What is consistency anyway...discussed is the difference between partitioned vs global consensus.
Intro...
> Over the past decade, application developers have discovered that it is extremely difficult to build bug-free applications over database systems that do not guarantee consistency. This has led to a surprising shift in momentum, with many of the more recently released systems claiming to guarantee consistency (and be CP from CAP). Included in this list of newer systems are: Spanner (and its Cloud Spanner counterpart), FaunaDB, CockroachDB, and YugaByte. In this post, we will look more deeply into the consistency claims of these four systems (along with similar systems) and note that while some do indeed guarantee consistency, way too many of them fail to completely guarantee consistency. We will trace the failure to guarantee consistency to a controversial design decision made by Spanner that has been tragically and imperfectly emulated in other systems.
Abadi blogpost page 
Also see
PACELC theorem page