diff --git a/src/test/regress/expected/alter_table_set_access_method.out b/src/test/regress/expected/alter_table_set_access_method.out
index 8a6f335a7..938c6bc0d 100644
--- a/src/test/regress/expected/alter_table_set_access_method.out
+++ b/src/test/regress/expected/alter_table_set_access_method.out
@@ -1,5 +1,6 @@
--- test for Postgres version
--- should error before PG12
+--
+-- ALTER_TABLE_SET_ACCESS_METHOD
+--
 CREATE TABLE alter_am_pg_version_table (a INT);
 SELECT alter_table_set_access_method('alter_am_pg_version_table', 'columnar');
 NOTICE:  creating a new table for public.alter_am_pg_version_table
@@ -770,8 +771,15 @@ RESET client_min_messages;
 create table events (event_id bigserial, event_time timestamptz default now(), payload text);
 create index on events (event_id);
 insert into events (payload) select 'hello-'||s from generate_series(1,10) s;
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 16 AS server_version_ge_16
+\gset
 BEGIN;
+  \if :server_version_ge_16
+  SET LOCAL debug_parallel_query = regress;
+  \else
   SET LOCAL force_parallel_mode = regress;
+  \endif
   SET LOCAL min_parallel_table_scan_size = 1;
   SET LOCAL parallel_tuple_cost = 0;
   SET LOCAL max_parallel_workers = 4;
diff --git a/src/test/regress/expected/columnar_fallback_scan.out b/src/test/regress/expected/columnar_fallback_scan.out
index c31db0c43..b65e4118c 100644
--- a/src/test/regress/expected/columnar_fallback_scan.out
+++ b/src/test/regress/expected/columnar_fallback_scan.out
@@ -21,7 +21,14 @@ select count(*), min(i), max(i), avg(i) from fallback_scan;
 -- Negative test: try to force a parallel plan with at least two
 -- workers, but columnar should reject it and use a non-parallel scan.
 --
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 16 AS server_version_ge_16
+\gset
+\if :server_version_ge_16
+set debug_parallel_query = regress;
+\else
 set force_parallel_mode = regress;
+\endif
 set min_parallel_table_scan_size = 1;
 set parallel_tuple_cost = 0;
 set max_parallel_workers = 4;
@@ -39,7 +46,11 @@ select count(*), min(i), max(i), avg(i) from fallback_scan;
  150000 |   1 | 150000 | 75000.500000000000
 (1 row)
 
