Postgres roles

In older versions of Postgres we had users and groups as two separate entities

Our IT department at work is called “sti”, that’s why:

-         I had a user “sti” (the username of our IT manager)

-         I had a group “sti” (the group containing all the users of our department: user1, user2…)

When we upgraded to PostgreSQL 8.2.4, came up the concept of roles; users and groups became one entity

So now I have in my database, only one role, called “sti”

My questions are:

1.      how do I identify the users assigned to this role :
(in the older version)
SELECT grolist from pg_group where groname = 'sti';

2.      how do I differ granting permissions on a table to the user sti from the whole members of the group sti
(in the older version)
GRANT SELECT ON table TO group sti;
GRANT SELECT,INSERT,UPDATE,DELETE ON table TO sti;

I’d appreciate any help regarding this issue

Pascal Tufenkji