Re: Need help in performance tuning.

От: Matthew Wakeling
Тема: Re: Need help in performance tuning.
Дата: ,
Msg-id: alpine.DEB.2.00.1007091753350.2534@aragorn.flymine.org
(см: обсуждение, исходный текст)
Ответ на: Re: Need help in performance tuning.  ("Kevin Grittner")
Ответы: Re: Need help in performance tuning.  ("Kevin Grittner")
Re: Need help in performance tuning.  (Greg Smith)
Список: pgsql-performance

Скрыть дерево обсуждения

Need help in performance tuning.  (Harpreet singh Wadhwa, )
 Re: Need help in performance tuning.  ("Kevin Grittner", )
 Re: Need help in performance tuning.  (Craig Ringer, )
  Re: Need help in performance tuning.  (Samuel Gendler, )
   Re: Need help in performance tuning.  (Tom Lane, )
    Re: Need help in performance tuning.  (Craig Ringer, )
     Re: Need help in performance tuning.  (Harpreet singh Wadhwa, )
     Re: Need help in performance tuning.  (Craig Ringer, )
     Re: Need help in performance tuning.  (Harpreet singh Wadhwa, )
      Re: Need help in performance tuning.  ("Jorge Montero", )
     Re: Need help in performance tuning.  (Bruce Momjian, )
    Re: Need help in performance tuning.  (Brad Nicholson, )
     Re: Need help in performance tuning.  ("Kevin Grittner", )
      Re: Need help in performance tuning.  (Matthew Wakeling, )
       Re: Need help in performance tuning.  ("Kevin Grittner", )
        Re: Need help in performance tuning.  (Matthew Wakeling, )
         Re: Need help in performance tuning.  ("Kevin Grittner", )
          Re: Need help in performance tuning.  ("Jorge Montero", )
           Re: Need help in performance tuning.  ("Kevin Grittner", )
         Re: Need help in performance tuning.  (Greg Smith, )
          Re: Need help in performance tuning.  ("Kevin Grittner", )
           Re: Pooling in Core WAS: Need help in performance tuning.  (Josh Berkus, )
            Re: Pooling in Core WAS: Need help in performance tuning.  (Craig Ringer, )
             Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
              Re: Pooling in Core WAS: Need help in performance tuning.  (Josh Berkus, )
               Re: Pooling in Core WAS: Need help in performance tuning.  (Tom Lane, )
                Re: Pooling in Core WAS: Need help in performance tuning.  (Matthew Wakeling, )
                 Re: Pooling in Core WAS: Need help in performance tuning.  (Craig Ringer, )
                  Re: Pooling in Core WAS: Need help in performance tuning.  ("Kevin Grittner", )
                   Re: Pooling in Core WAS: Need help in performance tuning.  (Rajesh Kumar Mallah, )
                    Re: Pooling in Core WAS: Need help in performance tuning.  (Rajesh Kumar Mallah, )
                    Re: Pooling in Core WAS: Need help in performance tuning.  (Greg Smith, )
                     Re: Pooling in Core WAS: Need help in performance tuning.  (Rajesh Kumar Mallah, )
                     Re: Pooling in Core WAS: Need help in performance tuning.  (Rajesh Kumar Mallah, )
                      Re: Pooling in Core WAS: Need help in performance tuning.  (Rajesh Kumar Mallah, )
                       Re: Pooling in Core WAS: Need help in performance tuning.  (Tatsuo Ishii, )
                        Re: Pooling in Core WAS: Need help in performance tuning.  (Rajesh Kumar Mallah, )
                         Re: Pooling in Core WAS: Need help in performance tuning.  (Tatsuo Ishii, )
                    Re: Pooling in Core WAS: Need help in performance tuning.  (Hannu Krosing, )
                  Re: Pooling in Core WAS: Need help in performance tuning.  (Hannu Krosing, )
                  Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                   Re: Pooling in Core WAS: Need help in performance tuning.  (Andres Freund, )
                    Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                     Re: Pooling in Core WAS: Need help in performance tuning.  (Tom Lane, )
                      Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                       Re: Pooling in Core WAS: Need help in performance tuning.  (Tom Lane, )
                        Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                         Re: Pooling in Core WAS: Need help in performance tuning.  (Tom Lane, )
                        Re: Pooling in Core WAS: Need help in performance tuning.  (Vitalii Tymchyshyn, )
                        Re: Pooling in Core WAS: Need help in performance tuning.  (Josh Berkus, )
                         Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                          Re: Pooling in Core WAS: Need help in performance tuning.  (Tom Lane, )
                           Re: Pooling in Core WAS: Need help in performance tuning.  (Andres Freund, )
                           Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                            Re: Pooling in Core WAS: Need help in performance tuning.  (Josh Berkus, )
                      Re: Pooling in Core WAS: Need help in performance tuning.  (Craig Ringer, )
                  Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                   Re: Pooling in Core WAS: Need help in performance tuning.  ("Joshua D. Drake", )
                    Re: Pooling in Core WAS: Need help in performance tuning.  (Hannu Krosing, )
                     Re: Pooling in Core WAS: Need help in performance tuning.  ("Joshua D. Drake", )
                      Re: Pooling in Core WAS: Need help in performance tuning.  (Hannu Krosing, )
                     Re: Pooling in Core WAS: Need help in performance tuning.  ("Joshua D. Drake", )
                   Re: Pooling in Core WAS: Need help in performance tuning.  (Hannu Krosing, )
                    Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                     Re: Pooling in Core WAS: Need help in performance tuning.  (Hannu Krosing, )
                      Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                       Re: Pooling in Core WAS: Need help in performance tuning.  (Andres Freund, )
                       Re: Pooling in Core WAS: Need help in performance tuning.  (Craig Ringer, )
                        Re: Pooling in Core WAS: Need help in performance tuning.  (Robert Haas, )
                   Re: Pooling in Core WAS: Need help in performance tuning.  (Scott Carey, )
                    Re: Pooling in Core WAS: Need help in performance tuning.  (Joshua Tolley, )
                     Re: Pooling in Core WAS: Need help in performance tuning.  (Greg Smith, )
                      Re: Pooling in Core WAS: Need help in performance tuning.  (Andres Freund, )
                      Re: Pooling in Core WAS: Need help in performance tuning.  (Craig Ringer, )
                       Re: Pooling in Core WAS: Need help in performance tuning.  (Dimitri Fontaine, )
                       Re: Pooling in Core WAS: Need help in performance tuning.  (Hannu Krosing, )
                   Re: Pooling in Core WAS: Need help in performance tuning.  ("Joshua D. Drake", )
                Re: Pooling in Core WAS: Need help in performance tuning.  (Dimitri Fontaine, )
                 Re: Pooling in Core WAS: Need help in performance tuning.  (Magnus Hagander, )
             Re: Pooling in Core WAS: Need help in performance tuning.  (Scott Carey, )
            Re: Pooling in Core WAS: Need help in performance tuning.  (Samuel Gendler, )
          Re: Need help in performance tuning.  (Jesper Krogh, )
           Re: Need help in performance tuning.  (Greg Smith, )
            Re: Need help in performance tuning.  ("Pierre C", )
     Re: Need help in performance tuning.  (Mark Kirkwood, )
    Re: Need help in performance tuning.  (Robert Haas, )
    Re: Need help in performance tuning.  (Hannu Krosing, )
     Re: Need help in performance tuning.  (Scott Marlowe, )
      Re: Need help in performance tuning.  ("Kevin Grittner", )
       Re: Need help in performance tuning.  (Hannu Krosing, )
 Re: Pooling in Core WAS: Need help in performance tuning.  (Rajesh Kumar Mallah, )

