Backend Migrations

Database migrations are versioned files that define schema changes with upgrade and downgrade methods. Create migration files in directories like migrations/ or alembic/versions/ with up() and down() methods to safely modify tables, columns, and indexes while maintaining rollback capability.

Yes, rollback support is built into versioned migrations through down() methods that reverse schema changes. This enables safe deployment workflows where you can revert to a previous database state if issues arise.

Zero-downtime deployments require backwards-compatible schema changes applied in stages. Use migrations to add columns before removing old ones, deploy new code alongside schema changes, and coordinate application updates with schema evolution to minimize service disruption.

Migration frameworks like Alembic work across SQL databases by managing schema evolution through version-controlled migration files. They handle table creation, modification, removal, and constraint management across different database platforms through standardized upgrade and downgrade patterns.

Versioned migrations provide version control, repeatability, and rollback paths for schema changes. They track data integrity across deployments, enable team collaboration on schema evolution, and ensure consistent database state across environments.