Mariel Cherkassky <mariel.cherkassky@gmail.com> writes:
> I checked it also in version 9.6, and in this version I can edit the
> pg_authid table. I'm suppose to get an error that the table is a system
> catalog or am I wrong ?
No, the "system catalog modification" restriction only applies to DDL
on the system catalogs --- for instance, adding/removing a column, which
our C code couldn't cope with. You're free to change their contents by
hand if you're a superuser. (And if you break something that way, you
get to keep both pieces. But sometimes it's necessary.)
regards, tom lane