SQL databases have ruled the way developers store data in applications for three decades. Databases are growing in a world where applications are standalone or connected to a highly reserved and controlled Local Area Network of many machines inside a single company. Since then, the relational model has become widely used and understood. The interaction with the database is done with the SQL language, which is a standard language. This degree of standardization was enough to keep things familiar so that people did not need to learn something new to persist data when the Internet and web applications were starting their lives.

SQL databases follow the Consistency-Availability-Partitioning (CAP) theorem for network distributed systems: only two of the three principles can be respected. In particular, SQL databases give up to partitioning (physically organizing data of the same database in different physical containers) to guarantee consistency and availability. Consistency...