Can't grant privilege on column to user via role?

Question

Hi:
From what I read in the docs I should be able to create a role that has UPDATE privs on a column of a table, and then grant that role to a user, who should be able to update the column of the table. I get "insufficient privileges" when I try that, although it works as advertised if I grant directly to the user. Am I mis-reading the docs?
Session GAFF:
CREATE TABLE "GAFF"."FOO2"
   (    "F1" NUMBER,
    "F2" NUMBER,
    "F3" VARCHAR2(50),
    "F4" NUMBER,
     CONSTRAINT "FOO2_PK" PRIMARY KEY ("F1")
create role foo2_u_f2;
grant update (f2) on foo2 to foo2_u_f2 ;
grant select on gaff.foo2 to play ;
grant foo2_u_f2 to play ;session PLAY:
update gaff.foo2 set f2 = 1 where f1 = 1ORA-01031: insufficient privileges

Answer 1

Most likely role foo2_u_f2 is not a default role for user play. Initially, when user is created default role is set to ALL. Later it can be changed to NONE or a set of roles. Login as play and issue:
select * from session_roles
/I bet you will not see foo2_u_f2. Then issue:
select granted_role,default_role from user_role_privs
/That will give you a list of user play default roles. You can either issue:
set role foo2_u_f2
/This will enable foo2_u_f2 role in current session. Or you can login as privileged user and issue ALTER USER DEFUALT ROLE ...,foo2_u_f2.
SY.