I'm working on a new chapter for my course Mastery with SQL (https://www.masterywithsql.com https://www.masterywithsql.com) covering query performance and index

I'm working on a new chapter for my course Mastery with SQL (https://www.masterywithsql.com https://www.masterywithsql.com) covering query performance and indexing with PostgreSQL. I want to really allow everyone to see first-hand the impact of re-writing queries to be more performant and adding the right indexes so I've been spending a lot of time to create great exercises where you get to optimise poorly performing queries over some very large and interesting data sets. I launched the course on HN a bit over a week ago and had a really great response (https://news.ycombinator.com/item?id=20260292 https://news.ycombinator.com/item?id=20260292) so has been great motivation to continue working hard! Really enjoying myself at the moment.