Strong Consistency
Strong consistency guarantees reads always return the most recently written value; linearizability is its strongest form.
Purpose
To require reads to see all previously acknowledged writes, for strictly consistent scenarios like financial transactions.
Mechanism
Linearizability: once a write completes, all reads see the new value. Implemented via synchronous replication (Quorum W+R>N), consensus protocols (Paxos/Raft), or global locks. The cost is higher latency and lower availability.
Use cases
- Financial system design
- Linearizability implementation
- Synchronous replication