Re: interval / interval -> double operator

On 5/17/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> "Andrew Hammond" <andrew(dot)george(dot)hammond(at)gmail(dot)com> writes:
> > On 5/17/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> What are the grounds for defining it that way rather than some other
> >> way?
>
> > The only alternative that came to mind when I wrote it was using a
> numeric
> > instead of float.
>
> No, I'm wondering what's the justification for smashing it to a single
> number at all, when the inputs are three-field values. Interval divided
> by float doesn't produce just a float, for example.
>

I think I see what you're getting at here. '1 month' / '1 day' could return
a number of reasonable values depending on how many days are in the month
(28 to 31) and on how many hours are in a day (generally 24, but can be 23
or 25 for DST adjustments). The definition above simply assumes that
EXTRACT(epoch...) does the Right Thing. Hmmm. I'm at a loss for the right
way to solve this. It seems very reasonable to want to divide intervals by
intervals (how many nanocenturies in a fortnight?), but I'm at a loss for
how to do that correctly. I'll read the code from EXTRACT(epoch...) and see
what happening there.

Andrew