Re: Range Types: << >> -|- ops vs empty range

Jeff Davis <pgsql@j-davis.com> wrote:
 
> ">>" means "strictly right of"
> "<<" means "strictly left of"
> "-|-" means "adjacent" (touching but not overlapping)
> 
> I'm open to suggestion about how those behave with empty ranges.
 
OK, that still leaves a lot to the imagination, though.  To try to
clarify in *my* mind:
 
"empty range"
=============
Zero length?
  If so, is it fixed at some point, but empty?
    '(x,x)'?
    '[x,x)'?
 
Is it everything?
  '[-inf,+inf]'?
 
Is it really meaningfully distinct from NULL?
 
Where do you see it being useful?
 
-Kevin