Bin Wang is a database engineer and educator publishing deep technical material on the internals of MySQL and PostgreSQL — the two most-used open-source relational databases in the modern web stack. His material is unusually rigorous for the YouTube tutorial market, going into the actual implementation, on-disk format, and trace-level performance analysis of these systems.
His CourseFlix listing carries two Bin Wang courses: Explore MySQL — A Beginner's Journey into Database Internals and PostgreSQL Uncovered — Internals, Trace Analysis, and Performance. Material is paid and aimed at engineers ready to treat the database as a first-class object of study.