This presentation by Tim Moreton at NoSQL NOW! 2013 looks at the history of doing analytics in NoSQL databases. We look at the relative strengthes of normalized and denormalized approaches, and look at how Twitter and Facebook have built custom denormalized systems over NoSQL to support real-time analytics. We look at the lambda architecture, and show how Acunu Analytics provides OLAP cubes over NOSQL, combining denormalization with expressive SQL-like queries.
You can see the full talk here: