What is the difference between relational and non-relational databases and when should you choose which?

Relational databases store information in the form of tables with rows and columns, where strict connections are established between data through foreign keys. They are well-suited for working with structured data and complex relationships, and guarantee strict consistency through the support of ACID standards.

Non-relational databases offer flexible storage models, such as JSON documents, key-value pairs, graphs, or wide columns. They were created to scale across multiple servers and work with unstructured or semi-structured data where the document structure can change frequently.

The choice between these types of systems depends on the specifics of the project and the nature of the load. If an application requires complex financial calculations, strict reporting, and reliable relationships, a relational database will be the best choice. If you need to process huge streams of logs, user sessions, or a product catalog with arbitrary characteristics, NoSQL databases will provide better speed and scalability.

To make the right choice of the technology stack, it is recommended to evaluate the following factors: