After some pauses in the middle, I finally finished Martin Kleppmann's book Designing Data-Intensive Applications.
In short, it's a great book on different aspects of data: storing data, transferring data, processing data, distributed systems etc. etc.
The writer was focusing on concepts rather than details of individual tools. Also he had a nice balance of theory and practise.
Each chapter has nice old-school map as TOC. For the total TOC, check out the cool poster.