On Fri, 9 Jul 2010, Kevin Grittner wrote:
>> Interesting idea. As far as I can see, you are suggesting solving
>> the too many connections problem by allowing lots of connections,
>> but only allowing a certain number to do anything at a time?
>
> Right.

I think in some situations, this arrangement would be an advantage.
However, I do not think it will suit the majority of situations, and could
reduce the performance when the user doesn't need the functionality,
either because they have a pool already, or they don't have many
connections.

No, I don't have any numbers.

>> 1. Pool can be on a separate machine or machines, spreading load.
>
> Sure, but how would you do that with a built-in implementation?

That's my point exactly. If you have an external pool solution, you can
put it somewhere else - maybe on multiple somewhere elses.

>> 3. A large amount of the overhead is sometimes connection setup,
>>    which this would not solve. A pool has cheap setup.
>
> This would probably be most useful where the client held a
> connection for a long time, not for the "login for each database
> transaction" approach.  I'm curious how often you think application
> software uses that approach.

What you say is true. I don't know how often that is, but it seems to be
those times that people come crying to the mailing list.

>> 4. This could cause Postgres backends to be holding onto large
>>    amounts of memory while being prevented from doing anything,
>>    which is a bad use of resources.
>
> Isn't this point 2 again?

Kind of. Yes. Point 2 was simple overhead. This point was that the backend
may have done a load of query-related allocation, and then been stopped.

>> 7. That lock would have a metric *($!-load of contention.
>
> Here I doubt you.  It would be held for such short periods that I
> suspect that collisions would be relatively infrequent compared to
> some of the other locks we use.  As noted in the email, it may
> actually normally be an "increment and test" within an existing
> locked block.

Fair enough. It may be much less of a problem than I had previously
thought.

Matthew

--
 Change is inevitable, except from vending machines.


В списке pgsql-performance по дате сообщения:

От: Greg Smith
Дата:
Сообщение: Re: Need help in performance tuning.
От: Tom Lane
Дата:
Сообщение: Re: Index usage with functions in where condition