The author is incorrect about JSON in mysql. You can in fact index individual columns in your JSON. They end up being generated columns that you then index. Not as slick or mature as postgres, but it does exist.
Edit: audited the rest of the post. Author is otherwise correct. Occasionally ignores some (admittedly ugly) workarounds for some issues. All in all, great post.
Edit: audited the rest of the post. Author is otherwise correct. Occasionally ignores some (admittedly ugly) workarounds for some issues. All in all, great post.