Do you prefer to use relational or non-relational data storage systems?

The choice between relational and non-relational data storage systems depends on the specific requirements of the project.

Relational databases (e.g., PostgreSQL, MySQL) are well-suited when strict data structure, transaction support, and complex SQL queries are important. They ensure data integrity and are convenient for systems with clearly defined schemas.

Non-relational databases (e.g., MongoDB, Redis) are more flexible, allow storing data without a strict schema, scale well, and are suitable for projects with rapidly changing data structures or large volumes of unstructured information.

In practice, I choose:

• Relational databases for financial applications where consistency is crucial.
• Non-relational for caching, logs, or when data has a flexible structure.

Thus, the preference depends on the task, and often both types of databases are used in a project for different purposes.