Build Your Own Database

Learn how to build a key-value database from scratch by starting with a simple file-based approach and progressively solving real-world problems. The guide walks through implementing append-only logs, file segmentation and compaction, hash table indices for fast lookups, and sorted string tables with sparse indices. It culminates in building an LSM (Log-Structured Merge) tree—the same data structure powering production databases like LevelDB and DynamoDB—by combining an in-memory sorted list with on-disk storage for persistence and performance.