Skip site navigation (1) Skip section navigation (2)

Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)

From: Andres Freund <andres(at)anarazel(dot)de>
To: pgsql-hackers(at)postgresql(dot)org
Cc: pgsql-performance(at)postgresql(dot)org, Michael Clemmons <glassresistor(at)gmail(dot)com>, Hannu Krosing <hannu(at)2ndquadrant(dot)com>, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
Subject: Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
Date: 2009-12-28 22:59:43
Message-ID: 200912282359.43979.andres@anarazel.de (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-performance
On Monday 28 December 2009 23:54:51 Andres Freund wrote:
> On Saturday 12 December 2009 21:38:41 Andres Freund wrote:
> > On Saturday 12 December 2009 21:36:27 Michael Clemmons wrote:
> > > If ppl think its worth it I'll create a ticket
> >
> > Thanks, no need. I will post a patch tomorrow or so.
> 
> Well. It was a long day...
> 
> Anyway.
> In this patch I delay the fsync done in copy_file and simply do a second
>  pass over the directory in copy_dir and fsync everything in that pass.
> Including the directory - which was not done before and actually might be
> necessary in some cases.
> I added a posix_fadvise(..., FADV_DONTNEED) to make it more likely that the
> copied file reaches storage before the fsync. Without the speed benefits
>  were quite a bit smaller and essentially random (which seems sensible).
> 
> This speeds up CREATE DATABASE from ~9 seconds to something around 0.8s on
>  my laptop.  Still slower than with fsync off (~0.25) but quite a worthy
>  improvement.
> 
> The benefits are obviously bigger if the template database includes
>  anything added.
Obviously the patch would be helpfull.

Andres

Attachment: 0001-Delay-fsyncing-files-during-copying-in-CREATE-DATABA.patch
Description: text/x-patch (3.2 KB)

In response to

Responses

pgsql-performance by date

Next:From: Tom LaneDate: 2009-12-28 23:06:28
Subject: Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
Previous:From: Andres FreundDate: 2009-12-28 22:54:51
Subject: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)

pgsql-hackers by date

Next:From: Guillaume LelargeDate: 2009-12-28 23:03:45
Subject: Re: Application name patch - v3
Previous:From: Dimitri FontaineDate: 2009-12-28 22:58:36
Subject: Re: Admission Control Policy

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group