pg_shadow overusage

I'd like to keep a complete history of everything that users of the
system does from the database level (as there are a number of
applications, and backend workers).  I've done this through various
rules, triggers.

The next step is to try to tie a name to it.  getpgusername() supplies
that perfectly.  The real question is, how many users can be in
pg_shadow without the system thrashing.

We're looking to start with approx. 20 000, and will likely grow that
number to 100k users in a years time (I understand a goal for 7.2 is
to get rid of the OID limit :).

Will pg_shadow and the database in general barf with that number of
users in the database?  A limit of 40 simultaneous connections should
suffice for our needs as user sessions will be quite short.

I also want to FOREIGN KEY the usename column in pg_shadow, I'll
assume that adding a unique index won't hurt anything (as I've not
noticed any problems on the test system thus far).

Thanks for any input.

--
Rod Taylor

There are always four sides to every story: your side, their side, the
truth, and what really happened.