Hadoop in facebook
In 2011 , facebook released the paper "Apache hadoop goes realtime at facebook" . How the hadoop is participating in real time applications . 
For example , while updating status by any user on facebook . The notifications are send to every friend . Is this the application of mysql or cassandra or hadoop ? Which one of them is doing real time processing and how ? 
As far as i know , hadoop is mainly used for batch based analytics .
Hadoop in facebook
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In 2011 , facebook released the paper "Apache hadoop goes realtime at facebook" . How the hadoop is participating in real time applications . 
For example , while updating status by any user on facebook . The notifications are send to every friend . Is this the application of mysql or cassandra or hadoop ? Which one of them is doing real time processing and how ? 
As far as i know , hadoop is mainly used for batch based analytics .