Hi, On Tue, Aug 15, 2023 at 11:02 PM Önder Kalacı <onderkal...@gmail.com> wrote: > The commit[1] seems to break some queries in Citus[2], which is an extension > which relies on set_join_pathlist_hook. > > Although the comment says /*Finally, give extensions a chance to manipulate > the path list.*/ we use it to extract lots of information about the joins > and do the planning based on the information. > > Now, for some joins where consider_join_pushdown=false, we cannot get the > information that we used to get, which prevents doing distributed planning > for certain queries. > > We wonder if it is possible to allow extensions to access the join info under > all circumstances, as it used to be? Basically, removing the additional check: > > diff --git a/src/backend/optimizer/path/joinpath.c > b/src/backend/optimizer/path/joinpath.c > index 03b3185984..080e76cbe9 100644 > --- a/src/backend/optimizer/path/joinpath.c > +++ b/src/backend/optimizer/path/joinpath.c > @@ -349,8 +349,7 @@ add_paths_to_joinrel(PlannerInfo *root, > /* > * 6. Finally, give extensions a chance to manipulate the path list. > */ > - if (set_join_pathlist_hook && > - consider_join_pushdown) > + if (set_join_pathlist_hook) > set_join_pathlist_hook(root, joinrel, outerrel, innerrel, > jointype, &extra);
Maybe we could do so by leaving to extensions the decision whether they replace joins with pseudoconstant clauses, but I am not sure that that is a good idea, because that would require the authors to modify and recompile their extensions to fix the issue... So I fixed the core side. I am not familiar with the Citus extension, but such pseudoconstant clauses are handled within the Citus extension? Thanks for the report! Best regards, Etsuro Fujita