On Wed, 11 Aug 2021 at 16:51, David Rowley <dgrowle...@gmail.com> wrote: > The patch is just some plumbing work to connect all the correct paths > up to make it work. It's all fairly trivial.
I looked at this patch again and realise that it could be done a bit better. For example, the previous version set the distinct_rel's FDW fields twice, once when making the serial paths and once when finalizing the partial paths. I've now added two new functions; create_final_distinct_paths and create_partial_distinct_paths. The responsibility of create_distinct_paths has changed. Instead of it creating the non-parallel DISTINCT paths, it calls the two new functions and also takes charge of calling the create_upper_paths_hook for UPPERREL_DISTINCT plus the FDW GetForeignUpperPaths() call. I think this is nicer as I'd previously added a new parameter to create_distinct_paths() so I could tell it not to call the hook as I didn't want to call that twice on the same relation as it would no doubt result in some plugin just creating the same paths again. I've also changed my mind about the previous choice I'd made not to call GetForeignUpperPaths for the UPPERREL_PARTIAL_DISTINCT. I now think that's ok. I think this is a fairly trivial patch that just does a bit of wiring up of paths. Unless anyone has anything to say about it in the next few days, I'll be looking at it again with intensions to push it. David
