diff --git a/src/test/regress/input/parallel_indexonly_scan.source b/src/test/regress/input/parallel_indexonly_scan.source
new file mode 100644
index 0000000000000000000000000000000000000000..af6007612ad4ed50bf526fa0635b556c5f4554ad
--- /dev/null
+++ b/src/test/regress/input/parallel_indexonly_scan.source
@@ -0,0 +1,31 @@
+drop schema if exists test_parallel_indexonly_scan cascade;
+create schema test_parallel_indexonly_scan;
+set current_schema='test_parallel_indexonly_scan';
+-- create test table and indexonly
+DROP TABLE IF EXISTS parallel_indexonly_01;
+CREATE TABLE parallel_indexonly_01(a int);
+INSERT INTO parallel_indexonly_01 VALUES (generate_series(1, 1000000));
+CREATE INDEX index_parallel_indexonly_01 ON parallel_indexonly_01(a);
+SET enable_seqscan = OFF;
+SET enable_bitmapscan = OFF;
+SET enable_indexscan = OFF;
+SET query_dop = 2;
+-- encourage optimizer to choose parallel path
+SET smp_thread_cost = 0;
+
+-- parallel indexonly scan in equality case
+SELECT * FROM parallel_indexonly_01 WHERE a=100;
+SELECT * FROM parallel_indexonly_01 WHERE a=100 AND a=10000;
+
+-- parallel indexonly scan in scope case
+EXPLAIN (COSTS OFF) SELECT * FROM parallel_indexonly_01 WHERE a>10000 AND a<20000;
+SELECT COUNT(a) FROM parallel_indexonly_01 WHERE a>10000 AND a<20000;
+EXPLAIN (COSTS OFF) SELECT * FROM parallel_indexonly_01 WHERE a in (1000,10000,100000) ORDER BY a;
+SELECT * FROM parallel_indexonly_01 WHERE a in (1000,10000,100000) ORDER BY a;
+
+--cleanup env
+reset enable_seqscan;
+reset enable_bitmapscan;
+reset enable_indexscan;
+reset query_dop;
+reset smp_thread_cost;
diff --git a/src/test/regress/output/parallel_indexonly_scan.source b/src/test/regress/output/parallel_indexonly_scan.source
new file mode 100644
index 0000000000000000000000000000000000000000..56b0bf9ce103ed3c6a6fd693854c7c78dd0c00db
--- /dev/null
+++ b/src/test/regress/output/parallel_indexonly_scan.source
@@ -0,0 +1,67 @@
+drop schema if exists test_parallel_indexonly_scan cascade;
+NOTICE:  schema "test_parallel_indexonly_scan" does not exist, skipping
+create schema test_parallel_indexonly_scan;
+set current_schema='test_parallel_indexonly_scan';
+-- create test table and indexonly
+DROP TABLE IF EXISTS parallel_indexonly_01;
+NOTICE:  table "parallel_indexonly_01" does not exist, skipping
+CREATE TABLE parallel_indexonly_01(a int);
+INSERT INTO parallel_indexonly_01 VALUES (generate_series(1, 1000000));
+CREATE INDEX index_parallel_indexonly_01 ON parallel_indexonly_01(a);
+SET enable_seqscan = OFF;
+SET enable_bitmapscan = OFF;
+SET enable_indexscan = OFF;
+SET query_dop = 2;
+-- encourage optimizer to choose parallel path
+SET smp_thread_cost = 0;
+-- parallel indexonly scan in equality case
+SELECT * FROM parallel_indexonly_01 WHERE a=100;
+  a  
+-----
+ 100
+(1 row)
+
+SELECT * FROM parallel_indexonly_01 WHERE a=100 AND a=10000;
+ a 
+---
+(0 rows)
+
+-- parallel indexonly scan in scope case
+EXPLAIN (COSTS OFF) SELECT * FROM parallel_indexonly_01 WHERE a>10000 AND a<20000;
+                                    QUERY PLAN                                    
+----------------------------------------------------------------------------------
+ Streaming(type: LOCAL GATHER dop: 1/2)
+   ->  Index Only Scan using index_parallel_indexonly_01 on parallel_indexonly_01
+         Index Cond: ((a > 10000) AND (a < 20000))
+(3 rows)
+
+SELECT COUNT(a) FROM parallel_indexonly_01 WHERE a>10000 AND a<20000;
+ count 
+-------
+  9999
+(1 row)
+
+EXPLAIN (COSTS OFF) SELECT * FROM parallel_indexonly_01 WHERE a in (1000,10000,100000) ORDER BY a;
+                                       QUERY PLAN                                       
+----------------------------------------------------------------------------------------
+ Sort
+   Sort Key: a
+   ->  Streaming(type: LOCAL GATHER dop: 1/2)
+         ->  Index Only Scan using index_parallel_indexonly_01 on parallel_indexonly_01
+               Index Cond: (a = ANY ('{1000,10000,100000}'::integer[]))
+(5 rows)
+
+SELECT * FROM parallel_indexonly_01 WHERE a in (1000,10000,100000) ORDER BY a;
+   a    
+--------
+   1000
+  10000
+ 100000
+(3 rows)
+
+--cleanup env
+reset enable_seqscan;
+reset enable_bitmapscan;
+reset enable_indexscan;
+reset query_dop;
+reset smp_thread_cost;