[cmrdporcupine]

Not a book, but I recommend the database class lectures from @apavlo's group at CMU.

https://www.youtube.com/c/cmudatabasegroup

All the classes (intro and advanced) are online, as well as presentations and lectures about industry products.

They are very useful.

Also, from a more high level theoretical CS and less physical-implementation focused POV, the "Alice" book ("Foundations of Databases") is amazing (though very dense and mathematical). Focuses on the relational algebra and Datalog (and the translation of that into the Rel Algebra). Getting print copies is hard now (my used copy arrived with a broken spine and pages falling out), but the entire book is online: http://webdam.inria.fr/Alice/

[senderista]

Another excellent DB textbook covering both theory and implementation is Weikum & Vossen:

https://www.google.com/books/edition/_/wV5Ran71zNoC?hl=en&gb...

In case you can't afford to donate $150 to Elsevier: https://www.dropbox.com/scl/fi/r0fros5y2kzeqv57v7myz/Transac...