Understanding InnoDB Tablespace Duplicate Check (MySQL Startup with Many Tables)

This post is a little long, please bear with me as after the intro, you can skip to the essential.In the last weeks / months, I have been working on understanding / improving MySQL startup with many tables. I already wrote three posts on the subject, they are listed below. In this post, I focus on describing the startup phase InnoDB Tablespace Duplicate Check (Duplicate Check for