Nice overview. I particularly like how they visualized BigTable and MapReduce. Will make it easier for some to understand. For those liking Spanner, Google has exceeded that with their awesome F1 RDBMS (built on Spanner/GFS) below:

https://static.googleusercontent.com/media/research.google.c...

Can't wait for someone to clone this. Come to think of it, has anyone cloned Spanner? I recall some calling GPS a hack but I thought it was engineering brilliance. Spanner was some good work, too.