| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Alfred Perlstein <bright(at)wintelcom(dot)net> |
| Cc: | Matthias Urlichs <smurf(at)noris(dot)de>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Bryan White <bryan(at)arcamax(dot)com>, Jesse Estevez <jestevez(at)travel-italy(dot)com>, pgsql-general <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: PG 7.0 is 2.5 times slower running a big report |
| Date: | 2000-05-26 14:52:30 |
| Message-ID: | 200005261452.KAA22771@candle.pha.pa.us |
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| Lists: | pgsql-general |
> 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(at)candle(dot)pha(dot)pa(dot)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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