All databases are multi-model…

Amongst the marketing material on the virtues of different database types there is an amber glowing and that some keep to themselves for want of not rocking the boat. That beacon beams the light of knowledge that all databases are multi-model bar for thinking different.

But what is a multi-model database?

There are many descriptions of a multi-model database but we focus here on databases that can be queried as a graph database or a relational database. For our purpose though, it would not matter if the database was a document store database. All databases can be viewed the same way. It is the query language over the database that makes the difference, and the way the database is conceptualised, and I will explain.

Conceptual Models

At the top of this article are three views of parts of the same underlying model. The top diagram is an Object-Role Model. On the left is an Entity Relationship Diagram and on the right a Property Graph Schema.

Graph database vendors extol the virtues of property graph schemas and a dedicated graph query languages that range over what are called graphs. Relational database vendors extol the virtues of a relational model, as per the entity relationship diagram.