NRW Notation
Describes how Distributed Databases deal with consistency and reads and writes.
- R: Number of nodes that are read from
- W: Number of nodes that are written to
- N: Total number of nodes in the cluster
| NRW Configuration | Result |
|---|---|
| W=N R=1 | Read performance optimized, write costly (strong consistency) |
| W=1 R=N | Write performance optimized, read costly (strong consistency) |
| W+R ⇐ N | Eventual consistency |
| W+R > N | Quorum assembly, every read will see at least one copy of currently most recent update |
| N > W > 1 | Most common setting for NoSql Databases |