Re: I/O on select count(*)

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От Tom Lane
Тема Re: I/O on select count(*)
Дата
Msg-id 5697.1211211478@sss.pgh.pa.us
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Ответ на Re: I/O on select count(*)  (Bruce Momjian <bruce@momjian.us>)
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Bruce Momjian <bruce@momjian.us> writes:
> Matthew Wakeling wrote:
>> Does it really take that long to zero out 8kB of RAM? I thought CPUs were
>> really quick at doing that!

> Yea, that was my assumption too.

You have to write the page (to be sure there is space for it on disk)
not only zero it.

This design is kind of a holdover, though, from back when we had one
ever-growing clog file.  Today I'd be inclined to think about managing
it more like pg_xlog, ie, have some background process pre-create a
whole segment file at a time.

            regards, tom lane

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