The OP is an engineer at Twitter...doesn't Twitter use NoSQL to store tweets? I know your critique of NoSQL is that it is an overreaction to the pain of schemas, so I'd like to see some discussion on how to implement lambda with data architecture that, at some point, uses document databases.

Thanks for the post...slideshare is annoying to read (on an iPad) but the content was digestible. Mostly, it helped remind me to download the update of the OP's book