Cool! I pushed the first patch after polishing it a little bit, so here is a rebased version of the second patch, in which I modified the ForeignPath and CustomPath cases in reparameterize_path_by_child() to reflect the new members fdw_restrictinfo and custom_restrictinfo, for safety, and tweaked a comment a bit.
Hmm, it seems that ForeignPath for a foreign join does not support parameterized paths for now, as in postgresGetForeignJoinPaths() we have this check:
/* * This code does not work for joins with lateral references, since those * must have parameterized paths, which we don't generate yet. */ if (!bms_is_empty(joinrel->lateral_relids)) return;
And in create_foreign_join_path() we just set the path.param_info to NULL.
pathnode->path.param_info = NULL; /* XXX see above */
So I doubt that it's necessary to adjust fdw_restrictinfo in reparameterize_path_by_child, because it seems to me that fdw_restrictinfo must be empty there. Maybe we can add an Assert there as below:
- ADJUST_CHILD_ATTRS(fpath->fdw_restrictinfo); + + /* + * Parameterized foreign joins are not supported. So this + * ForeignPath cannot be a foreign join and fdw_restrictinfo + * must be empty. + */ + Assert(fpath->fdw_restrictinfo == NIL);
That being said, it's also no harm to handle fdw_restrictinfo in reparameterize_path_by_child as the patch does. So I'm OK we do that for safety.
