| From: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, Zeugswetter Andreas DCP SD <ZeugswetterA(at)spardat(dot)at>, Greg Stark <gsstark(at)mit(dot)edu>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Rod Taylor <pg(at)rbt(dot)ca>, "Bort, Paul" <pbort(at)tmwsystems(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Compression and on-disk sorting |
| Date: | 2006-05-26 21:04:26 |
| Message-ID: | 20060526210426.GR59464@pervasive.com |
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| Lists: | pgsql-hackers |
On Fri, May 26, 2006 at 04:41:51PM -0400, Tom Lane wrote:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > There is a noticeable rise in sort time with increasing work_mem, but
> > that needs to be offset from the benefit that in-general comes from
> > using a large Heap for the sort. With the data you're using that always
> > looks like a loss, but that isn't true with all input data orderings.
>
> Yeah, these are all the exact same test data, right? We need a bit more
> variety in the test cases before drawing any sweeping conclusions.
All testing is select count(*) from (select * from accounts order by
bid) a; hitting a pgbench database, since that's something anyone can
(presumably) reproduce. Suggestions for other datasets welcome.
--
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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