Jan Urbański <j.urbanski@students.mimuw.edu.pl> writes:
> Same thing for GROUP BY.
Yeah. The GROUP BY case is even more annoying, because we *have* the
planner/executor infrastructure to do it via hashing; but the parser
barfs immediately if there is not btree opclass support for the type.
I'm not sure how to fix the parser and the parsetree representation
to be agnostic about hash versus sort implementations --- any thoughts?
> ... One last remark: unless something is done about
> it in 8.4, maybe it is worthwhile to change the error message (which
> clearly confused Nick) and add some documentation about why you can't
> use DISTINCT with types without a btree index opclass?
IIRC, the error message is correct for some other cases, so it might be
hard to fix it without taking two steps backward overall. But feel free
to take a look if you want to. Nuthin wrong with more documentation
either ...
regards, tom lane