Re: seq scan woes

От Dan Langille
Тема Re: seq scan woes
Msg-id 40C493F8.1181.48F37175@localhost
обсуждение исходный текст
Ответ на seq scan woes  ("Dan Langille")
Ответы Re: seq scan woes  (Rod Taylor)
Список pgsql-performance
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seq scan woes  ("Dan Langille", )
 Re: seq scan woes  ("Dan Langille", )
  Re: seq scan woes  ("Dan Langille", )
  Re: seq scan woes  ("Dan Langille", )
   Re: seq scan woes  ("Dan Langille", )
  Re: seq scan woes  (Rod Taylor, )
 Re: seq scan woes  (Rod Taylor, )
On 7 Jun 2004 at 16:00, Rod Taylor wrote:

> On Mon, 2004-06-07 at 15:45, Dan Langille wrote:
> > A production system has had a query recently degrade in performance.
> > What once took < 1s now takes over 1s.  I have tracked down the
> > problem to a working example.
> What changes have you made to postgresql.conf?

Nothing recently (ie. past few months). Nothing at all really.
Perhaps I need to start tuning that.

> Could you send explain analyse again with SEQ_SCAN enabled but with
> nested loops disabled?



> Off the cuff? I might hazard a guess that effective_cache is too low or
> random_page_cost is a touch too high. Probably the former.

I grep'd postgresql.conf:

#effective_cache_size = 1000    # typically 8KB each
#random_page_cost = 4           # units are one sequential page fetch cost

NOTE: both above are commented out.

Thank you
Dan Langille :
BSDCan -

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