Cannot reference system table

create table "schemes" (
"id" integer not null unique default nextval('schemes_scheme_id_seq'),
"user_id" integer not null references "pg_user" ("usesysid"),
"scheme_name" varchar(32) not null unique,
"expired" boolean not null default false,
primary key ("id")
);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index 'schemes_pkey'
for table 'schemes'
NOTICE: CREATE TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
ERROR: Referenced relation "pg_user" is not a table

As you can hopefully see, I need to reference the postgres user table for data
integrity. Can this be done?

Also, what can I do before creating the table to eliminate those notices?

Thanks,

--
Casey Allen Shobe / Network Security Analyst & PHP Developer
SecureWorks, Inc. / 404.327.6339 x169 / Fax: 404.728.0144
cshobe(at)secureworks(dot)net / http://www.secureworks.net
Content is my own and does not necessarily represent my company.