From bcb162976f7bad994130d8ae693c586b83399fe6 Mon Sep 17 00:00:00 2001
From: Hadi Moshayedi <hadi@moshayedi.net>
Date: Mon, 1 Feb 2021 16:20:53 -0800
Subject: [PATCH] Fix #4608

---
 src/backend/columnar/cstore_tableam.c         |  2 +-
 .../expected/columnar_citus_integration.out   | 26 +++++++++++++++++++
 .../sql/columnar_citus_integration.sql        | 10 +++++++
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/backend/columnar/cstore_tableam.c b/src/backend/columnar/cstore_tableam.c
index 4a5b3026f..7dd143277 100644
--- a/src/backend/columnar/cstore_tableam.c
+++ b/src/backend/columnar/cstore_tableam.c
@@ -164,7 +164,7 @@ columnar_beginscan(Relation relation, Snapshot snapshot,
 														 parallel_scan,
 														 flags, attr_needed, NULL);
 
-	pfree(attr_needed);
+	bms_free(attr_needed);
 
 	return scandesc;
 }
diff --git a/src/test/regress/expected/columnar_citus_integration.out b/src/test/regress/expected/columnar_citus_integration.out
index 4b912467e..f80448b83 100644
--- a/src/test/regress/expected/columnar_citus_integration.out
+++ b/src/test/regress/expected/columnar_citus_integration.out
@@ -1067,5 +1067,31 @@ SELECT 1 FROM master_remove_node('localhost', :master_port);
         1
 (1 row)
 
+-- verify reference table with no columns can be created
+-- https://github.com/citusdata/citus/issues/4608
+CREATE TABLE zero_col() USING columnar;
+SELECT create_reference_table('zero_col');
+ create_reference_table
+---------------------------------------------------------------------
+
+(1 row)
+
+select result from run_command_on_placements('zero_col', 'select count(*) from %s');
+ result
+---------------------------------------------------------------------
+ 0
+ 0
+(2 rows)
+
+-- add a column so we can ad some data
+ALTER TABLE zero_col ADD COLUMN a int;
+INSERT INTO zero_col SELECT i FROM generate_series(1, 10) i;
+select result from run_command_on_placements('zero_col', 'select count(*) from %s');
+ result
+---------------------------------------------------------------------
+ 10
+ 10
+(2 rows)
+
 SET client_min_messages TO WARNING;
 DROP SCHEMA columnar_citus_integration CASCADE;
diff --git a/src/test/regress/sql/columnar_citus_integration.sql b/src/test/regress/sql/columnar_citus_integration.sql
index 57a8ccd26..21e3c7f57 100644
--- a/src/test/regress/sql/columnar_citus_integration.sql
+++ b/src/test/regress/sql/columnar_citus_integration.sql
@@ -403,5 +403,15 @@ SELECT compression FROM columnar.options WHERE regclass = 'table_option_citus_lo
 DROP TABLE table_option_citus_local, table_option_citus_local_2;
 SELECT 1 FROM master_remove_node('localhost', :master_port);
 
+-- verify reference table with no columns can be created
+-- https://github.com/citusdata/citus/issues/4608
+CREATE TABLE zero_col() USING columnar;
+SELECT create_reference_table('zero_col');
+select result from run_command_on_placements('zero_col', 'select count(*) from %s');
+-- add a column so we can ad some data
+ALTER TABLE zero_col ADD COLUMN a int;
+INSERT INTO zero_col SELECT i FROM generate_series(1, 10) i;
+select result from run_command_on_placements('zero_col', 'select count(*) from %s');
+
 SET client_min_messages TO WARNING;
 DROP SCHEMA columnar_citus_integration CASCADE;