If Eventual Consistency Seems Hard, Wait Till You Try MVCC

“One of the great lies about NoSQL databases is that they’re simple. Simplicity done wrong makes things a lot harder and more complicated to develop and operate. Programmers and operations staff end up reimplementing (badly) things the database should do…”

http://www.xaprb.com/blog/2014/12/08/eventual-consistency-simpler-than-mvcc/