Re: Possible to improve query plan?

От: Jeremy Palmer
Тема: Re: Possible to improve query plan?
Дата: ,
Msg-id: 666FB8D75E95AE42965A0E76A5E5337E06D2D27BC3@prdlsmmsg01.ad.linz.govt.nz
(см: обсуждение, исходный текст)
Ответ на: Re: Possible to improve query plan?  ("Kevin Grittner")
Список: pgsql-performance

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Possible to improve query plan?  (Jeremy Palmer, )
   Re: Possible to improve query plan?  (Andy Colson, )
    Re: Possible to improve query plan?  (Jeremy Palmer, )
   Re: Possible to improve query plan?  ("Ing. Marcos Ortiz Valmaseda", )
    Re: Possible to improve query plan?  (Jeremy Palmer, )
   Re: Possible to improve query plan?  ("Kevin Grittner", )
    Re: Possible to improve query plan?  (Robert Haas, )
     Re: Possible to improve query plan?  ("Kevin Grittner", )
      Re: Possible to improve query plan?  (Tom Lane, )
       Re: Possible to improve query plan?  ("Kevin Grittner", )
        Re: Possible to improve query plan?  (Jeremy Palmer, )
         Re: Possible to improve query plan?  ("Kevin Grittner", )
          Re: Possible to improve query plan?  (Cédric Villemain, )
         Re: Possible to improve query plan?  ("Kevin Grittner", )
          Re: Possible to improve query plan?  (Jeremy Palmer, )
     Re: Possible to improve query plan?  (Tom Lane, )

Thanks heaps for the advice. I will do some benchmarks to see how long it takes to cluster all of the database tables.

Cheers,
Jeremy

-----Original Message-----
From: Kevin Grittner [mailto:]
Sent: Tuesday, 25 January 2011 1:02 p.m.
To: Jeremy Palmer; Tom Lane
Cc: Robert Haas; ; 
Subject: RE: [PERFORM] Possible to improve query plan?

Jeremy Palmer <> wrote:

> My only question is how often will I need to re-cluster the
> table, because it comes at quite a cost.

I probably should have mentioned that the CLUSTER will run faster if
the data is already mostly in the right sequence.  You'll be doing a
nearly sequential pass over the heap, which should minimize seek
time, especially if the OS notices the pattern and starts doing
sequential read-ahead.

-Kevin
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