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