Re: [HACKERS] Postgres Speed or lack thereof

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От Tom Lane
Тема Re: [HACKERS] Postgres Speed or lack thereof
Дата
Msg-id 18955.917277865@sss.pgh.pa.us
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Ответ на Re: [HACKERS] Postgres Speed or lack thereof  (Vadim Mikheev <vadim@krs.ru>)
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Vadim Mikheev <vadim@krs.ru> writes:
> Tom Lane wrote:
>> I don't think we can or should stop using malloc(), but we can
>> ask it for large blocks and do our own allocations inside those
>> blocks --- was that what you meant?

> No. We could ask brk() for large blocks.

I think that would be a bad idea.  brk() is a Unix-ism; I doubt it's
supported on Win NT, for example.  malloc() is a lot more portable.

Another potential portability issue is whether malloc() will coexist
with calling brk() ourselves.  (It *ought* to, but I can believe that
the feature might be broken on some platforms, since it's so seldom
exercised...)  We can't stop all uses of malloc(), because parts of the
C library use it --- stdio, qsort, putenv all do on my machine.

If we're going to grab large chunks and keep them, then any small
inefficiency in doing the grabbing isn't really worth worrying about;
so I don't see the need to bypass malloc() for that.
        regards, tom lane


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