Do assorted mop-up in the planner.

Remove RestrictInfo.nullable_relids, along with a good deal of
infrastructure that calculated it.  One use-case for it was in
join_clause_is_movable_to, but we can now replace that usage with
a check to see if the clause's relids include any outer join
that can null the target relation.  The other use-case was in
join_clause_is_movable_into, but that test can just be dropped
entirely now that the clause's relids include outer joins.
Furthermore, join_clause_is_movable_into should now be
accurate enough that it will accept anything returned by
generate_join_implied_equalities, so we can restore the Assert
that was diked out in commit 95f4e59c3.

Remove the outerjoin_delayed mechanism.  We needed this before to
prevent quals from getting evaluated below outer joins that should
null some of their vars.  Now that we consider varnullingrels while
placing quals, that's taken care of automatically, so throw the
whole thing away.

Teach remove_useless_result_rtes to also remove useless FromExprs.
Having done that, the delay_upper_joins flag serves no purpose any
more and we can remove it, largely reverting 11086f2f2.

Use constant TRUE for "dummy" clauses when throwing back outer joins.
This improves on a hack I introduced in commit 6a6522529.  If we
have a left-join clause l.x = r.y, and a WHERE clause l.x = constant,
we generate r.y = constant and then don't really have a need for the
join clause.  But we must throw the join clause back anyway after
marking it redundant, so that the join search heuristics won't think
this is a clauseless join and avoid it.  That was a kluge introduced
under time pressure, and after looking at it I thought of a better
way: let's just introduce constant-TRUE "join clauses" instead,
and get rid of them at the end.  This improves the generated plans for
such cases by not having to test a redundant join clause.  We can also
get rid of the ugly hack used to mark such clauses as redundant for
selectivity estimation.

Patch by me; thanks to Richard Guo for review.

Discussion: https://postgr.es/m/830269.1656693747@sss.pgh.pa.us

4 files changed, 3 insertions, 10 deletions

diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 9b38627efd8..1b02a1dc087 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -128,7 +128,6 @@ extern Expr *canonicalize_ec_expression(Expr *expr,
 extern void reconsider_outer_join_clauses(PlannerInfo *root);
 extern EquivalenceClass *get_eclass_for_sort_expr(PlannerInfo *root,
 												  Expr *expr,
-												  Relids nullable_relids,
 												  List *opfamilies,
 												  Oid opcintype,
 												  Oid collation,
@@ -216,7 +215,7 @@ extern List *build_index_pathkeys(PlannerInfo *root, IndexOptInfo *index,
 extern List *build_partition_pathkeys(PlannerInfo *root, RelOptInfo *partrel,
 									  ScanDirection scandir, bool *partialkeys);
 extern List *build_expression_pathkey(PlannerInfo *root, Expr *expr,
-									  Relids nullable_relids, Oid opno,
+									  Oid opno,
 									  Relids rel, bool create_it);
 extern List *convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel,
 									   List *subquery_pathkeys,
diff --git a/src/include/optimizer/placeholder.h b/src/include/optimizer/placeholder.h
index 31e1578e822..acb9cf9f05c 100644
--- a/src/include/optimizer/placeholder.h
+++ b/src/include/optimizer/placeholder.h
@@ -22,8 +22,6 @@ extern PlaceHolderVar *make_placeholder_expr(PlannerInfo *root, Expr *expr,
 extern PlaceHolderInfo *find_placeholder_info(PlannerInfo *root,
 											  PlaceHolderVar *phv);
 extern void find_placeholders_in_jointree(PlannerInfo *root);
-extern void update_placeholder_eval_levels(PlannerInfo *root,
-										   SpecialJoinInfo *new_sjinfo);
 extern void fix_placeholder_input_needed_levels(PlannerInfo *root);
 extern void add_placeholders_to_base_rels(PlannerInfo *root);
 extern void add_placeholders_to_joinrel(PlannerInfo *root, RelOptInfo *joinrel,
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 95ecefdadec..3e6e60f5498 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -83,7 +83,6 @@ extern RestrictInfo *process_implied_equality(PlannerInfo *root,
 											  Expr *item1,
 											  Expr *item2,
 											  Relids qualscope,
-											  Relids nullable_relids,
 											  Index security_level,
 											  bool below_outer_join,
 											  bool both_const);
@@ -93,7 +92,6 @@ extern RestrictInfo *build_implied_join_equality(PlannerInfo *root,
 												 Expr *item1,
 												 Expr *item2,
 												 Relids qualscope,
-												 Relids nullable_relids,
 												 Index security_level);
 extern void match_foreign_keys_to_quals(PlannerInfo *root);
 
diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h
index c79bb420e4e..c9e30776c52 100644
--- a/src/include/optimizer/restrictinfo.h
+++ b/src/include/optimizer/restrictinfo.h
@@ -19,17 +19,15 @@
 
 /* Convenience macro for the common case of a valid-everywhere qual */
 #define make_simple_restrictinfo(root, clause)  \
-	make_restrictinfo(root, clause, true, false, false, 0, NULL, NULL, NULL)
+	make_restrictinfo(root, clause, true, false, 0, NULL, NULL)
 
 extern RestrictInfo *make_restrictinfo(PlannerInfo *root,
 									   Expr *clause,
 									   bool is_pushed_down,
-									   bool outerjoin_delayed,
 									   bool pseudoconstant,
 									   Index security_level,
 									   Relids required_relids,
-									   Relids outer_relids,
-									   Relids nullable_relids);
+									   Relids outer_relids);
 extern RestrictInfo *commute_restrictinfo(RestrictInfo *rinfo, Oid comm_op);
 extern bool restriction_is_or_clause(RestrictInfo *restrictinfo);
 extern bool restriction_is_securely_promotable(RestrictInfo *restrictinfo,