PostgreSQL implements transactions and MVCC using tuple versioning and a background vacuum process. This design offers simplicity of concurrency control but has trade-offs, like table and index bloat and increased maintenance complexity of the vacuum process. OrioleDB is an alternative storage engine for PostgreSQL which introduces undo logs to implement transactions and MVCC. Undo logs offer immediate cleanup of tuples without additional vacuum process. This talk will examine the trade-offs of PostgreSQL’s current MVCC design. Then it will introduce the concept of undo logging, explain how OrioleDB implements it. The talk will provide a technical overview of how undo logs work in OrioleDB.