From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nikita Glukhov <n.gluhov@postgrespro.ru>
Cc: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Darafei Praliaskouski <me@komzpa.net>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Fedor Sigaev <teodor@sigaev.ru>
Subject: Re: compress method for spgist - 2
Date: Wed, 20 Sep 2017 18:34:47 -0400
Message-ID: <5454.1505946887@sss.pgh.pa.us> (raw)
In-Reply-To: <60e048d3-aa29-8289-5438-3b0c4c1d8d84@postgrespro.ru>
References: <54907069.1030506@sigaev.ru>
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Nikita Glukhov <n.gluhov@postgrespro.ru> writes:
> On 20.09.2017 23:19, Alexander Korotkov wrote:
>> On Wed, Sep 20, 2017 at 11:07 PM, Tom Lane <tgl@sss.pgh.pa.us
>> <mailto:tgl@sss.pgh.pa.us>> wrote:
>>> Maybe I'm missing something, but it appears to me that it's
>>> impossible for bbox->low.x to be NaN unless circle->center.x and/or
>>> circle->radius is a NaN, in which case bbox->high.x would also have been computed as a NaN,
>>> making the swap entirely useless.
> It is possible for bbox->low.x to be NaN when circle->center.x is and
> circle->radius are both +Infinity. Without this float-order-preserving
> swapping
> one regression test for KNN with ORDER BY index will be totally broken
> (you can
> try it: https://github.com/glukhovn/postgres/tree/knn).
If that's the reasoning, not having a comment explaining it is
inexcusable. Do you really think people will understand what
the code is doing?
regards, tom lane
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Cc: tgl@sss.pgh.pa.us, n.gluhov@postgrespro.ru, aekorotkov@gmail.com, me@komzpa.net, hlinnaka@iki.fi, teodor@sigaev.ru
Subject: Re: compress method for spgist - 2
In-Reply-To: <5454.1505946887@sss.pgh.pa.us>
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