Calvin: Fast Distributed Transactions for Partitioned Database Systems

Why this one

Read this after Spanner and The Google File System if you want the other fork in the road for distributed databases. Spanner spends machinery on making time trustworthy enough to serialize transactions across replicas. Calvin instead says: stop discovering the order while locks are held. Put every transaction into a global log first, then make execution a deterministic consequence of that log. The trick is easy to say and hard to internalize because it moves the hard part out of the storage engine and into sequencing, batching, and knowing read and write sets early. People often remember Calvin as just 2PC avoidance, but the deeper lesson is architectural: if all replicas already agree on the input order, concurrency control becomes replay, not negotiation. Worth your evening because it gives you a clean mental model for when coordination is paid upfront and when it is paid in the hot path.