Re: Very high effective_cache_size == worse performance?

От: David Kerr
Тема: Re: Very high effective_cache_size == worse performance?
Дата: ,
Msg-id: 20100420184614.GD53489@mr-paradox.net
(см: обсуждение, исходный текст)
Ответ на: Re: Very high effective_cache_size == worse performance?  ("Kevin Grittner")
Список: pgsql-performance

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Very high effective_cache_size == worse performance?  (David Kerr, )
 Re: Very high effective_cache_size == worse performance?  ("Joshua D. Drake", )
 Re: Very high effective_cache_size == worse performance?  (Robert Haas, )
  Re: Very high effective_cache_size == worse performance?  (David Kerr, )
   Re: Very high effective_cache_size == worse performance?  (Nikolas Everett, )
    Re: Very high effective_cache_size == worse performance?  (Kris Jurka, )
    Re: Very high effective_cache_size == worse performance?  (David Kerr, )
     Re: Very high effective_cache_size == worse performance?  (Scott Marlowe, )
      Re: Very high effective_cache_size == worse performance?  (David Kerr, )
       Re: Very high effective_cache_size == worse performance?  (Scott Marlowe, )
        Re: Very high effective_cache_size == worse performance?  (David Kerr, )
       Re: Very high effective_cache_size == worse performance?  (Scott Marlowe, )
       Re: Very high effective_cache_size == worse performance?  (Greg Smith, )
        Re: Very high effective_cache_size == worse performance?  (David Kerr, )
         Re: Very high effective_cache_size == worse performance?  (Greg Smith, )
   Re: Very high effective_cache_size == worse performance?  (Robert Haas, )
    Re: Very high effective_cache_size == worse performance?  (David Kerr, )
     Re: Very high effective_cache_size == worse performance?  (Scott Marlowe, )
      Re: Very high effective_cache_size == worse performance?  (Scott Carey, )
   Re: Very high effective_cache_size == worse performance?  ("Kevin Grittner", )
    Re: Very high effective_cache_size == worse performance?  (David Kerr, )
 Re: Very high effective_cache_size == worse performance?  (Scott Marlowe, )
  Re: Very high effective_cache_size == worse performance?  (Scott Marlowe, )
 Re: Very high effective_cache_size == worse performance?  ("Joshua D. Drake", )

On Tue, Apr 20, 2010 at 01:17:02PM -0500, Kevin Grittner wrote:
- David Kerr <> wrote:
-
- > Incidentally the code is written to work like this :
- >
- > while (read X lines in file){
- > Process those lines.
- > write lines to DB.
- > }
-
- Unless you're selecting from multiple database tables in one query,
- effective_cache_size shouldn't make any difference.  There's
- probably some other reason for the difference.
-
- A couple wild shots in the dark:
-
- Any chance the source files were cached the second time, but not the
- first?
-
- Do you have a large checkpoint_segments setting, and did the second
- run without a new initdb?
-
- -Kevin

no i don't think the files would be cached the 2nd time. I ran it multiple times
and got the same performance each time. It wasn't until i changed the parameter
that performance got better.

I've got checkpoint_segments = 300

Dave


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