Angela Maduko <ifymaduko(at)gmail(dot)com> writes:
> I am trying to write a join selectivity function for a user defined
> operator. The available documentation does not exactly specify how to
> go about this. Can anyone shed more light on this?
There isn't a lot of documentation, no :-(. I would suggest looking
over the existing selectivity functions (in
src/backend/utils/adt/selfuncs.c). If you have specific questions,
pghackers is probably the best place to ask them.
regards, tom lane