Re: Scalability in postgres

От: Flavio Henrique Araque Gurgel
Тема: Re: Scalability in postgres
Дата: ,
Msg-id: 10004459.141243560273700.JavaMail.flavio@presente
(см: обсуждение, исходный текст)
Ответ на: Re: Scalability in postgres  (Fabrix)
Ответы: Re: Scalability in postgres  (Greg Smith)
Список: pgsql-performance

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Scalability in postgres  (Fabrix, )
 Re: Scalability in postgres  (David Rees, )
  Re: Scalability in postgres  (Fabrix, )
   Re: Scalability in postgres  (Scott Mead, )
    Re: Scalability in postgres  (Fabrix, )
   Re: Scalability in postgres  (Scott Marlowe, )
 Re: Scalability in postgres  (Scott Marlowe, )
  Re: Scalability in postgres  (Fabrix, )
  Re: Scalability in postgres  (Flavio Henrique Araque Gurgel, )
   Re: Scalability in postgres  (Fabrix, )
    Re: Scalability in postgres  (Scott Marlowe, )
    Re: Scalability in postgres  (Flavio Henrique Araque Gurgel, )
     Re: Scalability in postgres  (Greg Smith, )
      Re: Scalability in postgres  (Grzegorz Jaśkiewicz, )
       Re: Scalability in postgres  (Scott Marlowe, )
       Re: Scalability in postgres  (Scott Marlowe, )
        Re: Scalability in postgres  (Grzegorz Jaśkiewicz, )
         Re: Scalability in postgres  (Scott Marlowe, )
          Re: Scalability in postgres  (Grzegorz Jaśkiewicz, )
           Re: Scalability in postgres  (Scott Marlowe, )
            Re: Scalability in postgres  (Grzegorz Jaśkiewicz, )
             Re: Scalability in postgres  (Scott Marlowe, )
         Re: Scalability in postgres  (Ron Mayer, )
       Re: Scalability in postgres  (Greg Smith, )
        Re: Scalability in postgres  (Scott Mead, )
         Re: Scalability in postgres  (Scott Marlowe, )
         Re: Scalability in postgres  (Fabrix, )
          Re: Scalability in postgres  (Scott Mead, )
      Re: Scalability in postgres  (Fabrix, )
       Re: Scalability in postgres  (Greg Smith, )
      Re: Scalability in postgres  (Scott Carey, )
       Re: Scalability in postgres  (Greg Smith, )
        Re: Scalability in postgres  (Scott Marlowe, )
         Re: Scalability in postgres  (Greg Smith, )
       Re: Scalability in postgres  (Fabrix, )
        Re: Scalability in postgres  (Scott Carey, )
      Re: Scalability in postgres  (James Mansion, )
       Re: Scalability in postgres  ("Kevin Grittner", )
        Re: Scalability in postgres  (Dimitri, )
         Re: Scalability in postgres  ("Kevin Grittner", )
          Re: Scalability in postgres  (Scott Carey, )
           Re: Scalability in postgres  (Robert Haas, )
            Re: Scalability in postgres  (Scott Carey, )
             Re: Scalability in postgres  (Robert Haas, )
              Re: Scalability in postgres  (Scott Carey, )
               Re: Scalability in postgres  (Robert Haas, )
              Re: Scalability in postgres  (, )
               Re: Scalability in postgres  (Robert Haas, )
                Re: Scalability in postgres  (Greg Smith, )
                 Re: Scalability in postgres  (, )
                  Re: Scalability in postgres  (Robert Haas, )
                 Re: Scalability in postgres  (Mark Mielke, )
                  Re: Scalability in postgres  (Greg Smith, )
                   Re: Scalability in postgres  (Robert Haas, )
                 Re: Scalability in postgres  (Craig James, )
          Re: Scalability in postgres  (Dimitri, )
           Re: Scalability in postgres  (Marc Cousin, )
        Re: Scalability in postgres  (James Mansion, )
         Re: Scalability in postgres  ("Kevin Grittner", )
          Re: Scalability in postgres  (Mark Mielke, )
           Re: Scalability in postgres  (, )
            Re: Scalability in postgres  (Mark Mielke, )
             Re: Scalability in postgres  (, )
           Re: Scalability in postgres  ("Kevin Grittner", )
           Re: Scalability in postgres  (Greg Smith, )
          Re: Scalability in postgres  (Scott Carey, )
           Re: Scalability in postgres  ("Kevin Grittner", )
         Re: Scalability in postgres  ("Kevin Grittner", )
 Re: Scalability in postgres  (Jeff Janes, )
  Re: Scalability in postgres  (Tom Lane, )
   Re: Scalability in postgres  (Jeff Janes, )
  Re: Scalability in postgres  ("", )

I would ask for your kernel version. uname -a please?

> sure, and thanks for you answer Flavio...
>

> uname -a
> Linux SERVIDOR-A 2.6.18-92.el5 #1 SMP Tue Apr 29 13:16:15 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux
>  
> cat /etc/redhat-release
> Red Hat Enterprise Linux Server release 5.2 (Tikanga)
>

I had the same problem you're saying with Debian Etch 2.6.18 when the system needed more then 1000 connections.

>
>
>
> It was possible to make the context work better with 2.4.24 with kswapd patched around here. 1600 connections working fine at this moment.

> 2.4 is very old, or not?

My mistake. It is 2.6.24
We had to apply the kswapd patch also. It's important specially if you see your system % going as high as 99% in top and loosing the machine's control. I have read something about 2.6.28 had this patch accepted in mainstream.

>
> Try to lower your memory requirements too. Linux kernel needs some space to page and scale up. Install some more memory otherwise.
>

> how much?
> already I have a lot of  memory installed in the server 128GB.

Here we have 16GB. I had to limit PostgreSQL memory requirements (shared_buffers + max_connections * work_mem) to about 40% RAM. effective_cache_size was not an issue and about 30% of RAM is working fine. Of course the cache is a matter of your context.
Since we have fast queries with low memory requirements for sorting or nested loops, 1.5MB for work_mem was enough around here. 2GB of shared buffers worked like a charm but it's too low for the indexes I work with and I'm planning to increase it when I have more RAM.

Flavio
>

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