[Poc] Fix handling of joinrelids ossc-db#139

find_join_hint() calculates the join level using joinrelids which
is a bitmapset of relations within the join with the assumption that
the relids has only base relations.

But, relids became to have outer-join relids with PostgreSQL
commit (2489d76c). So, the calculation logic became wrong and
crash on some condition.

The commit fixes the logic to calculate joinrelids to consider
only base relations.

This patch is for PoC. I think we need to think the following.

* Is the test enough and stable?
* Don't we need to change OuterInnerJoinCreate() and
  transform_join_hints which call find_join_hint()?

expected/pg_hint_plan.out

@@ -9131,6 +9131,22 @@ set max_parallel_workers_per_gather to DEFAULT;
          ->  Seq Scan on t3  (cost=xxx..xxx rows=100 width=xxx)
 
 \! rm results/pg_hint_plan.tmpout
+-- query with join RTE
+/*+Leading(ft_1 ft_2 t1)*/
+SELECT relname, seq_scan > 0 as seq_scan, idx_scan > 0 as idx_scan
+FROM pg_stat_user_tables WHERE schemaname = 'public' AND relname = 't1';
+LOG:  pg_hint_plan:
+used hint:
+not used hint:
+Leading(ft_1 ft_2 t1)
+duplication hint:
+error hint:
+
+ relname | seq_scan | idx_scan 
+---------+----------+----------
+ t1      | f        | f
+(1 row)
+
 -- hint error level
 set client_min_messages to 'DEBUG1';
 /*+ SeqScan( */ SELECT 1;

pg_hint_plan.c

@@ -4530,6 +4530,7 @@ make_join_rel_wrapper(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
 	int				save_nestlevel;
 
 	joinrelids = bms_union(rel1->relids, rel2->relids);
+	joinrelids = bms_intersect(joinrelids, root->all_baserels);
 	join_hint = find_join_hint(joinrelids);
 	memoize_hint = find_memoize_hint(joinrelids);
 	bms_free(joinrelids);
@@ -4597,6 +4598,7 @@ add_paths_to_joinrel_wrapper(PlannerInfo *root,
 	int				save_nestlevel;
 
 	joinrelids = bms_union(outerrel->relids, innerrel->relids);
+	joinrelids = bms_intersect(joinrelids, root->all_baserels);
 	join_hint = find_join_hint(joinrelids);
 	memoize_hint = find_memoize_hint(joinrelids);
 	bms_free(joinrelids);

sql/pg_hint_plan.sql

@@ -1159,6 +1159,11 @@ set max_parallel_workers_per_gather to DEFAULT;
 \! sql/maskout.sh results/pg_hint_plan.tmpout
 \! rm results/pg_hint_plan.tmpout
 
+-- query with join RTE
+/*+Leading(ft_1 ft_2 t1)*/
+SELECT relname, seq_scan > 0 as seq_scan, idx_scan > 0 as idx_scan
+FROM pg_stat_user_tables WHERE schemaname = 'public' AND relname = 't1';
+
 -- hint error level
 set client_min_messages to 'DEBUG1';
 /*+ SeqScan( */ SELECT 1;