NoSQL data management systems

In the last decade, a new class of data management systems collectively called NoSQL systems emerged and are now intensively developed. The main feature of these systems is that they abandon the relational data model and the SQL, do not fully support ACID transactions, and use distributed architecture (even though there are non-distributed NoSQL systems as well). As a result, such systems outperform the conventional SQL-oriented DBMSs in some applications; in addition, such systems are highly scalable under increasing workloads and huge amounts of data, which is important, in particular, for Web applications. Unfortunately, the absence of transactional semantics imposes certain constraints on the class of applications where NoSQL systems can be effectively used and the choice of a particular system significantly depends on the application. In this paper, a review of the main classes of NoSQL data management systems is given and examples of systems and applications where they can be used are discussed.