On Fri, Apr 9, 2010 at 7:18 PM, Nathan Boley <npboley@gmail.com> wrote:
>> The advantage of specifying a + and a - in the type interface is that
>> the unit definition can then be specified as part of the type
>> declaration itself. So you can do:
>>
>> CREATE TYPE ts_sec AS RANGE OVER timestamp (UNIT = '1s');
>> CREATE TYPE ts_min AS RANGE OVER timestamp (UNIT = '1m');
>>
>> All of the stuff about defining + and - is hidden from the user - it's
>> part of the type interface, which is pre-created.
>
> The disadvantage is that it does not permit irregularly spaced units.
True. The only types I can think of that have irregularly spaced
units would be things based on floating points, and I was assuming
that people would only want continuous intervals on those. If someone
really wants to be able to deduce that [1.0,3.0) = [1.0,3.0-epsilon),
then we need a different design. But I find it hard to believe that's
very useful. Maybe you feel otherwise?
...Robert