Re: WIP: RangeTypes

Jeff Davis <pgsql@j-davis.com> writes:
> On Fri, 2011-01-28 at 21:52 +0000, Thom Brown wrote:
> Also, if I try the same, but with a different name for the type, I get
> the same error.  Why does that restriction exist?  Can't you have
> types which happen to use the exact same subtype?

> At first, that's how I designed it. Then, I realized that the type
> system needs to know the range type from the element type in order for
> something like ANYRANGE to work.

That seems like a fairly bad restriction.  In a datatype with multiple
useful sort orderings, it'd be desirable to be able to create a range
type for each such ordering, no?  I'd be inclined to think of a range
type as being defined by element type plus a btree opfamily.  Maybe it'd
be okay to insist on that combination as being unique.
        regards, tom lane