The CAP theorem is often used to describe the tradeoffs of available versus consistent systems. But the CAP theorem is often misunderstood and misrepresented. In this session we investigate the CAP properties of various MySQL replication setups, and show that it is impossible to claim a setup is AP or that it is CP. We will see how the properties can be non binary, and change across time, geography and workload. We will also observe where CAP's terms can be made irrelevant. This session takes the practical engineer's perspective and shows how we can gain the upper hand with reasonable tradeoffs.

February 05, 2019