2011/1/6 Jeff Davis <pgsql@j-davis.com>:
> Even if add and subtract were associated with a range type, there's no
> way to tell which range type to pick given the window function syntax
> (multiple range types could be defined over the same subtype).
>
> I think the interface question should be addressed more directly with a
> "type interfaces" patch.
I agree the current canonical approach fits range type's demand, and
I'm inclined that the type interface discussion is another point.
IIRC, Robert Haas originally began to propose the idea of type
interface to get together three of KNN-GIST, range type and window
frame issue. For KNN-GIST, it was committed by extending pg_amop
without considering others and range type will be as well. Not getting
them together might be the answer.
Regards,
--
Hitoshi Harada