Eric Brewer posted the CAP theorem in early 2000.

In it he discusses three system attributes within the context of distributed databases as follows:

1. Consistency: The notion that all nodes see the same data at the same time.
2. Availability: A guarantee that every request to the system receives a response about whether it was successful or not.
3. Partition Tolerance: A quality STATING that the system CONTINUES to operate despite failure of part of the system.

The common understanding AROUND the CAP theorem is that a distributed database system may only provide at most 2 of the above 3 capabilities. As such, most NoSQL databases cite it as a basis for employing an eventual consistency model with respect to how database updates are handled.

Eric Brewer posted the CAP theorem in early 2000.

In it he discusses three system attributes within the context of distributed databases as follows:

The common understanding around the CAP theorem is that a distributed database system may only provide at most 2 of the above 3 capabilities. As such, most NoSQL databases cite it as a basis for employing an eventual consistency model with respect to how database updates are handled.