Re: Time span conversion function

Brendan Jurd <blakjak@blakjak.sytes.net> writes:
> Of course, it would be possible to create a shorthand version of the 
> function which expects (text, interval), and passes directly to 
> time_span($1, now(), $2).

This bothers me a bit.  That essentially says that (text, interval)
has a hidden instability: the results depend on when you execute it.

If we allow this form, it should be restricted to only those units
(values of the text parameter) for which the result would *not*
depend on now().
        regards, tom lane