Re: Any better plan for this query?..

From: Alvaro Herrera
Subject: Re: Any better plan for this query?..
Date: ,
Msg-id: 20090507152632.GD3026@alvh.no-ip.org
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In response to: Re: Any better plan for this query?..  (Dimitri)
List: pgsql-performance

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Any better plan for this query?..  (Dimitri, )
 Re: Any better plan for this query?..  (Craig Ringer, )
  Re: Any better plan for this query?..  (Dimitri, )
   Re: Any better plan for this query?..  (Chris, )
    Re: Any better plan for this query?..  (Dimitri, )
     Re: Any better plan for this query?..  (Richard Huxton, )
     Re: Any better plan for this query?..  (Craig Ringer, )
      Re: Any better plan for this query?..  (Kenneth Marshall, )
       Re: Any better plan for this query?..  (Matthew Wakeling, )
      Re: Any better plan for this query?..  (Dimitri, )
  Re: Any better plan for this query?..  (Kenneth Marshall, )
 Re: Any better plan for this query?..  (Heikki Linnakangas, )
  Re: Any better plan for this query?..  (Dimitri, )
   Re: Any better plan for this query?..  (Simon Riggs, )
    Re: Any better plan for this query?..  (Dimitri, )
     Re: Any better plan for this query?..  (Merlin Moncure, )
      Re: Any better plan for this query?..  (Dimitri, )
       Re: Any better plan for this query?..  (Simon Riggs, )
        Re: Any better plan for this query?..  (Dimitri, )
         Re: Any better plan for this query?..  (Tom Lane, )
          Re: Any better plan for this query?..  (Dimitri, )
          Re: Any better plan for this query?..  (Simon Riggs, )
         Re: Any better plan for this query?..  (Merlin Moncure, )
         Re: Any better plan for this query?..  (Simon Riggs, )
          Re: Any better plan for this query?..  (Dimitri, )
         Re: Any better plan for this query?..  (Aidan Van Dyk, )
          Re: Any better plan for this query?..  (Dimitri, )
           Re: Any better plan for this query?..  (Alvaro Herrera, )
            Re: Any better plan for this query?..  (Dimitri, )
             Re: Any better plan for this query?..  (Dimitri Fontaine, )
              Re: Any better plan for this query?..  (Dimitri, )
               Re: Any better plan for this query?..  (Simon Riggs, )
                Re: Any better plan for this query?..  (Dimitri, )
                 Re: Any better plan for this query?..  (Simon Riggs, )
               Re: Any better plan for this query?..  (Heikki Linnakangas, )
                Re: Any better plan for this query?..  (Dimitri, )
                 Re: Any better plan for this query?..  (Simon Riggs, )
                  Re: Any better plan for this query?..  (Dimitri, )
                   Re: Any better plan for this query?..  (Simon Riggs, )
                    Re: Any better plan for this query?..  (Dimitri, )
                     Re: Any better plan for this query?..  (Simon Riggs, )
                      Re: Any better plan for this query?..  ("Dave Dutcher", )
                       Re: Any better plan for this query?..  (Dimitri, )
                        Re: Any better plan for this query?..  (Merlin Moncure, )
                         Re: Any better plan for this query?..  (Dimitri, )
                          Re: Any better plan for this query?..  (Merlin Moncure, )
                           Re: Any better plan for this query?..  (Dimitri, )
                            Re: Any better plan for this query?..  (Merlin Moncure, )
                      Re: Any better plan for this query?..  (Dimitri, )
                       Re: Any better plan for this query?..  (Simon Riggs, )
                        Re: Any better plan for this query?..  (Dimitri, )
                         Re: Any better plan for this query?..  (Dimitri, )
                          Re: Any better plan for this query?..  (Simon Riggs, )
                           Re: Any better plan for this query?..  (Dimitri, )
                      Re: Any better plan for this query?..  (Tom Lane, )
                       Re: Any better plan for this query?..  (Dimitri, )
                       Re: Any better plan for this query?..  (Simon Riggs, )
                        Re: Any better plan for this query?..  (Matthew Wakeling, )
                         Re: Any better plan for this query?..  (Simon Riggs, )
                          Re: Any better plan for this query?..  (Simon Riggs, )
                          Re: Any better plan for this query?..  (Matthew Wakeling, )
                           Re: Any better plan for this query?..  (Simon Riggs, )
                           Re: Any better plan for this query?..  (Scott Carey, )
                          Re: Any better plan for this query?..  (Robert Haas, )
                        Re: Any better plan for this query?..  (Tom Lane, )
                         Re: Any better plan for this query?..  (Simon Riggs, )
                          Re: Any better plan for this query?..  (Tom Lane, )
                           Re: Any better plan for this query?..  (Robert Haas, )
                            Re: Any better plan for this query?..  (Simon Riggs, )
                             Re: Any better plan for this query?..  (Robert Haas, )
                              Re: Any better plan for this query?..  (Simon Riggs, )
                     Re: Any better plan for this query?..  (Scott Carey, )
