Mariel Cherkassky <mariel.cherkassky@xxxxxxxxx> 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