Wide-Column Stores (Cassandra)
Difficulty: Medium | Topic #20
What to Learn
Partition key selection for even distribution, clustering keys for ordering, tunable consistency (ONE, QUORUM, ALL), compaction strategies, modeling around access patterns (no joins).
Resources
- Hello Interview: Cassandra Deep Dive ↗
- ByteByteGo: Wide Column NoSQL Database Deep Dive ↗
- Gaurav Sen: What is Cassandra? ↗
Covered by Problems
| Problem | Difficulty | Link |
|---|---|---|
| Messaging App (WhatsApp) | Medium | → |
| Activity Tracker (Strava) | Medium | → |
| Live Comments (FB Live) | Medium | → |
Key Concepts to Master
- Partition key drives data distribution — bad choices cause hot nodes
- Clustering key sorts rows within a partition for range scans
- QUORUM consistency for read-your-writes guarantee across replicas
- Compaction strategies (SizeTiered for writes, Leveled for reads)
- Data modeling around query patterns — no secondary indexes by default