创建新账号，并赋予该账号基于schema只读权限

   create role  user_select LOGIN  NOSUPERUSER NOCREATEDB NOCREATEROLE  encrypted password '123456';
   grant connect on database report to user_select;
   \c report report
   grant usage on schema report to user_select;
   grant select on all tables in schema report to user_select;
   revoke select on all tables in schema report from  user_select;


赋予该账号只读及于表的只读权限
grant select on COMMENT to user_select;
grant select on RECOMMENT to user_select;