Multi-leader replication allows writes to multiple nodes:
Use cases:
- Multi-datacenter deployments (leader per DC)
- Offline-capable applications
- Collaborative editing
Challenge: Write conflicts when same data modified on different leaders.
Conflict resolution strategies:
- Last-write-wins (LWW): Timestamp decides. Simple but loses data.
- Merge: Combine changes automatically.
- Custom logic: Application-specific resolution.
- Conflict-free data types (CRDTs): Data structures that merge deterministically.
Avoid multi-leader unless you specifically need it. The complexity is significant.