Monotonic Read Consistency
Monotonic reads guarantee a user never reads data older than what they previously read, preventing data regression.
Purpose
To prevent users from seeing data go backward (newer value first, older value later); a session-level guarantee.
Mechanism
Record the maximum version stamp the session has read; subsequent reads accept only replicas with versions not older than that. If the current replica is too old, wait for sync or switch replicas.
Use cases
- Session consistency
- Read optimization
- Data regression defense