On Tue, Jun 4, 2024 at 6:51 PM Tender Wang <tndrwang@gmail.com> wrote: > Yeah, Richard commented the v1 patch about JOIN_UNIQUE_INNER in [1] > > * I think we should not consider materializing the cheapest inner path > if we're doing JOIN_UNIQUE_INNER, because in this case we have to > unique-ify the inner path. > > We don't consider material inner path if jointype is JOIN_UNIQUE_INNER in match_unsorted_order(). > So here is as same logic as match_unsorted_order(). I added comments to explain why.
I looked through the v4 patch and found an issue. For the plan diff:
+ -> Nested Loop + -> Parallel Seq Scan on prt1_p1 t1_1 + -> Materialize + -> Sample Scan on prt1_p1 t2_1 + Sampling: system (t1_1.a) REPEATABLE (t1_1.b) + Filter: (t1_1.a = a)
This does not seem correct to me. The inner path is parameterized by the outer rel, in which case it does not make sense to add a Materialize node on top of it.
Yeah, you're right.
I updated the patch to include a check in consider_parallel_nestloop ensuring that inner_cheapest_total is not parameterized by outerrel before materializing it. I also tweaked the comments, test cases and commit message.
Thanks for the work. Now it looks better.
I have changed the status from "need review" to "ready for commiters" on the commitfest.