Document DB's aren't an invention of the past 10 years. SAS was invented in the 60's, Lotus Notes in the 80's. XML Databases were all the rage during the dotcom

Document DB's aren't an invention of the past 10 years. SAS was invented in the 60's, Lotus Notes in the 80's. XML Databases were all the rage during the dotcom bubble. The difference today is that open source projects have made document stores and 'nosql' technologies more accessible.