2 files changed, 41 insertions, 0 deletions
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 07f5aad5ea..eea8978fad 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -4982,6 +4982,32 @@ select id from a where id in (
          ->  Seq Scan on b
 (5 rows)
 
+-- check optimization with oddly-nested outer joins
+explain (costs off)
+select a1.id from
+  (a a1 left join a a2 on true)
+  left join
+  (a a3 left join a a4 on a3.id = a4.id)
+  on a2.id = a3.id;
+          QUERY PLAN          
+------------------------------
+ Nested Loop Left Join
+   ->  Seq Scan on a a1
+   ->  Materialize
+         ->  Seq Scan on a a2
+(4 rows)
+
+explain (costs off)
+select a1.id from
+  (a a1 left join a a2 on a1.id = a2.id)
+  left join
+  (a a3 left join a a4 on a3.id = a4.id)
+  on a2.id = a3.id;
+    QUERY PLAN    
+------------------
+ Seq Scan on a a1
+(1 row)
+
 -- check that join removal works for a left join when joining a subquery
 -- that is guaranteed to be unique by its GROUP BY clause
 explain (costs off)
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index 7157b5cccc..9d20b88d71 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1770,6 +1770,21 @@ select id from a where id in (
 	select b.id from b left join c on b.id = c.id
 );
 
+-- check optimization with oddly-nested outer joins
+explain (costs off)
+select a1.id from
+  (a a1 left join a a2 on true)
+  left join
+  (a a3 left join a a4 on a3.id = a4.id)
+  on a2.id = a3.id;
+
+explain (costs off)
+select a1.id from
+  (a a1 left join a a2 on a1.id = a2.id)
+  left join
+  (a a3 left join a a4 on a3.id = a4.id)
+  on a2.id = a3.id;
+
 -- check that join removal works for a left join when joining a subquery
 -- that is guaranteed to be unique by its GROUP BY clause
 explain (costs off)