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Re: [PERFORM] Help with tuning this query (with

From: "Steinar H(dot) Gunderson" <sgunderson(at)bigfoot(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Dave Held <dave(dot)held(at)arrayservicesgrp(dot)com>,Greg Stark <gsstark(at)mit(dot)edu>, John A Meinel <john(at)arbash-meinel(dot)com>,Magnus Hagander <mha(at)sollentuna(dot)net>,Ken Egervari <ken(at)upfactor(dot)com>, pgsql-performance(at)postgresql(dot)org,pgsql-hackers-win32(at)postgresql(dot)org
Subject: Re: [PERFORM] Help with tuning this query (with
Date: 2005-03-08 02:06:24
Message-ID: 20050308020624.GA753@uio.no (view raw or flat)
Thread:
Lists: pgsql-hackers-win32pgsql-performance
On Mon, Mar 07, 2005 at 09:02:38PM -0500, Tom Lane wrote:
> One thought that was bothering me was that if the CPU goes idle while
> waiting for disk I/O, its clock might stop or slow down dramatically.
> If we believed such a counter for EXPLAIN, we'd severely understate
> the cost of disk I/O.
> 
> I dunno if that is the case on any Windows hardware or not, but none
> of this thread is making me feel confident that we know what
> QueryPerformanceCounter does measure.

I believe the counter is actually good in such a situation -- I'm not a Win32
guru, but I believe it is by far the best timer for measuring, well,
performance of a process like this. After all, it's what it was designed to
be :-)

OBTW, I think I can name something like 15 or 20 different function calls to
measure time in the Win32 API (all of them in use); it really is a giant
mess.

/* Steinar */
-- 
Homepage: http://www.sesse.net/

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