text: --  @testpoint:opengauss关键字domain(非保留)，自定义数据类型名为domain
  --关键字domain作为数据类型不带引号，创建成功
  drop type if exists domain;
  CREATE TYPE domain AS (f1 int, f2 text);
  select typname from pg_type where typname ='domain';
  drop type domain;
  
  
  --关键字domain作为数据类型加双引号，创建成功
  drop type if exists "domain";
  CREATE TYPE "domain" AS (f1 int, f2 text);
  select typname from pg_type where typname ='domain';
  drop type "domain";
  
  --关键字domain作为数据类型加单引号，合理报错
  drop type if exists 'domain';
  CREATE TYPE 'domain' AS (f1 int, f2 text);
  select * from pg_type where typname ='domain';
  drop type 'domain';
  
  --关键字domain作为数据类型加反引号，合理报错
  drop type if exists `domain`;
  CREATE TYPE `domain` AS (f1 int, f2 text);
  select * from pg_type where typname =`domain`;
  drop type `domain`;