Re: Infinite Interval

On Mon, Jan 2, 2023 at 1:21 PM Joseph Koshakow <koshy44(at)gmail(dot)com> wrote:
>
> On Sat, Dec 31, 2022 at 12:09 AM jian he <jian(dot)universality(at)gmail(dot)com> wrote:
> > In float8, select float8 'inf' / float8 'inf' return NaN. Now in your patch select interval 'infinity' / float8 'infinity'; returns infinity.
> > I am not sure it's right. I found this related post (https://math.stackexchange.com/questions/181304/what-is-infinity-divided-by-infinity).
>
> Good point, I agree this should return an error. We also need to
> properly handle multiplication and division of infinite intervals by
> float8 'nan'. My patch is returning an infinite interval, but it should
> be returning an error. I'll upload a new patch shortly.
>
> - Joe

Attached is the patch to handle these scenarios. Apparently dividing by
NaN is currently broken:
postgres=# SELECT INTERVAL '1 day' / float8 'nan';
?column?
---------------------------------------------------
-178956970 years -8 mons -2562047788:00:54.775808
(1 row)

This patch will fix the issue, but we may want a separate patch that
handles this specific, existing issue. Any thoughts?

- Joe