text: \echo --start_ignore
  set gp_enable_column_oriented_table=on;
  \echo --end_ignore
  DROP TABLE IF EXISTS m; 
  CREATE TABLE m ();
  set allow_system_table_mods='DML';
  delete from gp_distribution_policy where localoid='m'::regclass;
  reset allow_system_table_mods;
  ALTER TABLE m ADD column a integer default null;
  ALTER TABLE m ADD column b integer default null;
  ALTER TABLE m ADD column c integer default null;
  