461