Re: Database size Vs performance degradation

От: Matthew Wakeling
Тема: Re: Database size Vs performance degradation
Дата: ,
Msg-id: Pine.LNX.4.64.0807301331550.4250@aragorn.flymine.org
(см: обсуждение, исходный текст)
Ответ на: Database size Vs performance degradation  ("Dave North")
Ответы: Re: Database size Vs performance degradation  ("Dave North")
Список: pgsql-performance

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Database size Vs performance degradation  ("Dave North", )
 Re: Database size Vs performance degradation  (Richard Huxton, )
  Re: Database size Vs performance degradation  ("Dave North", )
   Re: Database size Vs performance degradation  (Tom Lane, )
   Re: Database size Vs performance degradation  (Richard Huxton, )
 Re: Database size Vs performance degradation  (Matthew Wakeling, )
  Re: Database size Vs performance degradation  ("Dave North", )
 Re: Database size Vs performance degradation  (Valentin Bogdanov, )
  Re: Database size Vs performance degradation  ("Dave North", )
   Re: Database size Vs performance degradation  (Craig James, )
    Re: Database size Vs performance degradation  (Matthew Wakeling, )
     Re: Database size Vs performance degradation  (Mark Roberts, )
      Re: Database size Vs performance degradation  (Tom Lane, )
       Re: Database size Vs performance degradation  (Mark Roberts, )
        Re: Database size Vs performance degradation  (Andrzej Zawadzki, )
         Re: Database size Vs performance degradation  (Matthew Wakeling, )
          Re: Database size Vs performance degradation  ("Fernando Ike", )
        Plz Heeeelp! performance settings  (dforum, )
         Re: Plz Heeeelp! performance settings  ("Merlin Moncure", )
          Re: Plz Heeeelp! performance settings  (dforum, )
           Re: Plz Heeeelp! performance settings  (Richard Huxton, )
            Re: Plz Heeeelp! performance settings  (dforums, )
             Re: Plz Heeeelp! performance settings  (Richard Huxton, )
              Re: Plz Heeeelp! performance settings  (dforums, )
               Re: Plz Heeeelp! performance settings  (Richard Huxton, )
               Re: Plz Heeeelp! performance settings  ("Merlin Moncure", )
   Re: Database size Vs performance degradation  (Mark Roberts, )
 Re: Database size Vs performance degradation  (Greg Smith, )
  Re: Database size Vs performance degradation  ("Dave North", )
   Re: Database size Vs performance degradation  (Guillaume Lelarge, )
 Re: Database size Vs performance degradation  (Miernik, )
  Re: Database size Vs performance degradation  (Mark Roberts, )
 Re: Plz Heeeelp! performance settings  (Richard Huxton, )

On Wed, 30 Jul 2008, Dave North wrote:
> Running on HP DL380 w/ 4GB RAM, dual 10K HDDs in RAID 0+1

> Checking the stats, the DB size is around 7.5GB;

Doesn't fit in RAM.

> ...after the load, the DB size was around 2.7GB

Does fit in RAM.

> One observation I've made on the DB system is the disk I/O seems
> dreadfully slow...we're at around 75% I/O wait sometimes and the read
> rates seem quite slow (hdparm says around 2.2MB/sec - 20MB/sec for
> un-cached reads).

That's incredibly slow in this day and age, especially from 10krpm HDDs.
Definitely worth investigating.

However, I think vacuuming more agressively is going to be your best win
at the moment.

Matthew

--
Patron: "I am looking for a globe of the earth."
Librarian: "We have a table-top model over here."
Patron: "No, that's not good enough. Don't you have a life-size?"
Librarian: (pause) "Yes, but it's in use right now."


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