A Comparison of Data Models and APIs of NoSQL Datastores

NoSQL datastore systems are a new generation of non-relational databases. More than fifty NoSQL systems have been already implemented, each with different characteristics --- especially, with different data models and different APIs to access the data. In this paper we describe and compare the data models and operations offered by a number of representative NoSQL datastores, which we have directly used while developing the SOS (Save Our Systems) and ONDM (Object-NoSQL Datastore Mapper) frameworks. We discuss how these NoSQL systems can be used to manage a database consisting of collections of objects. Furthermore, we report on some experimental results concerning the use of the various systems and the implementation of the data representations described in this paper.