Re: improving GROUP BY estimation - Mailing list pgsql-hackers

From Dean Rasheed
Subject Re: improving GROUP BY estimation
Date
Msg-id CAEZATCWQ3L8rKsp0+GbO-7D2weYjxZU3668fJx1ZgoVa_QL1LA@mail.gmail.com
Whole thread Raw
In response to Re: improving GROUP BY estimation  (Tomas Vondra <tomas.vondra@2ndquadrant.com>)
Responses Re: improving GROUP BY estimation
List pgsql-hackers
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



pgsql-hackers by date:

Previous
From: Alvaro Herrera
Date:
Subject: Re: [PATCH] Phrase search ported to 9.6
Next
From: Tom Lane
Date:
Subject: Re: PATCH: index-only scans with partial indexes