Select privileges on SYS schema views and objects

Here, I explain about 'select_catalog_role' and 'select any dictionary' privileges and the difference between them.

SQL> show user;
User is "scott"

SQL> select * from dba_objects where rownum<=1;
select * from dba_objects where rownum<=1
ORA-00942: table or view does not exist

SQL> select * from v$session where rownum<=1;
select * from v$session where rownum<=1
ORA-00942: table or view does not exist
Above, SCOTT was not able to access sys schema views (v$session, dba_objects)

SQL> conn system/YYYY@orcl
Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.1.0
Connected as system

SQL> show user
User is "system"

SQL> grant select_catalog_role to scott;
Grant succeeded

[from scott schema]
SQL> select count(*) from v$session;
COUNT(*)
----------
44

SQL> select count(*) from dba_objects;

COUNT(*)
----------
72517

Now, scott is able to access sys schema views.

So, select_catalog_role grants user to select sys schema views (only views, no other objects like table)

[from scott schema]
SQL> select count(*) from sys.OBJ$;
select count(*) from OBJ$
ORA-00942: table or view does not exist

scott is not able to access sys schema objects

[from system schema]
SQL> revoke select_catalog_role from scott;
Revoke succeeded

SQL> grant select any dictionary to scott;
Grant succeeded

[from scott schema]
SQL> select count(*) from v$session;
COUNT(*)
----------
45

SQL> select count(*) from sys.obj$;

COUNT(*)
----------
73425

So, SCOTT is able to select rows from sys schema views and tables

So, the conclusion is,

'select_catalog_role' provides access to all SYS schema views only
'select any dictinaly' provides access to all SYS schema objects (views and tables etc..)