Re: improving GROUP BY estimation

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От Dean Rasheed
Тема Re: improving GROUP BY estimation
Дата
Msg-id CAEZATCWQ3L8rKsp0+GbO-7D2weYjxZU3668fJx1ZgoVa_QL1LA@mail.gmail.com
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Ответ на Re: improving GROUP BY estimation  (Tomas Vondra <tomas.vondra@2ndquadrant.com>)
Ответы Re: improving GROUP BY estimation  (Tom Lane <tgl@sss.pgh.pa.us>)
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On 30 March 2016 at 14:03, Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote:
> Attached is v4 of the patch

Thanks, I think this is good to go, except that I think we need to use
pow() rather than powl() because AIUI powl() is new to C99, and so
won't necessarily be available on all supported platforms. I don't
think we need worry about loss of precision, since that would only be
an issue if rel->rows / rel->tuples were smaller than maybe 10^-14 or
so, and it seems unlikely we'll get anywhere near that any time soon.

I think this is a good, well thought-out change, so unless anyone
objects I'll push it (probably this weekend).

Regards,
Dean



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