If you meant that you want to facebook.com/your_name. You have to login first, then open this URL below : www.facebook.com you'll get your easy URL and update your desirable name. It think it is allowing you to update once, can not be changed later.

Advantages: It supports very large size databases Security Consistency High level availability Lower downtime Good performance Oracle runs faster Disadvantages: Expensive Complex to maintain are few advantages and disadvantage of oracle.