From dee15ecc2aa6d79bffea85f4c047dc50836751a8 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Wed, 30 Aug 2023 14:58:06 +0900
Subject: [PATCH] Fix handling of outer-join relids

find_join_hint() calculates the join level using joinrelids which
is a bitmapset of relations.  However, since the upstream commit
2489d76c introduced in 16, it is possible that these include outer-join
relids, something that pg_hint_plan cannot digest because it expects
only case relations.

This commit filters out any outer-join relids from the lists of relids
considered during the join calculations.  This could cause crashes
because of corrupted relids lists.

There may be a smarter way to fix that, but this is proving to be good
enough for now.

Per issue #139.

Reported-by: Michael Paquier
Author: Masahiro Ikeda
Backpatch-through: 16
---
 expected/pg_hint_plan.out | 16 ++++++++++++++++
 pg_hint_plan.c            | 20 ++++++++++++++++++++
 sql/pg_hint_plan.sql      |  5 +++++
 3 files changed, 41 insertions(+)

diff --git a/expected/pg_hint_plan.out b/expected/pg_hint_plan.out
index 8ef19f85..2c8d9f5b 100644
--- a/expected/pg_hint_plan.out
+++ b/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 and outer-join relids
+/*+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;
diff --git a/pg_hint_plan.c b/pg_hint_plan.c
index 2d4421fa..580001d1 100644
--- a/pg_hint_plan.c
+++ b/pg_hint_plan.c
@@ -4177,6 +4177,12 @@ OuterInnerJoinCreate(OuterInnerRels *outer_inner, LeadingHint *leading_hint,
 
 	join_relids = bms_add_members(outer_relids, inner_relids);
 
+	/*
+	 * join_relids may include outer-join relids since PostgreSQL 16, so
+	 * filter them out as hints can only handle base relations.
+	 */
+	join_relids = bms_intersect(join_relids, root->all_baserels);
+
 	if (bms_num_members(join_relids) > nbaserel)
 		return join_relids;
 
@@ -4530,6 +4536,13 @@ make_join_rel_wrapper(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
 	int				save_nestlevel;
 
 	joinrelids = bms_union(rel1->relids, rel2->relids);
+
+	/*
+	 * joinrelids may include outer-join relids since PostgreSQL 16, so
+	 * filter them out as hints can only handle base relations.
+	 */
+	joinrelids = bms_intersect(joinrelids, root->all_baserels);
+
 	join_hint = find_join_hint(joinrelids);
 	memoize_hint = find_memoize_hint(joinrelids);
 	bms_free(joinrelids);
@@ -4597,6 +4610,13 @@ add_paths_to_joinrel_wrapper(PlannerInfo *root,
 	int				save_nestlevel;
 
 	joinrelids = bms_union(outerrel->relids, innerrel->relids);
+
+	/*
+	 * joinrelids may include outer-join relids since PostgreSQL 16, so
+	 * filter them out as hints can only handle base relations.
+	 */
+	joinrelids = bms_intersect(joinrelids, root->all_baserels);
+
 	join_hint = find_join_hint(joinrelids);
 	memoize_hint = find_memoize_hint(joinrelids);
 	bms_free(joinrelids);
diff --git a/sql/pg_hint_plan.sql b/sql/pg_hint_plan.sql
index 5e12ecce..9fab9031 100644
--- a/sql/pg_hint_plan.sql
+++ b/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 and outer-join relids
+/*+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;