-set force_parallel_mode to default;
+\if :server_version_ge_16
+set debug_parallel_query = default;
+\else
+set force_parallel_mode = default;
+\endif
 set min_parallel_table_scan_size to default;
 set parallel_tuple_cost to default;
 set max_parallel_workers to default;
diff --git a/src/test/regress/expected/columnar_indexes.out b/src/test/regress/expected/columnar_indexes.out
index 2a7c09634..cd05108b2 100644
--- a/src/test/regress/expected/columnar_indexes.out
+++ b/src/test/regress/expected/columnar_indexes.out
@@ -1,4 +1,6 @@
 --
+-- COLUMNAR_INDEXES
+--
 -- Testing indexes on on columnar tables.
 --
 CREATE SCHEMA columnar_indexes;
@@ -598,6 +600,9 @@ create table events (event_id bigserial, event_time timestamptz default now(), p
 BEGIN;
   -- this wouldn't flush any data
   insert into events (payload) select 'hello-'||s from generate_series(1, 10) s;
+  SHOW server_version \gset
+  SELECT substring(:'server_version', '\d+')::int >= 16 AS server_version_ge_16
+  \gset
   -- Since table is large enough, normally postgres would prefer using
   -- parallel workers when building the index.
   --
@@ -609,7 +614,11 @@ BEGIN;
   -- by postgres and throws an error. For this reason, here we don't expect
   -- following commnad to fail since we prevent using parallel workers for
   -- columnar tables.
+  \if :server_version_ge_16
+  SET LOCAL debug_parallel_query = regress;
+  \else
   SET LOCAL force_parallel_mode = regress;
+  \endif
   SET LOCAL min_parallel_table_scan_size = 1;
   SET LOCAL parallel_tuple_cost = 0;
   SET LOCAL max_parallel_workers = 4;
diff --git a/src/test/regress/expected/columnar_partitioning.out b/src/test/regress/expected/columnar_partitioning.out
index e84953a0b..cd530b3f9 100644
--- a/src/test/regress/expected/columnar_partitioning.out
+++ b/src/test/regress/expected/columnar_partitioning.out
@@ -1,3 +1,6 @@
+--
+-- COLUMNAR_PARTITIONING
+--
 CREATE TABLE parent(ts timestamptz, i int, n numeric, s text)
   PARTITION BY RANGE (ts);
 -- row partitions
@@ -17,8 +20,15 @@ INSERT INTO parent SELECT '2020-03-15', 30, 300, 'three thousand'
   FROM generate_series(1,100000);
 INSERT INTO parent SELECT '2020-04-15', 30, 300, 'three thousand'
   FROM generate_series(1,100000);
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 16 AS server_version_ge_16
+\gset
 -- run parallel plans
+\if :server_version_ge_16
+SET debug_parallel_query = regress;
+\else
 SET force_parallel_mode = regress;
+\endif
 SET min_parallel_table_scan_size = 1;
 SET parallel_tuple_cost = 0;
 SET max_parallel_workers = 4;
@@ -121,7 +131,11 @@ SELECT count(*), sum(i), min(i), max(i) FROM parent;
 (1 row)
 
 SET columnar.enable_custom_scan TO DEFAULT;
+\if :server_version_ge_16
+SET debug_parallel_query TO DEFAULT;
+\else
 SET force_parallel_mode TO DEFAULT;
+\endif
 SET min_parallel_table_scan_size TO DEFAULT;
 SET parallel_tuple_cost TO DEFAULT;
 SET max_parallel_workers TO DEFAULT;
diff --git a/src/test/regress/sql/alter_table_set_access_method.sql b/src/test/regress/sql/alter_table_set_access_method.sql
index d7720cfda..24dc89fe4 100644
--- a/src/test/regress/sql/alter_table_set_access_method.sql
+++ b/src/test/regress/sql/alter_table_set_access_method.sql
@@ -1,5 +1,7 @@
--- test for Postgres version
--- should error before PG12
+--
+-- ALTER_TABLE_SET_ACCESS_METHOD
+--
+
 CREATE TABLE alter_am_pg_version_table (a INT);
 SELECT alter_table_set_access_method('alter_am_pg_version_table', 'columnar');
 DROP TABLE alter_am_pg_version_table;
@@ -258,8 +260,16 @@ create table events (event_id bigserial, event_time timestamptz default now(), p
 create index on events (event_id);
 insert into events (payload) select 'hello-'||s from generate_series(1,10) s;
 
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 16 AS server_version_ge_16
+\gset
+
 BEGIN;
+  \if :server_version_ge_16
+  SET LOCAL debug_parallel_query = regress;
+  \else
   SET LOCAL force_parallel_mode = regress;
+  \endif
   SET LOCAL min_parallel_table_scan_size = 1;
   SET LOCAL parallel_tuple_cost = 0;
   SET LOCAL max_parallel_workers = 4;
diff --git a/src/test/regress/sql/columnar_fallback_scan.sql b/src/test/regress/sql/columnar_fallback_scan.sql
index 28e521eaf..93a701062 100644
--- a/src/test/regress/sql/columnar_fallback_scan.sql
+++ b/src/test/regress/sql/columnar_fallback_scan.sql
@@ -20,7 +20,16 @@ select count(*), min(i), max(i), avg(i) from fallback_scan;
 -- Negative test: try to force a parallel plan with at least two
 -- workers, but columnar should reject it and use a non-parallel scan.
 --
+
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 16 AS server_version_ge_16
+\gset
+
+\if :server_version_ge_16
+set debug_parallel_query = regress;
+\else
 set force_parallel_mode = regress;
+\endif
 set min_parallel_table_scan_size = 1;
 set parallel_tuple_cost = 0;
 set max_parallel_workers = 4;
@@ -28,7 +37,11 @@ set max_parallel_workers_per_gather = 4;
 explain (costs off) select count(*), min(i), max(i), avg(i) from fallback_scan;
 select count(*), min(i), max(i), avg(i) from fallback_scan;
 
