Most of the applications we developers are working on are have to do with data. We are getting data from “outside world”, save it and pass further. And it does not matter how complex the domain is we always ask the next questions: How do I know for sure that my data is valid? How do I avoid errors in my system and do not inject it into other system? The answer is - better data modeling.

Effective communication requires getting definitions right. Very often the same word can have different meanings and lead to confusion. Good example of that would be term Consistency. In this article we will take a look at consistency in CAP and ACID and differences between them. Let’s start with defining CAP and ACID. CAP theorem is formulated by computer scientist Eric Brewer in 2000, and states that a distributed data store cannot simultaneously provide more than two out of the following three guarantees: