Re: seq scan cache vs. index cache smackdown

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От Bruce Momjian
Тема Re: seq scan cache vs. index cache smackdown
Дата
Msg-id 200502190411.j1J4B8T15005@candle.pha.pa.us
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Ответ на Re: seq scan cache vs. index cache smackdown  ("Magnus Hagander" <mha@sollentuna.net>)
Ответы Re: seq scan cache vs. index cache smackdown  (PFC <lists@boutiquenumerique.com>)
Список pgsql-performance
Magnus Hagander wrote:
> I don't think that's correct either. Scatter/Gather I/O is used to SQL
> Server can issue reads for several blocks from disks into it's own
> buffer cache with a single syscall even if these buffers are not
> sequential. It did make significant performance improvements when they
> added it, though.
>
> (For those not knowing - it's ReadFile/WriteFile where you pass an array
> of "this many bytes to this address" as parameters)

Isn't that like the BSD writev()/readv() that Linux supports also?  Is
that something we should be using on Unix if it is supported by the OS?

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