There have been a ton of discussions around this area over the years. The short answer is that if you think you need to prevent people from seeing the contents of the system catalogs, Postgres is not the database for you. I don't really foresee that changing, because it would break at least as many use-cases as it would enable. The thread David referenced only talks about side-effects on pg_dump, but there are many other applications that would be just as broken if we restricted this.
Thank you for information. I understood community's concern and policy. Regards, Shigeo Hirose
