Understanding MVCC and VACUUM

Welcome to understanding PostgreSQL's core! Today, we dive into Multi-Version Concurrency Control (MVCC). It's a fancy term for a simple, powerful idea.

MVCC is how PostgreSQL allows many users or applications to access and modify data at the same time without interfering with each other. Think of it as a traffic controller for your database.

Imagine a database without MVCC. If one user is reading a row, another user trying to update that same row would have to wait. This is called locking, and too much of it can make your database painfully slow.

MVCC solves this by ensuring that readers don't block writers, and writers don't block readers. Everyone gets their own consistent view of the data.