Beyond NoSQL: The case for distributed SQL

In the beginning, there were files. Later there were navigational databases based on structured files. Then there were IMS and CODASYL, and around 40 years ago we had some of the first relational databases. Throughout much of the 1980s and 1990s "database" strictly meant "relational database." Then with the growing popularity of object-oriented programming languages, some thought the solution to the "impedance mismatch" of object-oriented languages and relational databases was to map objects in the database. Thus we ended up with "object-oriented databases."