On Wed, Apr 24, 2019 at 1:15 AM Tom Lane <t...@sss.pgh.pa.us> wrote: > Ibrar Ahmed <ibrar.ah...@gmail.com> writes: > > I am working on an FDW where the database does not support any operator > > other than "=" in JOIN condition. Some queries are genrating the plan > with > > JOIN having "<" operator. How and at what stage I can stop FDW to not > make > > such a plan. Here is my sample query. > > What exactly do you think should happen instead? You can't just tell > users not to ask such a query. (Well, you can try, but they'll probably > go looking for a less broken FDW.) > > I know that.
> If what you really mean is you don't want to generate pushed-down > foreign join paths containing non-equality conditions, the answer is > to just not do that. That'd be the FDW's own fault, not that of > the core planner, if it creates a path representing a join it > can't actually implement. You'll end up running the join locally, > which might not be great, but if you have no other alternative > then that's what you gotta do. > > Yes, that's what I am thinking. In case of non-equality condition join them locally is the only solution. I was just confirming. > If what you mean is you don't know how to inspect the join quals > to see if you can implement them, take a look at postgres_fdw > to see how it handles the same issue. > > I really don't know postgres_fdw have the same issue, but yes postgres_fdw is always my starting point. > regards, tom lane > -- Ibrar Ahmed
