How does MVCC (Multi-Version Concurrency Control) work

Introduction In this article, I’m going to explain how the MVCC (Multi-Version Concurrency Control) mechanism works using PostgreSQL as a reference implementation. In Concurrency Control theory, there are two ways you can deal with conflicts: You can avoid them, by employing a pessimistic locking mechanism (e.g. Read/Write locks, Two-Phase Locking) You can allow conflicts to occur, but you need to detect them using an optimistic locking mechanism (e.g. logical clock, MVCC) Because MVCC (Multi-Version Concurrency Control) is such a prevalent Concurrency Control technique (not only in relational database systems, in this article, … Continue reading How does MVCC (Multi-Version Concurrency Control) work