From: Martijn van Oosterhout <kleptog@svana.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
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: [PERFORM] A Better External Sort?
Date: Thu, 6 Oct 2005 23:40:17 +0200
Message-ID: <20051006214017.GH10127@svana.org> (raw)
In-Reply-To: <25400.1128630311@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>
<20051006201447.GG10127@svana.org>
<25400.1128630311@sss.pgh.pa.us>
On Thu, Oct 06, 2005 at 04:25:11PM -0400, Tom Lane wrote:
> Martijn van Oosterhout <kleptog@svana.org> writes:
> > Are we awfully worried about people still using 2.0 kernels? And it
> > would replace two calls with three in the worst case, we currently
> > lseek before every read.
>
> That's utterly false.
Oops, you're right. I usually strace during a vacuum or a large query
and my screen fills up with:
lseek()
read()
lseek()
read()
...
So didn't wonder if the straight sequential read was optimised. Still,
I think pread() would be a worthwhile improvement, at least for Linux.
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: kleptog@svana.org, tgl@sss.pgh.pa.us, rjpeace@earthlink.net, jonah.harris@gmail.com, pgsql-hackers@postgresql.org
Subject: Re: [PERFORM] A Better External Sort?
In-Reply-To: <20051006214017.GH10127@svana.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox