The document discusses BoltDB, an embedded key-value database written in Go. It describes how Tokopedia used BoltDB to store image mappings more efficiently than MongoDB. BoltDB provided fast retrieval, scalability to thousands of queries per second, and persistence without recomputing on startup. While not a traditional database, BoltDB's ACID semantics and ease of use made it suitable for Tokopedia's read-heavy use case of serving images from cached storage.