Explain the differences between relational databases and non-relational data storage systems.

Relational databases (RDBMS) and non-relational (NoSQL) data storage systems differ in structure, storage methods, and data processing.

• Relational databases:

  • Store data in tables with a clearly defined schema (structure).
  • Use SQL language for queries.
  • Support transactions and ensure data integrity (ACID).
  • Well-suited for complex queries and linked data.
  • Examples: MySQL, PostgreSQL, Oracle.

• Non-relational databases:

  • Store data in various formats: documents, key-value, graphs, column stores.
  • Usually do not require a strict schema.
  • Can provide high scalability and performance.
  • Often used for large volumes of data and flexible structures.
  • Examples: MongoDB (documents), Redis (key-value), Cassandra (columnar).

The choice depends on project requirements: if strict structure and complex relationships are needed — relational; if flexibility and scalability — NoSQL.