RocksDB
maang.io System Design Series
RocksDB is an embeddable, high-performance LSM-tree key-value store (a LevelDB fork) that shows up as the storage engine inside other systems — Kafka Streams, Flink state, MyRocks, CockroachDB. Master its write path (memtable → WAL → SSTables), leveled compaction, and the write/read/space-amplification trade-offs, and you understand the engine under half the modern data infrastructure.
This deep dive comes in three parts:
- Foundations & Core Concepts — the LSM model, column families, and where RocksDB is embedded.
- Internals — compaction strategies, bloom filters, block cache, and amplification tuning, with worked numbers.
- Interview — Staff/Principal Q&A: LSM vs B-tree and tuning for a workload.