3 files changed, 59 insertions, 0 deletions
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 14521728c63..ce57dfa7cde 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -3256,6 +3256,7 @@ remove_result_refs(PlannerInfo *root, int varno, Node *newjtloc)
 		subrelids = get_relids_in_jointree(newjtloc, false);
 		Assert(!bms_is_empty(subrelids));
 		substitute_phv_relids((Node *) root->parse, varno, subrelids);
+		fix_append_rel_relids(root->append_rel_list, varno, subrelids);
 	}
 
 	/*
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index a1180417319..b0533a71955 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -3333,6 +3333,42 @@ select * from
  1 | 2 | 2
 (1 row)
 
+-- Test proper handling of appendrel PHVs during useless-RTE removal
+explain (costs off)
+select * from
+  (select 0 as z) as t1
+  left join
+  (select true as a) as t2
+  on true,
+  lateral (select true as b
+           union all
+           select a as b) as t3
+where b;
+              QUERY PLAN               
+---------------------------------------
+ Nested Loop
+   ->  Result
+   ->  Append
+         ->  Result
+         ->  Result
+               One-Time Filter: (true)
+(6 rows)
+
+select * from
+  (select 0 as z) as t1
+  left join
+  (select true as a) as t2
+  on true,
+  lateral (select true as b
+           union all
+           select a as b) as t3
+where b;
+ z | a | b 
+---+---+---
+ 0 | t | t
+ 0 | t | t
+(2 rows)
+
 --
 -- test inlining of immutable functions
 --
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index 4de24c19040..00720b629a6 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1056,6 +1056,28 @@ select * from
   (select 1 as x) ss1 left join (select 2 as y) ss2 on (true),
   lateral (select ss2.y as z limit 1) ss3;
 
+-- Test proper handling of appendrel PHVs during useless-RTE removal
+explain (costs off)
+select * from
+  (select 0 as z) as t1
+  left join
+  (select true as a) as t2
+  on true,
+  lateral (select true as b
+           union all
+           select a as b) as t3
+where b;
+
+select * from
+  (select 0 as z) as t1
+  left join
+  (select true as a) as t2
+  on true,
+  lateral (select true as b
+           union all
+           select a as b) as t3
+where b;
+
 --
 -- test inlining of immutable functions
 --