database implementation for apps like instagram

Question

I'm wondering how do apps like snapchat and instagram store pictures and user records in database.

Say I have a user table, how would they maintain list of followers for each user? Would they store the list of followers for each entry in user table or make a separate table for follow event and make an entry every time someone follows someone.

Also, for storing pictures, I'm guessing they would dump the pictures in a mass storage server space and store the URL in tables. Is there a better way of implementing this? If not, what kind of mass storage server would they go for? Dedicated or shared servers?

Thanks.

Answer 1

You should read Instagram Engineering post at tumblr. This will let you know there technology stack.

And this will also help overall.