This post by Peter Bailis is a must read. “Safety and Liveness: Eventual consistency is not safe” [1].
[1] http://www.bailis.org/blog/safety-and-liveness-eventual-consistency-is-not-safe/An extreme TL;DR of this is.
1) In an eventually consistent system, when all the nodes will agree again after a partition?
2) In an eventually consistent system, HOW the nodes will agree about inconsistencies?
3) In immediately consistent systems, when I’m no longer able to write? When I’m no longer able to read?
Basically:
“1” is time (or more practically, conditions needed to merge).
“2” is safety (or more practically, merge strategy).
“3” is availability (or more practically, how much of the system can be down, for me to be still able to write and read).
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