From: | Curt Sampson <cjs(at)cynic(dot)net> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Non-linear Performance |
Date: | 2002-05-31 16:10:13 |
Message-ID: | Pine.NEB.4.43.0206010057260.657-100000@angelic.cynic.net |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
On Fri, 31 May 2002, Tom Lane wrote:
> On a pure random-chance basis, you'd not expect that fetching 5k rows
> out of 100m would hit the same table block twice --- but I'm wondering
> if the data was somewhat clustered.
I dont' think so. I generated the data myself, and the data are
entirely pseudo-random. (Unless perl's PNRG is quite screwed,
which doesn't seem so likely.)
> Do the system usage stats on your machine reflect the difference
> between physical reads and reads satisfied from kernel buffer cache?
Well, not that I've been looking at yet, but it would definitely
be cool if I could figure out a way to do this.
> Or maybe your idea about extra seek time is correct.
If I can get a spare couple of hours, I'll cons up a little benchmark
program to help determine seek time on disks and various parts of
disks, and play a bit.
But on the other hand, it's not like I can do all that much about this
sort of problem, anyway, and I'm kind of doubting that the fault here
lies with postgres.
cjs
--
Curt Sampson <cjs(at)cynic(dot)net> +81 90 7737 2974 http://www.netbsd.org
Don't you know, in this new Dark Age, we're all light. --XTC
From | Date | Subject | |
---|---|---|---|
Next Message | Devrim GUNDUZ | 2002-05-31 16:15:19 | Re: Row Limit on tables |
Previous Message | Scott Marlowe | 2002-05-31 15:56:57 | Re: www.postgresql.org search not working |