Re: Any better plan for this query?..

From: Matthew Wakeling
Subject: Re: Any better plan for this query?..
Date: ,
Msg-id: alpine.DEB.2.00.0905121553370.2341@aragorn.flymine.org
(view: Whole thread, Raw)
In response to: Re: Any better plan for this query?..  (Stefan Kaltenbrunner)
Responses: Re: Any better plan for this query?..  (Simon Riggs)
List: pgsql-performance

Tree view

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, )

On Tue, 12 May 2009, Stefan Kaltenbrunner wrote:
> But what I get from your answer is that you are basically doing one
> connect/disconnect per client and the testcase you are talking about has 256
> clients?

Correct me if I'm wrong, but won't connect operations be all handled by a
single thread - the parent postmaster? There's your scalability problem
right there. Also, spawning a new backend process is an awful lot of
overhead to run just one query.

As far as I can see, it's quite understandable for MySQL to perform better
than PostgreSQL in these circumstances, as it has a smaller simpler
backend to start up each time. If you really want to get a decent
performance out of Postgres, then use long-lived connections (which most
real-world use cases will do) and prepare your queries in advance with
parameters.

Matthew

--
 import oz.wizards.Magic;
   if (Magic.guessRight())...           -- Computer Science Lecturer


pgsql-performance by date:

From: Simon Riggs
Date:
Subject: Re: Any better plan for this query?..
From: Simon Riggs
Date:
Subject: Re: Any better plan for this query?..