Re: PG 7.0 is 2.5 times slower running a big report

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От Bruce Momjian
Тема Re: PG 7.0 is 2.5 times slower running a big report
Дата
Msg-id 200005261452.KAA22771@candle.pha.pa.us
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Ответ на Re: PG 7.0 is 2.5 times slower running a big report  (Alfred Perlstein <bright@wintelcom.net>)
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> The statement:
>
> > > BSD file systems turn off prefetch only if prefetched blocks remain
> > > unused.
>
> is false for FreeBSD afaik.
>
> FreeBSD tracks how often sequential access happens and will retry it
> as the file's access trend indicates.  It can flip back and forth from
> readahead and non-readahead.

Yes, read my later posting describing the actual algorithm.  Let me know
if it is wrong.

--
  Bruce Momjian                        |  http://www.op.net/~candle
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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