John A Meinel <john(at)arbash-meinel(dot)com> writes:
> Now if you created the index on b(r,c), then it would have a much better
> idea of how selective that would be. At the very least, it could index
> on (r,c) rather than indexing on (r) and filtering by (c).
There has been some discussion of adding functionality like this but afaik no
version of Postgres actually does this yet.
Adding the index may still help though.
--
greg