Re: Any experience using "shake" defragmenter?

От: Florian Weimer
Тема: Re: Any experience using "shake" defragmenter?
Дата: ,
Msg-id: 82k4hl81m0.fsf@mid.bfk.de
(см: обсуждение, исходный текст)
Ответ на: Re: Any experience using "shake" defragmenter?  ("Mark Felder")
Список: pgsql-performance

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Any experience using "shake" defragmenter?  (Mladen Gogala, )
 Re: Any experience using "shake" defragmenter?  ("Mark Felder", )
  Re: Any experience using "shake" defragmenter?  (Marcin Mirosław, )
   Re: Any experience using "shake" defragmenter?  (Mladen Gogala, )
  Re: Any experience using "shake" defragmenter?  (Mladen Gogala, )
   Re: Any experience using "shake" defragmenter?  (Lew, )
   Re: Any experience using "shake" defragmenter?  (Mark Kirkwood, )
  Re: Any experience using "shake" defragmenter?  (Florian Weimer, )
 Re: Any experience using "shake" defragmenter?  (Florian Weimer, )
 Re: Any experience using "shake" defragmenter?  (Lew, )
 Re: Any experience using "shake" defragmenter?  (Greg Smith, )
  Re: Any experience using "shake" defragmenter?  (Jon Nelson, )
   Re: Any experience using "shake" defragmenter?  (Grant Johnson, )
    Re: Any experience using "shake" defragmenter?  (Robert Haas, )

* Mark Felder:

> Why do you feel the need to defrag your *nix box?

Some file systems (such as XFS) read the whole extent list into RAM
when a file is opened.  When the extend list is long due to
fragmentation, this can take a *long* time (in the order of minutes
with multi-gigabyte Oracle Berkeley DB files).  This phenomenon is
less pronounced with PostgreSQL because it splits large relations into
one-gigabyte chunks, and it writes the files sequentally.  But a small
effect is probably still there.

--
Florian Weimer                <>
BFK edv-consulting GmbH       http://www.bfk.de/
Kriegsstraße 100              tel: +49-721-96201-1
D-76133 Karlsruhe             fax: +49-721-96201-99


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