SELECT 'K' AS key_flag, t.table_name AS k_tablename, l.column_name AS k_column_name, k.table_name AS f_table_name, k.column_name AS f_coumn_name, t.constraint_name
           FROM information_schema.constraint_table_usage t
      JOIN information_schema.constraint_column_usage l ON t.constraint_name::text = l.constraint_name::text
   JOIN information_schema.key_column_usage k ON t.constraint_name::text = k.constraint_name::text
   JOIN information_schema.table_constraints c ON t.constraint_name::text = c.constraint_name::text
  WHERE c.constraint_type::text = 'FOREIGN KEY'::text
UNION ALL 
         SELECT 'F' AS key_flag, k.table_name AS k_tablename, k.column_name AS k_column_name, t.table_name AS f_table_name, l.column_name AS f_coumn_name, t.constraint_name
           FROM information_schema.key_column_usage k
      JOIN information_schema.table_constraints c ON k.constraint_name::text = c.constraint_name::text
   JOIN information_schema.constraint_table_usage t ON k.constraint_name::text = t.constraint_name::text
   JOIN information_schema.constraint_column_usage l ON t.constraint_name::text = l.constraint_name::text
  WHERE c.constraint_type::text = 'FOREIGN KEY'::text
  ORDER BY 2, 1 DESC;