The chapter discusses the necessity for data modeling in NoSQL world. The NoSQL data modeling is a huge challenge because one of the main features of NoSQL databases is that they are schema-free, that is they allow data manipulation without the need for the previous modeling or developing an entity-relationship (ER) or similar model. Although the absence of a schema can be an advantage in some situations, with the increase in the number of NoSQL database implementations, it appears that the absence of a conceptual model can be a source of substantial problems. In order to better understand the need for data modeling in NoSQL databases, first the basic structure of an ER model and an analysis of its limitations are summarized, especially regarding an application in NoSQL databases. The concept and Object modeling notation is presented as one of the possible solutions for data modeling in NoSQL databases.
TopData Modeling In Relational Databases
The purpose of this chapter is to explain the main concepts of ER modeling so that readers (especially those without prior knowledge of ER modeling) can more easily understand the need for modeling in NoSQL databases and a COMN model (“The Concept and Object Modeling Notation”).
The ER model is the primary model used in modeling relational databases. ER modeling involves a top-down approach to database design that starts by identifying important data that comprises entities and relationships between the data represented by the model. Then details are added, such as the information needed on the entities and relationships, called attributes, as well as constraints on the entities, relationships, and attributes.
An ER model is a detailed, logical presentation of data of an organization or a business field. It is expressed in terms of entities in the business environment, relationships (associations) between these entities, and attributes (properties) of both the entities and the relationships. An entity-relationship diagram represents an ER model, also called an ER diagram or ERD (Hoffer, Ramesh & Topi, 2011).
The ER model quickly became popular because of its complementarity with the relational data model concepts, and after decades of use, the ER model remains the leading approach in conceptual data modeling. Its popularity results from factors such as relative ease of use, support by CASE (computer-aided software engineering) tools, and the widespread belief that entities and relationships are natural modeling concepts in the real world.