Google Cloud Platform for Developers

Maintaining consistency

Maintaining consistency in a highly distributed environment presents an interesting challenge. To state the problem, how can a distributed system ensure that, under any conditions, all observers will see the latest changes made at any other point in the system? The instant a change is made to the data in one location, every other member of the system must be made aware of that change so that no observer sees results that are out-of-date. Furthermore, the system must prevent two parties from modifying data at the same time, or have a way to determine which of the two parties was first.

Generally, NoSQL solutions that attempt to solve this issue do so at a significant performance cost as they must fully lock the data ...