How exactly foundationdb beats CAP theorem?

Question

Are foundationdb claims on consistency valid?

FoundationDB provides the strongest possible consistency model, sequential consistency (closely related to serializability from the database literature), providing the greatest possible ease of development.

If yes, How does it exactly circumvent CAP theorem and provide strong [sequential] consistency given that it is a distributed NOSQL database?

Answer 1

FoundationDB doesn't claim to circumvent CAP theorem. It can be classified as a CP system. During normal operation, any system can support all the three properties. But during a network partition, as per CAP theorem, a system has to make a choice between availability (returning data that might be stale) vs consistency (returning errors). FoundationDB claims to choose consistency in those cases.