I want to know which database is used in Facebook?How the database is designed to make virtual friend list in the database of a user?
closed as not a real question by Jon Seigel, Derek Downey, JNK♦ Sep 6 '12 at 12:45
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I think its a simple tracking task of any particular user. At the time of creation of your personal ID on the facebook you provide few parameters like your school name and pass out of higher classes and Graduation batch and passout year. On the basis of these details they prepare a virtual friend list so as you send friend request to any one they catch this detail too and the chain now starts. Like Friend of Friend might be a friend.