CockroachDB's Consistency Model

CockroachDB is an open-source, distributed SQL database that provides a sophisticated consistency model, which exceeds standard serializability but falls short of strict serializability, while ensuring no stale reads in transactions. The database employs multi-version concurrency control (MVCC) to manage transaction isolation and guarantees that once a write transaction is committed, all subsequent read transactions will see it, thereby preventing stale reads. CockroachDB's implementation involves a transaction layer that assigns timestamps to ensure correct transaction ordering, even across unsynchronized nodes. Although it allows a rare anomaly known as "causal reverse," where concurrent transactions might appear out of order, this is mitigated by ensuring overlapping read/write sets are properly synchronized. CockroachDB effectively balances high consistency with performance and resilience, making it a compelling choice for distributed systems despite not offering full strict serializability.