Re: PostgreSQL 8.4 performance tuning questions

От: Tom Lane
Тема: Re: PostgreSQL 8.4 performance tuning questions
Дата: ,
Msg-id: 6127.1249325797@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey)
Ответы: Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey)
Re: PostgreSQL 8.4 performance tuning questions  (Merlin Moncure)
Список: pgsql-performance

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PostgreSQL 8.4 performance tuning questions  (Rauan Maemirov, )
 Re: PostgreSQL 8.4 performance tuning questions  (, )
  Re: PostgreSQL 8.4 performance tuning questions  (Rauan Maemirov, )
   Re: PostgreSQL 8.4 performance tuning questions  (Merlin Moncure, )
 Re: PostgreSQL 8.4 performance tuning questions  (, )
  Re: PostgreSQL 8.4 performance tuning questions  (Rauan Maemirov, )
  Re: PostgreSQL 8.4 performance tuning questions  (Steve Crawford, )
   Re: PostgreSQL 8.4 performance tuning questions  ("Kevin Grittner", )
    Re: PostgreSQL 8.4 performance tuning questions  (Steve Crawford, )
    Re: PostgreSQL 8.4 performance tuning questions  (Matthew Wakeling, )
     Re: PostgreSQL 8.4 performance tuning questions  ("Kevin Grittner", )
      Re: PostgreSQL 8.4 performance tuning questions  (Tom Lane, )
       Re: PostgreSQL 8.4 performance tuning questions  ("Kevin Grittner", )
       Re: PostgreSQL 8.4 performance tuning questions  ("Kevin Grittner", )
        Re: PostgreSQL 8.4 performance tuning questions  (Stefan Kaltenbrunner, )
         Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
          Re: PostgreSQL 8.4 performance tuning questions  (Stefan Kaltenbrunner, )
        Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
         Re: PostgreSQL 8.4 performance tuning questions  ("Kevin Grittner", )
          Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
           Re: PostgreSQL 8.4 performance tuning questions  ("Kevin Grittner", )
            Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
             Re: PostgreSQL 8.4 performance tuning questions  ("Kevin Grittner", )
             Re: PostgreSQL 8.4 performance tuning questions  (Tom Lane, )
              Re: PostgreSQL 8.4 performance tuning questions  ("Kevin Grittner", )
               Re: PostgreSQL 8.4 performance tuning questions  (Rauan Maemirov, )
              Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
               Re: PostgreSQL 8.4 performance tuning questions  (Tom Lane, )
                Re: PostgreSQL 8.4 performance tuning questions  (Greg Stark, )
                 Re: PostgreSQL 8.4 performance tuning questions  ("Kevin Grittner", )
                 Re: PostgreSQL 8.4 performance tuning questions  (Tom Lane, )
                  Re: PostgreSQL 8.4 performance tuning questions  (PFC, )
                   Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
                    Re: PostgreSQL 8.4 performance tuning questions  (Tom Lane, )
                     Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
                     Re: PostgreSQL 8.4 performance tuning questions  (Merlin Moncure, )
                      Re: PostgreSQL 8.4 performance tuning questions  (PFC, )
                       Re: PostgreSQL 8.4 performance tuning questions  (Merlin Moncure, )
                        Re: PostgreSQL 8.4 performance tuning questions  (Alvaro Herrera, )
                         Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
                          Re: PostgreSQL 8.4 performance tuning questions  (Tom Lane, )
                           Re: PostgreSQL 8.4 performance tuning questions  (Merlin Moncure, )
                            Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
                    Re: PostgreSQL 8.4 performance tuning questions  (PFC, )
            Re: PostgreSQL 8.4 performance tuning questions  (Tom Lane, )
         Re: PostgreSQL 8.4 performance tuning questions  (Arjen van der Meijden, )
       Re: PostgreSQL 8.4 performance tuning questions  (Stefan Kaltenbrunner, )
        Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
         Re: PostgreSQL 8.4 performance tuning questions  (Tom Lane, )
          Re: PostgreSQL 8.4 performance tuning questions  (Scott Carey, )
 Re: PostgreSQL 8.4 performance tuning questions  (Greg Smith, )
  Re: PostgreSQL 8.4 performance tuning questions  (Scott Marlowe, )
   Re: PostgreSQL 8.4 performance tuning questions  (Rauan Maemirov, )

Scott Carey <> writes:
> I get very different (contradictory) behavior.  Server with fast RAID, 32GB
> RAM, 2 x 4 core 3.16Ghz Xeon 54xx CPUs.  CentOS 5.2
> 8.3.6
> No disk wait time during any test.  One test beforehand was used to prime
> the disk cache.
> 100% CPU in the below means one core fully used.  800% means the system is
> fully loaded.

> pg_dump > file  (on a subset of the DB with lots of tables with small
> tuples)
> 6m 27s, 4.9GB;  12.9MB/sec
> 50% CPU in postgres, 50% CPU in pg_dump

> pg_dump -Fc > file.gz
> 9m6s, output is 768M  (6.53x compression); 9.18MB/sec
> 30% CPU in postgres, 70% CPU in pg_dump

> pg_dump | gzip > file.2.gz
> 6m22s, 13MB/sec.
> 50% CPU in postgres, 50% Cpu in pg_dump, 50% cpu in gzip

I don't see anything very contradictory here.  What you're demonstrating
is that it's nice to be able to throw a third CPU at the compression
part of the problem.  That's likely to remain true if we shift to a
different compression algorithm.  I suspect if you substituted lzo for
gzip in the third case, the picture wouldn't change very much.

            regards, tom lane


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