I have not read it personally, but I've seen 'How Query Engines Work' highly recommended several times before. I have a procrasinatory tab open to check it out some day.

https://leanpub.com/how-query-engines-work

Database Internals is also pretty good.

Seconding Database Internals - it's not just about "Internals of a database", as part 2 gets nitty gritty with the general problems of distributed systems, consensus, consistency, availability, etc. etc.

There is a quite-nice interactive browser dataviz here that shows you books similar to the themes, categories, and topics discussed in DDIA:

https://anvaka.github.io/greview/ddia/1/

Database Design for Mere Mortals by Ray Hernandez