Over the years I've found #BrentOzar's SQL Server #training to be massively useful. I'm hoping his #Postgres #PostgreSQL training will be equally useful.

His Fundamentals of Performance bundle (one-off purchase) is roughly half price until the end of this month. $200 off with the code GETINFORLIFE

https://smartpostgres.teachable.com/l/bundle/615876/fundamentals-of-performance