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

From: Andres Freund
Subject: Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
Date: ,
Msg-id: 200912291213.21721.andres@anarazel.de
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In response to: Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Stark)
List: pgsql-performance

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8.4.1 ubuntu karmic slow createdb  (Michael Clemmons, )
 Re: 8.4.1 ubuntu karmic slow createdb  (Andres Freund, )
  Re: 8.4.1 ubuntu karmic slow createdb  (Michael Clemmons, )
   Re: 8.4.1 ubuntu karmic slow createdb  (Andres Freund, )
    Re: 8.4.1 ubuntu karmic slow createdb  (Nikolas Everett, )
     Re: 8.4.1 ubuntu karmic slow createdb  ("Joshua D. Drake", )
      Re: 8.4.1 ubuntu karmic slow createdb  (Nikolas Everett, )
       Re: 8.4.1 ubuntu karmic slow createdb  ("Joshua D. Drake", )
        Re: 8.4.1 ubuntu karmic slow createdb  (Nikolas Everett, )
         Re: 8.4.1 ubuntu karmic slow createdb  (Scott Marlowe, )
          Re: 8.4.1 ubuntu karmic slow createdb  (Scott Carey, )
           Re: 8.4.1 ubuntu karmic slow createdb  (Scott Marlowe, )
         Re: 8.4.1 ubuntu karmic slow createdb  (Scott Mead, )
          Re: 8.4.1 ubuntu karmic slow createdb  (Scott Marlowe, )
           Re: 8.4.1 ubuntu karmic slow createdb  (Robert Haas, )
          Re: 8.4.1 ubuntu karmic slow createdb  (Greg Smith, )
           Re: 8.4.1 ubuntu karmic slow createdb  (Michael Clemmons, )
            Re: 8.4.1 ubuntu karmic slow createdb  (Scott Marlowe, )
             Re: 8.4.1 ubuntu karmic slow createdb  (Andres Freund, )
            Re: 8.4.1 ubuntu karmic slow createdb  (Michael Clemmons, )
             Re: 8.4.1 ubuntu karmic slow createdb  (Andres Freund, )
              Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
               Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                 Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Stark, )
                  Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Stark, )
                   Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Stark, )
                    Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                    Re: Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Smith, )
                    Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Smith, )
                   Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                   Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Tom Lane, )
                    Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Stark, )
                     Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Tom Lane, )
                      Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Robert Haas, )
                       Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                        Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Robert Haas, )
                         Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                         Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Tom Lane, )
                          Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Robert Haas, )
                           Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Stark, )
                            Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                            Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Robert Haas, )
                             Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                              Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Smith, )
                               Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                                Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Robert Haas, )
                                 Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Smith, )
                                  Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Tom Lane, )
                                   Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Robert Haas, )
                                    Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                                     Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                                      Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Alvaro Herrera, )
                                       Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Robert Haas, )
                                        Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                                        Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Stark, )
                                         Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                                        Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                     Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                     Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Robert Haas, )
                   Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                  Re: Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
               Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Tom Lane, )
                Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                 Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Smith, )
                  Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                   Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Michael Clemmons, )
                    Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                     Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Michael Clemmons, )
                      Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                   Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Stark, )
                    Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
               Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Greg Stark, )
                Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (Andres Freund, )
                Re: [PERFORM] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1ubuntu karmic slow createdb)  (Andres Freund, )
                 Re: Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (, )
                Re: Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)  (, )
            Re: 8.4.1 ubuntu karmic slow createdb  (Thomas Kellerer, )
       Re: 8.4.1 ubuntu karmic slow createdb  ("Joshua D. Drake", )
     Re: 8.4.1 ubuntu karmic slow createdb  ("Joshua D. Drake", )

On Tuesday 29 December 2009 11:48:10 Greg Stark wrote:
> On Tue, Dec 29, 2009 at 2:05 AM, Andres Freund <> wrote:
> >  Reads Completed:        2,        8KiB  Writes Completed:     2362,
> >  29672KiB New:
> >  Reads Completed:        0,        0KiB  Writes Completed:      550,
> > 5960KiB
>
> It looks like the new method is only doing 1/6th as much i/o. Do you
> know what's going on there?
While I was surprised by the amount of difference I am not surprised at all
that there is a significant one - currently the fsync will write out a whole
bunch of useless stuff every time its called (all metadata, directory structure
and so on)

This is reproducible...

6MB sounds sensible for the operation btw - the template database is around
5MB.


Will try to analyze later what exactly causes the additional io.


Andres


pgsql-performance by date:

From: Andres Freund
Date:
Subject: Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
From: Andres Freund
Date:
Subject: Re: [HACKERS] Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)