Re: Documentation of return values of range functions lower and upper

On Thu, Nov 2, 2023 at 08:56:13AM +0100, Laurenz Albe wrote:
> On Wed, 2023-11-01 at 18:03 -0400, Bruce Momjian wrote:
> > On Wed, Nov 1, 2023 at 09:40:43PM +0100, Laurenz Albe wrote:
> > > > Yes, I agree this documentation needs help.
> > > >
> > > > For upper/lower(), it is clear that the documentation is better saying
> > > > "unspecified" rather than infinite. The fact that upper/lower_inf()
> > > > returns false for +/-Infinity is quite odd, but should at least be
> > > > documented.
> > > >
> > > > Patch attached. It is odd that +Infinity (vs. Infinity) wasn't
> > > > supported for datetime input until PG 16, but I think we have to say
> > > > +/-infinity vs (blank)/-Infinity.
> > > >
> > > > Patch attached.
> > >
> > > I am unhappy with "unspecified". A NULL value as upper or lower bound has a very
> > > specific meaning, namely that the range is unbounded in that direction. This is
> > > a bit confusing, since NULL is typically used for unknown or undefined values.
> > >
> > > I think it would be better to say "returns NULL if the range is empty or unbounded"
> > > and "is the range unbounded on the upper end?".
> >
> > I had to go with "Is the multirange's lower bound unbounded?" because
> > the surrounding items use that sentence structure. Patch attached.
>
> Better, though "Is the range's upper bound unbounded?" makes me cringe.

Oh, yeah, totally cringe, me too. :-)

> It is not the bound that is bounded or not, but the range.
>
> How about "Is the range unbounded at the upper end?" or "Does the range
> have no upper bound?"

I used your "end" idea to modify the patch, attached.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

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