Can you give an example when data denormalization is used in a database?

Denormalization is the deliberate duplication of data in a database to improve read performance at the cost of increased update complexity.

Example of use: In an online store, to speed up the display of order information, the customer's name and address can be stored directly in the orders table, even though this data already exists in the customers table. This allows for quick retrieval of all order information without complex JOIN queries.

This approach is useful when data is read much more frequently than it is updated, and response speed is important.