Wide-column stores organize data by column families:
Row Key: user_123
profile: {name: "John", email: "j@x.com"}
activity: {last_login: "2024-01", posts: 42}
Characteristics:
- Rows can have different columns
- Column families stored together on disk
- Excellent for sparse data
- Optimized for write-heavy workloads
Use cases:
- Time-series data
- Event logging
- IoT sensor data
Examples: Apache Cassandra, HBase, ScyllaDB
Think of it as a two-dimensional key-value store.