I'll second that. I always like pouring over schemas that have been tested by heavy use - and wikimedia sure has.

The only thing that would make the png more valuable would be some accompanying discussion: I'd like to know

who was/were mostly responsible for the design. Seems like I had searched through WP itself one time but found surprisingly little.

what refactoring lessons they encountered during the history of the project.

Much good karma to someone who can get proper credit to the database team!