Tweak a couple of planner APIs to save recalculating join relids.

Discussion: https://postgr.es/m/f8128b11-c5bf-3539-48cd-234178b2314d@proxel.se

src/backend/optimizer/path/costsize.c

@@ -4023,6 +4023,7 @@ get_restriction_qual_cost(PlannerInfo *root, RelOptInfo *baserel,
  * them to all the join cost estimation functions.
  *
  * Input parameters:
+ *	joinrel: join relation under consideration
  *	outerrel: outer relation under consideration
  *	innerrel: inner relation under consideration
  *	jointype: if not JOIN_SEMI or JOIN_ANTI, we assume it's inner_unique
@@ -4033,6 +4034,7 @@ get_restriction_qual_cost(PlannerInfo *root, RelOptInfo *baserel,
  */
 void
 compute_semi_anti_join_factors(PlannerInfo *root,
+							   RelOptInfo *joinrel,
 							   RelOptInfo *outerrel,
 							   RelOptInfo *innerrel,
 							   JoinType jointype,
@@ -4056,14 +4058,12 @@ compute_semi_anti_join_factors(PlannerInfo *root,
 	 */
 	if (IS_OUTER_JOIN(jointype))
 	{
-		Relids		joinrelids = bms_union(outerrel->relids, innerrel->relids);
-
 		joinquals = NIL;
 		foreach(l, restrictlist)
 		{
 			RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 
-			if (!RINFO_IS_PUSHED_DOWN(rinfo, joinrelids))
+			if (!RINFO_IS_PUSHED_DOWN(rinfo, joinrel->relids))
 				joinquals = lappend(joinquals, rinfo);
 		}
 	}

src/backend/optimizer/path/joinpath.c

@@ -171,6 +171,7 @@ add_paths_to_joinrel(PlannerInfo *root,
 			break;
 		case JOIN_UNIQUE_OUTER:
 			extra.inner_unique = innerrel_is_unique(root,
+													joinrel->relids,
 													outerrel->relids,
 													innerrel,
 													JOIN_INNER,
@@ -179,6 +180,7 @@ add_paths_to_joinrel(PlannerInfo *root,
 			break;
 		default:
 			extra.inner_unique = innerrel_is_unique(root,
+													joinrel->relids,
 													outerrel->relids,
 													innerrel,
 													jointype,
@@ -207,7 +209,7 @@ add_paths_to_joinrel(PlannerInfo *root,
 	 * for cost estimation.  These will be the same for all paths.
 	 */
 	if (jointype == JOIN_SEMI || jointype == JOIN_ANTI || extra.inner_unique)
-		compute_semi_anti_join_factors(root, outerrel, innerrel,
+		compute_semi_anti_join_factors(root, joinrel, outerrel, innerrel,
 									   jointype, sjinfo, restrictlist,
 									   &extra.semifactors);
 

src/backend/optimizer/plan/analyzejoins.c

@@ -42,6 +42,7 @@ static bool rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel,
 					List *clause_list);
 static Oid	distinct_col_search(int colno, List *colnos, List *opids);
 static bool is_innerrel_unique_for(PlannerInfo *root,
+					   Relids joinrelids,
 					   Relids outerrelids,
 					   RelOptInfo *innerrel,
 					   JoinType jointype,
@@ -565,7 +566,8 @@ reduce_unique_semijoins(PlannerInfo *root)
 						innerrel->joininfo);
 
 		/* Test whether the innerrel is unique for those clauses. */
-		if (!innerrel_is_unique(root, sjinfo->min_lefthand, innerrel,
+		if (!innerrel_is_unique(root,
+								joinrelids, sjinfo->min_lefthand, innerrel,
 								JOIN_SEMI, restrictlist, true))
 			continue;
 
@@ -947,7 +949,8 @@ distinct_col_search(int colno, List *colnos, List *opids)
  *
  * We need an actual RelOptInfo for the innerrel, but it's sufficient to
  * identify the outerrel by its Relids.  This asymmetry supports use of this
- * function before joinrels have been built.
+ * function before joinrels have been built.  (The caller is expected to
+ * also supply the joinrelids, just to save recalculating that.)
  *
  * The proof must be made based only on clauses that will be "joinquals"
  * rather than "otherquals" at execution.  For an inner join there's no
@@ -966,6 +969,7 @@ distinct_col_search(int colno, List *colnos, List *opids)
  */
 bool
 innerrel_is_unique(PlannerInfo *root,
+				   Relids joinrelids,
 				   Relids outerrelids,
 				   RelOptInfo *innerrel,
 				   JoinType jointype,
@@ -1014,7 +1018,7 @@ innerrel_is_unique(PlannerInfo *root,
 	}
 
 	/* No cached information, so try to make the proof. */
-	if (is_innerrel_unique_for(root, outerrelids, innerrel,
+	if (is_innerrel_unique_for(root, joinrelids, outerrelids, innerrel,
 							   jointype, restrictlist))
 	{
 		/*
@@ -1073,12 +1077,12 @@ innerrel_is_unique(PlannerInfo *root,
  */
 static bool
 is_innerrel_unique_for(PlannerInfo *root,
+					   Relids joinrelids,
 					   Relids outerrelids,
 					   RelOptInfo *innerrel,
 					   JoinType jointype,
 					   List *restrictlist)
 {
-	Relids		joinrelids = bms_union(outerrelids, innerrel->relids);
 	List	   *clause_list = NIL;
 	ListCell   *lc;
 

src/include/optimizer/cost.h

@@ -166,6 +166,7 @@ extern void cost_subplan(PlannerInfo *root, SubPlan *subplan, Plan *plan);
 extern void cost_qual_eval(QualCost *cost, List *quals, PlannerInfo *root);
 extern void cost_qual_eval_node(QualCost *cost, Node *qual, PlannerInfo *root);
 extern void compute_semi_anti_join_factors(PlannerInfo *root,
+							   RelOptInfo *joinrel,
 							   RelOptInfo *outerrel,
 							   RelOptInfo *innerrel,
 							   JoinType jointype,

src/include/optimizer/planmain.h

@@ -108,7 +108,7 @@ extern void reduce_unique_semijoins(PlannerInfo *root);
 extern bool query_supports_distinctness(Query *query);
 extern bool query_is_distinct_for(Query *query, List *colnos, List *opids);
 extern bool innerrel_is_unique(PlannerInfo *root,
-				   Relids outerrelids, RelOptInfo *innerrel,
+				   Relids joinrelids, Relids outerrelids, RelOptInfo *innerrel,
 				   JoinType jointype, List *restrictlist, bool force_cache);
 
 /*