From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Martijn van Oosterhout <kleptog@svana.org>
Cc: Ron Peacetree <rjpeace@earthlink.net>
Cc: Jonah H. Harris <jonah.harris@gmail.com>
Cc: pgsql-hackers@postgresql.org
Cc: pgsql-performance@postgresql.org
Subject: Re: [HACKERS] A Better External Sort?
Date: Thu, 6 Oct 2005 16:17:21 -0400
Message-ID: <20051006201721.GB6513@surnet.cl> (raw)
In-Reply-To: <25130.1128628658@sss.pgh.pa.us>
References: <138872.1128556455518.JavaMail.root@elwamui-milano.atl.sa.earthlink.net>
<20051006165725.GF10127@svana.org>
<25130.1128628658@sss.pgh.pa.us>
On Thu, Oct 06, 2005 at 03:57:38PM -0400, Tom Lane wrote:
> Martijn van Oosterhout <kleptog@svana.org> writes:
> > Indeed, one of the things on my list is to remove all the lseeks in
> > favour of pread. Halving the number of kernel calls has got to be worth
> > something right? Portability is an issue ofcourse...
>
> Being sure that it's not a pessimization is another issue. I note that
> glibc will emulate these functions if the kernel doesn't have them;
> which means you could be replacing one kernel call with three.
>
> And I don't think autoconf has any way to determine whether a libc
> function represents a native kernel call or not ...
The problem kernels would be Linux 2.0, which I very much doubt is going
to be present in to-be-deployed database servers.
Unless someone runs glibc on top of some other kernel, I guess. Is this
a common scenario? I've never seen it.
--
Alvaro Herrera http://www.amazon.com/gp/registry/DXLWNGRJD34
Oh, oh, las chicas galacianas, lo harán por las perlas,
¡Y las de Arrakis por el agua! Pero si buscas damas
Que se consuman como llamas, ¡Prueba una hija de Caladan! (Gurney Halleck)
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To: pgsql-performance@postgresql.org
Cc: alvherre@alvh.no-ip.org, tgl@sss.pgh.pa.us, kleptog@svana.org, rjpeace@earthlink.net, jonah.harris@gmail.com, pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] A Better External Sort?
In-Reply-To: <20051006201721.GB6513@surnet.cl>
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