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Re: Scrollable cursors and Sort performance

From: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Scrollable cursors and Sort performance
Date: 2006-02-27 22:55:31
Message-ID: 20060227225531.GP82012@pervasive.com (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
On Mon, Feb 27, 2006 at 02:17:23PM +0000, Simon Riggs wrote:
> > Interesting point: how should EXPLAIN ANALYZE set these bits?  For its
> > own purposes it need not request random access, but it might be
> > interesting to make it possible to examine both the random and nonrandom
> > behaviors, now that these will be significantly different performancewise.
> > Possibly we could make EXPLAIN ANALYZE EXECUTE set the random-access
> > bits.
> 
> Good point. Whichever we do will be wrong in some cases.... I've no real
> opinion on this other than a vague preference for it to be quick.

Wouldn't an EXPLAIN ANALYZE DECLARE ... have the right information to
know if backward scan, etc was needed?
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby(at)pervasive(dot)com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

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