https://medium.com/@jonathangfischoff/what-should-a-postgresql-migrator-do-47fd34804be

One of the tricky parts of programming against a database is ensuring the database schema in production is compatible with the code. A delicate dance must occur between modifications to the database and deployment of new versions of an application. Even if we consider the simple case, deploying with downtime, it still requires effort to ensure the application can operate without errors.