Use execSQL for replication slot creation

Author: aviralgarg05

gpMgmt/bin/gppylib/commands/pg.py

@@ -36,10 +36,9 @@ def ensure_replication_slot_exists(source_host, source_port,
         if slot_exists > 0:
             return False
 
-        dbconn.querySingleton(
+        dbconn.execSQL(
             conn,
-            "SELECT slot_name "
-            "FROM pg_catalog.pg_create_physical_replication_slot('{}')"
+            "SELECT pg_catalog.pg_create_physical_replication_slot('{}')"
             .format(escaped_slot_name))
 
     return True

gpMgmt/bin/gppylib/commands/test/unit/test_unit_pg_base_backup.py

@@ -63,12 +63,14 @@ def test_ensure_replication_slot_exists_returns_false_when_slot_exists(self, moc
         self.assertIn("FROM pg_catalog.pg_replication_slots", mock_query_singleton.call_args[0][1])
         mock_conn.close.assert_called_once_with()
 
-    @patch('gppylib.commands.pg.dbconn.querySingleton', side_effect=[0, 'slot_name'])
+    @patch('gppylib.commands.pg.dbconn.execSQL')
+    @patch('gppylib.commands.pg.dbconn.querySingleton', return_value=0)
     @patch('gppylib.commands.pg.dbconn.connect')
     @patch('gppylib.commands.pg.dbconn.DbURL')
     def test_ensure_replication_slot_exists_creates_missing_slot(self, mock_dburl,
                                                                  mock_connect,
-                                                                 mock_query_singleton):
+                                                                 mock_query_singleton,
+                                                                 mock_exec_sql):
         mock_conn = Mock()
         mock_connect.return_value = mock_conn
 
@@ -77,10 +79,11 @@ def test_ensure_replication_slot_exists_creates_missing_slot(self, mock_dburl,
         self.assertTrue(created)
         mock_dburl.assert_called_once_with(hostname='source-host', port=5432, dbname='template1')
         mock_connect.assert_called_once_with(mock_dburl.return_value, utility=True)
-        self.assertEqual(2, mock_query_singleton.call_count)
-        self.assertIn("FROM pg_catalog.pg_replication_slots", mock_query_singleton.call_args_list[0][0][1])
+        self.assertEqual(1, mock_query_singleton.call_count)
+        self.assertIn("FROM pg_catalog.pg_replication_slots", mock_query_singleton.call_args[0][1])
+        mock_exec_sql.assert_called_once()
         self.assertIn("pg_create_physical_replication_slot('slot_name')",
-                      mock_query_singleton.call_args_list[1][0][1])
+                      mock_exec_sql.call_args[0][1])
         mock_conn.close.assert_called_once_with()
 
     @patch('gppylib.commands.pg.dbconn.querySingleton')