Interesting that he advocates MySQL. PostgreSQL can index and interact with the JSON stored in it's columns, which make it a better choice as a NoSQL replacement.
http://www.postgresql.org/docs/9.4/static/datatype-json.html
http://www.postgresql.org/docs/9.4/static/datatype-json.html
So you can extract part of a Json document and index it. The optimizer can also match Json expressions to indexes