1.创建一个用户名为readonly密码为123456的用户

  CREATE USER readonly WITH ENCRYPTED PASSWORD '123456';

2.更新用户默认为只读事务

  alter user readonly set default_transaction_read_only=on;

3.把所有库的public的USAGE权限给到readonly

  GRANT USAGE ON SCHEMA public to readonly;      

4.授予select权限(要进入到具体数据库操作在哪个db环境下执行就授予那个db的权限)

   grant select on all tables in schema public to readonly;