View Access Privileges

Question

Hi,
I learnt that if we want to create a view in a schema, the owner of the schema should have select,insert,update and delete privileges on all the tables on which the view should be based on.
But if we have got the above privilleges through a role rather than directly granted privileges, we cannot create a view.
Can some one please help me understand why it is so, and what difference does it make if a privilege is granted through role and granted directly
Thanks for your help
Your answers are very valuable to me . Thank you very much
Thanks
Ravi

Answer 1

The answer is
views (and procedures and functions and packages) are compiled and roles are volatile so potentially would have been changed after compilation of the view.
This is why roles are ignored during compilation.
You can compile procedure with definer rights (default) and invokers rights (adding 'authid current_user' before 'is')
Ideally you use the former, as you best create a procedure in the schema of the table.
Invokers rights do not apply to views.
All of this, as always, has already been asked 10000000000000000000000 times here, and the answers are in this forum, and in the documentation everyone here refuses to read.
Sybrand Bakker
Senior Oracle DBA