                      Re: Any better plan for this query?..  (Dimitri, )
                       Re: Any better plan for this query?..  (Scott Carey, )
                        Re: Any better plan for this query?..  (Dimitri, )
                         Re: Any better plan for this query?..  (Scott Carey, )
                          Re: Any better plan for this query?..  (Dimitri, )
               Re: Any better plan for this query?..  (Simon Riggs, )
                Re: Any better plan for this query?..  (Dimitri, )
                 Re: Any better plan for this query?..  (Robert Haas, )
                  Re: Any better plan for this query?..  (Dimitri, )
                   Re: Any better plan for this query?..  ("Kevin Grittner", )
                   Re: Any better plan for this query?..  ("Joshua D. Drake", )
                    Re: Any better plan for this query?..  (Dimitri, )
                   Re: Any better plan for this query?..  (Robert Haas, )
                    Re: Any better plan for this query?..  (Dimitri, )
               Re: Any better plan for this query?..  (Stefan Kaltenbrunner, )
                Re: Any better plan for this query?..  (Dimitri, )
                 Re: Any better plan for this query?..  (Stefan Kaltenbrunner, )
                  Re: Any better plan for this query?..  (Matthew Wakeling, )
                   Re: Any better plan for this query?..  (Simon Riggs, )
                    Re: Any better plan for this query?..  (Matthew Wakeling, )
                     Re: Any better plan for this query?..  (Stefan Kaltenbrunner, )
                     Re: Any better plan for this query?..  (Tom Lane, )
                      Re: Any better plan for this query?..  (Robert Haas, )
                  Re: Any better plan for this query?..  (Dimitri, )
   Re: Any better plan for this query?..  ("Joshua D. Drake", )
           Re: Any better plan for this query?..  (Heikki Linnakangas, )
            Re: Any better plan for this query?..  (Dimitri, )
           Re: Any better plan for this query?..  (Andres Freund, )
            Re: Any better plan for this query?..  (Alvaro Herrera, )
             Re: Any better plan for this query?..  (Scott Carey, )
              Re: Any better plan for this query?..  (Dimitri, )
               Re: Any better plan for this query?..  (Scott Carey, )
                Re: Any better plan for this query?..  (Dimitri Fontaine, )
                 Re: Any better plan for this query?..  (Dimitri, )
                 Re: Any better plan for this query?..  (Simon Riggs, )
                Re: Any better plan for this query?..  (Dimitri, )
    Re: Any better plan for this query?..  (Gregory Stark, )
     Re: Any better plan for this query?..  (Simon Riggs, )
  Re: Any better plan for this query?..  (Matthew Wakeling, )
  Re: Any better plan for this query?..  (Tom Lane, )
   Re: Any better plan for this query?..  (Greg Stark, )
   Re: Any better plan for this query?..  (Robert Haas, )
  Re: Any better plan for this query?..  (Simon Riggs, )
   Re: Any better plan for this query?..  ("Joshua D. Drake", )
    Re: Any better plan for this query?..  (Aidan Van Dyk, )
     Re: Any better plan for this query?..  (Stephen Frost, )
   Re: Any better plan for this query?..  (Robert Haas, )
   Re: Any better plan for this query?..  (Glenn Maynard, )
    Re: Any better plan for this query?..  (Dimitri, )
    Re: Any better plan for this query?..  ("Kevin Grittner", )
     Re: Any better plan for this query?..  (Dimitri, )
      Re: Any better plan for this query?..  ("Kevin Grittner", )
  Re: Any better plan for this query?..  (Dimitri Fontaine, )
   Re: Any better plan for this query?..  (Alvaro Herrera, )
  Re: Any better plan for this query?..  (Robert Haas, )
   Re: Any better plan for this query?..  (Dimitri, )
 Re: Any better plan for this query?..  (Dimitri, )
  Re: Any better plan for this query?..  (Richard Huxton, )
  Re: Any better plan for this query?..  ("Albe Laurenz", )
   Re: Any better plan for this query?..  (Dimitri, )
    Re: Any better plan for this query?..  (Kenneth Marshall, )
 Re: Any better plan for this query?..  (Merlin Moncure, )
  Re: Any better plan for this query?..  (Merlin Moncure, )
   Re: Any better plan for this query?..  (Dimitri, )
    Re: Any better plan for this query?..  (Richard Huxton, )
     Re: Any better plan for this query?..  (Ries van Twisk, )
      Re: Any better plan for this query?..  (Dimitri, )
 Re: Any better plan for this query?..  (Kenneth Marshall, )
  Re: Any better plan for this query?..  (Dimitri, )
   Re: Any better plan for this query?..  (Kenneth Marshall, )
 Re: Any better plan for this query?..  (Dimitri, )
  Re: Any better plan for this query?..  (Alvaro Herrera, )
 Re: Any better plan for this query?..  (Simon Riggs, )

Dimitri escribió:

> As well when you look on profiling technology - all such kind of
> solutions are based on the system clock frequency and have their
> limits on time resolution. On my system this limit is 0.5ms, and it's
> too big comparing to the query execution time :-)
>
> So, what I've done - I changed little bit a reference key criteria from
> = '0000000001' to < '0000000051', so instead of 20 rows I have 1000
> rows on output now,

Another thing you can try is run the query several times (like 10000 or so).

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support


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