Not sure if this is what you are looking for but I found this paper useful on architecting databases. I read it as a complement to the CMU videos. https://dsf.berkeley.edu/papers/fntdb07-architecture.pdf
Otherwise there is surprisingly a lack of information about architecting databases online and you have to go to the source code of SQLite and PostgreSQL. I suspect this is because databases are some of the most complex systems in computer science and involve many trade secrets.