Date: Thu, 11 May 2006 17:58:42 -0500
From: "Jim C. Nasby" <jnasby@pervasive.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Zeugswetter Andreas DCP SD <ZeugswetterA@spardat.at>,
	PFC <lists@peufeu.com>, Greg Stark <gsstark@mit.edu>,
	pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] Big IN() clauses etc : feature proposal
Message-ID: <20060511225842.GZ99570@pervasive.com>
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	<20060511210141.GP99570@pervasive.com>
	<4335.1147385316@sss.pgh.pa.us>
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On Thu, May 11, 2006 at 06:08:36PM -0400, Tom Lane wrote:
> "Jim C. Nasby" <jnasby@pervasive.com> writes:
> > I'd hope that wasn't what's happening... is the backend smart enough to
> > know not to fsync anything involved with the temp table?
> 
> The catalog entries required for it have to be fsync'd, unless you enjoy
> putting your entire database at risk (a bad block in pg_class, say,
> would probably take out more than one table).

Yeah, thought about that after sending... :(

> It's interesting to speculate about keeping such catalog entries in
> child tables of pg_class etc that are themselves temp tables.  Resolving
> the apparent circularity of this is left as an exercise for the reader.

Well, since it'd be a system table with a fixed OID there could
presumably be a special case in the recovery code for it, though that's
pretty fugly sounding.

Another alternative would be to support global temp tables... I think
that would handle all the complaints of the OP except for the cost of
analyze. I suspect this would be easier to do than creating a special
type of temp table that used tuplestore instead of the full table
framework, and it'd certainly be more general-purpose.
-- 
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