Practical book that goes into enough details of what happens under the hood while staying engaging and not too academic. Then it provides extensive references at the end of every chapter for further deep-dive. I personally consider it a must read for anyone running production system.
Here in Martin's word why he wrote such book: https://martin.kleppmann.com/2014/09/15/writing-a-book.html
HN: https://news.ycombinator.com/item?id=15428526