Re: compress method for spgist - 2

On Thu, Sep 21, 2017 at 2:06 AM, Darafei "Komяpa" Praliaskouski <
me(at)komzpa(dot)net> wrote:

> It is possible for bbox->low.x to be NaN when circle->center.x is and
>> circle->radius are both +Infinity.
>>
>
> What is rationale behind this circle?
>

I would prefer to rather forbid any geometries with infs and nans.
However, then upgrade process will suffer. User with such geometries would
get errors during dump/restore, pg_upgraded instances would still contain
invalid values...

> It seems to me that any circle with radius of any Infinity should become a
> [-Infinity .. Infinity, -Infinity .. Infinity] box.Then you won't have
> NaNs, and index structure shouldn't be broken.
>

We probably should produce [-Infinity .. Infinity, -Infinity .. Infinity]
box for any geometry containing inf or nan. That MBR would be founded for
any query, saying: "index can't help you for this kind value, only recheck
can deal with that". Therefore, we would at least guarantee that results
of sequential scan and index scan are the same.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company