Andrew Tipton <andrew.t.tipton@gmail.com> writes:
> At this point I'm a bit lost -- while pg_amop.h has plenty of examples
> of crosstype comparison operators for btree index methods, there are
> none for GiST. Is GiST somehow a special case in this regard?
AFAIR, GIST doesn't use the concept of a crosstype opclass entry.
It only works with primary opclass entries. You have to set both
amproclefttype and amprocrighttype to the datatype of the indexable
column, regardless of what the other argument actually is.
(I think this implies that you can't have more than one consistent
function per opclass, which means you have to do whatever it is you
have in mind by patching the existing consistent function, not adding
another one alongside it.)
regards, tom lane