AdvancedSystem-Design
45 min
Design a Cross-Region Database Replication System
DatabasesReplicationConsistencyDisaster Recovery
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Interview Question
Design a database system that replicates across regions with low latency, conflict resolution, and disaster recovery.
Key Points to Cover
- Replication models: async, semi-sync, sync
- Conflict resolution: last-write-wins, CRDTs, app-level
- Disaster recovery: failover, RTO/RPO objectives
- Topology: active-active vs active-passive
- Monitoring and observability for replication lag
Evaluation Rubric
Clear replication models & trade-offs25% weight
Effective conflict resolution25% weight
Robust disaster recovery strategy25% weight
Operational observability & SLAs25% weight
Hints
- 💡Be explicit about RPO and RTO goals.
Common Pitfalls to Avoid
- ⚠️Underestimating the complexity of network latency across vast geographical distances.
- ⚠️Failing to adequately test conflict resolution strategies under realistic concurrent write scenarios.
- ⚠️Setting unrealistic RTO/RPO objectives that are not aligned with budget or technical feasibility.
- ⚠️Neglecting to implement comprehensive monitoring and alerting for replication lag and failover status.
- ⚠️Assuming that a 'one-size-fits-all' replication model or conflict resolution strategy will work for all data types and access patterns.
Potential Follow-up Questions
- ❓How do you handle schema migrations?
- ❓How do you test failover safely?
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