-set force_parallel_mode to default;
+\if :server_version_ge_16
+set debug_parallel_query = default;
+\else
+set force_parallel_mode = default;
+\endif
 set min_parallel_table_scan_size to default;
 set parallel_tuple_cost to default;
 set max_parallel_workers to default;
diff --git a/src/test/regress/sql/columnar_indexes.sql b/src/test/regress/sql/columnar_indexes.sql
index 34895f503..28716c970 100644
--- a/src/test/regress/sql/columnar_indexes.sql
+++ b/src/test/regress/sql/columnar_indexes.sql
@@ -1,4 +1,6 @@
 --
+-- COLUMNAR_INDEXES
+--
 -- Testing indexes on on columnar tables.
 --
 
@@ -448,6 +450,10 @@ BEGIN;
   -- this wouldn't flush any data
   insert into events (payload) select 'hello-'||s from generate_series(1, 10) s;
 
+  SHOW server_version \gset
+  SELECT substring(:'server_version', '\d+')::int >= 16 AS server_version_ge_16
+  \gset
+
   -- Since table is large enough, normally postgres would prefer using
   -- parallel workers when building the index.
   --
@@ -459,7 +465,12 @@ BEGIN;
   -- by postgres and throws an error. For this reason, here we don't expect
   -- following commnad to fail since we prevent using parallel workers for
   -- columnar tables.
+
+  \if :server_version_ge_16
+  SET LOCAL debug_parallel_query = regress;
+  \else
   SET LOCAL force_parallel_mode = regress;
+  \endif
   SET LOCAL min_parallel_table_scan_size = 1;
   SET LOCAL parallel_tuple_cost = 0;
   SET LOCAL max_parallel_workers = 4;
diff --git a/src/test/regress/sql/columnar_partitioning.sql b/src/test/regress/sql/columnar_partitioning.sql
index 8ae26ee3e..01a9e892e 100644
--- a/src/test/regress/sql/columnar_partitioning.sql
+++ b/src/test/regress/sql/columnar_partitioning.sql
@@ -1,3 +1,6 @@
+--
+-- COLUMNAR_PARTITIONING
+--
 
 CREATE TABLE parent(ts timestamptz, i int, n numeric, s text)
   PARTITION BY RANGE (ts);
@@ -21,8 +24,16 @@ INSERT INTO parent SELECT '2020-03-15', 30, 300, 'three thousand'
 INSERT INTO parent SELECT '2020-04-15', 30, 300, 'three thousand'
   FROM generate_series(1,100000);
 
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 16 AS server_version_ge_16
+\gset
+
 -- run parallel plans
+\if :server_version_ge_16
+SET debug_parallel_query = regress;
+\else
 SET force_parallel_mode = regress;
+\endif
 SET min_parallel_table_scan_size = 1;
 SET parallel_tuple_cost = 0;
 SET max_parallel_workers = 4;
@@ -46,7 +57,11 @@ EXPLAIN (costs off) SELECT count(*), sum(i), min(i), max(i) FROM parent;
 SELECT count(*), sum(i), min(i), max(i) FROM parent;
 SET columnar.enable_custom_scan TO DEFAULT;
 
+\if :server_version_ge_16
+SET debug_parallel_query TO DEFAULT;
+\else
 SET force_parallel_mode TO DEFAULT;
+\endif
 SET min_parallel_table_scan_size TO DEFAULT;
 SET parallel_tuple_cost TO DEFAULT;
 SET max_parallel_workers TO DEFAULT;