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@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Only you can decide what is important to you.