Conceptual modeling of a document-oriented NoSQL database

Massive databases or Big Data are generally managed by NoSQL systems. Most of these systems are schemaless, meaning that the schema is not predefined; it is provided as the database (DB) is fed. This property increases data flexibility. However, the absence of a schema is a major obstacle for expressing complex queries and for the semantic analysis of data. In our previous work [1], we proposed a process for extracting the logical schema of a document-oriented NoSQL DB; this schema allows to describe the structure of the data stored in the DB and thus facilitates query writing. But to understand the meaning of the data and its structure, a conceptual schema is the most appropriate tool, since it ignores the technical aspects linked to implementation. In this paper, we propose a process for transforming the logical schema of a DB into a UML-type conceptual schema. It shows the object classes and semantic links (association, composition and inheritance) contained in the DB. Based on Model Driven Architecture (MDA), our process relies on metamodels and a set of transformation rules to automatically produce the conceptual schema from the logical schema. We experimented our process using a medical application.