pg.ddx.io  pgsql-performance@postgresql.org mailing list archive  

help / color / mirror / Atom feed
From: PFC <lists@peufeu.com>
To: Greg Smith <gsmith@gregsmith.com>
To: Matthew Wakeling <matthew@flymine.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: I/O on select count(*)
Date: Mon, 19 May 2008 19:14:48 +0200
Message-ID: <op.ubeviyrgcigqcu@apollo13.peufeu.com> (raw)
In-Reply-To: <Pine.GSO.4.64.0805191137480.25115@westnet.com>
References: <920841.71690.qm@web44808.mail.sp1.yahoo.com>
	<482B1D5F.EE98.0025.0@wicourts.gov>
	<Pine.GSO.4.64.0805142133250.27290@westnet.com>
	<20080515020553.GN9838@alvh.no-ip.org>
	<Pine.LNX.4.64.0805151245360.16756@aragorn.flymine.org>
	<20080515155232.GC8221@alvh.no-ip.org>
	<Pine.GSO.4.64.0805161118210.4987@westnet.com>
	<20080516201528.GJ13061@alvh.no-ip.org>
	<18382.1210992302@sss.pgh.pa.us>
	<Pine.LNX.4.64.0805191257020.16756@aragorn.flymine.org>
	<Pine.GSO.4.64.0805191137480.25115@westnet.com>


> The real question in my mind is why this turns into a bottleneck before  
> the similar task of cleaning the 16MB XLOG segment does.  I expected  
> that one would need to be cracked before the CLOG switch time could  
> possibly be an issue, but reports from the field seem to suggest  
> otherwise.

	Hm, on current CPUs zeroing 8kB of RAM should take less than 2 us... now  
if it has to be written to disk, that's another story !



view thread (54+ messages)  latest in thread

Message-ID: <op.ubeviyrgcigqcu@apollo13.peufeu.com>
Permalink:  ../op.ubeviyrgcigqcu@apollo13.peufeu.com/
Also on:    postgresql.org/message-id/op.ubeviyrgcigqcu@apollo13.peufeu.com

 · 

reply
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: lists@peufeu.com, gsmith@gregsmith.com, matthew@flymine.org
  Subject: Re: I/O on select count(*)
  In-Reply-To: <op.ubeviyrgcigqcu@apollo13.peufeu.com>

* 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