diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 9b69a8c122..b901d7299f 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -2650,6 +2650,69 @@ WHERE d.f1 IS NULL;
  9999
 (3 rows)
 
+--
+-- basic semijoin and antijoin recognition tests
+--
+explain (costs off)
+select a.* from tenk1 a
+where unique1 in (select unique2 from tenk1 b);
+                         QUERY PLAN                         
+------------------------------------------------------------
+ Hash Semi Join
+   Hash Cond: (a.unique1 = b.unique2)
+   ->  Seq Scan on tenk1 a
+   ->  Hash
+         ->  Index Only Scan using tenk1_unique2 on tenk1 b
+(5 rows)
+
+-- sadly, this is not an antijoin
+explain (costs off)
+select a.* from tenk1 a
+where unique1 not in (select unique2 from tenk1 b);
+                       QUERY PLAN                       
+--------------------------------------------------------
+ Seq Scan on tenk1 a
+   Filter: (NOT (hashed SubPlan 1))
+   SubPlan 1
+     ->  Index Only Scan using tenk1_unique2 on tenk1 b
+(4 rows)
+
+explain (costs off)
+select a.* from tenk1 a
+where exists (select 1 from tenk1 b where a.unique1 = b.unique2);
+                         QUERY PLAN                         
+------------------------------------------------------------
+ Hash Semi Join
+   Hash Cond: (a.unique1 = b.unique2)
+   ->  Seq Scan on tenk1 a
+   ->  Hash
+         ->  Index Only Scan using tenk1_unique2 on tenk1 b
+(5 rows)
+
+explain (costs off)
+select a.* from tenk1 a
+where not exists (select 1 from tenk1 b where a.unique1 = b.unique2);
+                         QUERY PLAN                         
+------------------------------------------------------------
+ Hash Anti Join
+   Hash Cond: (a.unique1 = b.unique2)
+   ->  Seq Scan on tenk1 a
+   ->  Hash
+         ->  Index Only Scan using tenk1_unique2 on tenk1 b
+(5 rows)
+
+explain (costs off)
+select a.* from tenk1 a left join tenk1 b on a.unique1 = b.unique2
+where b.unique2 is null;
+                         QUERY PLAN                         
+------------------------------------------------------------
+ Hash Anti Join
+   Hash Cond: (a.unique1 = b.unique2)
+   ->  Seq Scan on tenk1 a
+   ->  Hash
+         ->  Index Only Scan using tenk1_unique2 on tenk1 b
+(5 rows)
+
 --
 -- regression test for proper handling of outer joins within antijoins
 --
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index 27e7e741a1..ccbbe5454c 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -624,6 +624,31 @@ LEFT JOIN (
 ) AS d ON (a.f1 = d.f1)
 WHERE d.f1 IS NULL;
 
+--
+-- basic semijoin and antijoin recognition tests
+--
+
+explain (costs off)
+select a.* from tenk1 a
+where unique1 in (select unique2 from tenk1 b);
+
+-- sadly, this is not an antijoin
+explain (costs off)
+select a.* from tenk1 a
+where unique1 not in (select unique2 from tenk1 b);
+
+explain (costs off)
+select a.* from tenk1 a
+where exists (select 1 from tenk1 b where a.unique1 = b.unique2);
+
+explain (costs off)
+select a.* from tenk1 a
+where not exists (select 1 from tenk1 b where a.unique1 = b.unique2);
+
+explain (costs off)
+select a.* from tenk1 a left join tenk1 b on a.unique1 = b.unique2
+where b.unique2 is null;
+
 --
 -- regression test for proper handling of outer joins within antijoins
 --