Postgres 12 and a db course

Postgres 12 was recently released with some great features like concurrent reindex, jsonpath, and other stuff: https://www.postgresql.org/about/news/1976/  and https://www.postgresql.org/docs/12/release-12.html are good general info pages for the new stuff there.

Then, this is a great course about databases. It is about the internals of databases: https://www.youtube.com/watch?v=1D81vXw2T_w&list=PLSE8ODhjZXjbohkNBWQs_otTrBTrjyohi&index=1 . Really cool (at least the first 4 lectures).

Another sql thingie:
Julia Evans has this select order of execution that also is quite helpful if you're learning SQL https://news.ycombinator.com/item?id=21150606 .

EDIT: An advanced db course from Pavlo (great, more courses!): https://www.youtube.com/playlist?list=PLSE8ODhjZXja7K1hjZ01UTVDnGQdx5v5U