[zzzcpan]

Distributed systems. Consensus [0], CAP, PACELC theorems [1], CRDTs [2], maybe Chord DHT [3] for hash rings. Oh, and jepsen.io for actual database choices.

[0] https://en.wikipedia.org/wiki/Consensus_(computer_science)

[1] https://en.wikipedia.org/wiki/PACELC_theorem

[2] https://en.wikipedia.org/wiki/Conflict-free_replicated_data_...

[3] https://en.wikipedia.org/wiki/Chord_(peer-to-peer)