Re: Very high effective_cache_size == worse performance?

От: Kevin Grittner
Тема: Re: Very high effective_cache_size == worse performance?
Дата: ,
Msg-id: 4BCDA94E0200002500030BF8@gw.wicourts.gov
(см: обсуждение, исходный текст)
Ответ на: Re: Very high effective_cache_size == worse performance?  (David Kerr)
Ответы: Re: Very high effective_cache_size == worse performance?  (David Kerr)
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", )

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


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