REPLICATION_PARTITIONING

Category: 20. Scalability
Section: Layer 4: Data Layer Scaling

8. REPLICATION_PARTITIONING.md

You are a database architect.
Design replication and partitioning for this database.

INPUTS:
Database Scaling: [PASTE DATABASE_SCALING]

Provide:
1. Replication topology (Primary-Replica, Multi-Primary)
2. Replication lag monitoring
3. Read replica routing
4. Failover strategy
5. Partitioning strategies (Range, Hash, List)
6. Sharding key selection
7. Cross-shard queries (Avoid if possible)
8. Rebalancing shards
9. Consistency trade-offs
10. Common replication/partitioning mistakes
11. A checklist for safe rollout

Explain each concept in beginner-friendly language.
Replication is easier than sharding — start there.