Re: Distinct types

Peter Eisentraut <peter_e@gmx.net> writes:
> On Friday 31 October 2008 17:01:05 Kevin Grittner wrote:
>> (1)  Can you compare a literal of the base type?

> No, unless you create additional casts or operators.

>> (2)  Can you explicitly cast to the base type?

> There is an implicit AS ASSIGNMENT cast between the base type and the distinct 
> type in each direction.

Hmm ... so out-of-the-box, a distinct type would have no applicable
functions/operators whatsoever.  You couldn't even create an index on
it.  This seems a bit too impoverished to be useful.  And given the
known gotchas with creating functions/operators on domains, I'm not
convinced someone could fix the problem by creating specialized
functions for their distinct type.  Even if they could fix it,
having to set up a custom btree opclass in order to have an index
seems to take this out of the "easy to use" category.
        regards, tom lane