What is the purpose of performing database migrations and in what cases are they usually used?

Database migrations are a mechanism for managing changes to the database structure (such as adding tables, modifying columns, creating indexes) in a controlled and sequential manner. The goal of migrations is to ensure consistency of the database schema across different environments (development, testing, production) and to simplify the process of updating the database when application requirements change.

Migrations are typically used in the following cases:

• When adding new features that require changes to the database structure.
• When fixing errors in the data structure.
• When refactoring the schema for optimization.

Example: In Android with Room, migrations help smoothly update the local database without losing user data when updating the application.