Beyond "Pick Two": Real-World Trade Offs

This is Part 4 of a 4-part series on the CAP Theorem and distributed systems trade-offs. Read Part 1, Part 2, or Part 3 if you haven’t already. We’ve dedicated three posts to treating CP and AP as binary choices. etcd is CP. DynamoDB is AP. Pick a side. But that’s not how real systems work. MongoDB can be CP or AP depending on your configuration. Cassandra lets you choose per query. Even PostgreSQL, which we covered as a CP system in Part 2, flips to AP behavior with async replication. The line