A very common problem I have seen in distributed applications is that the database is treated as an internal part of the application. As soon as you have a sepa

A very common problem I have seen in distributed applications is that the database is treated as an internal part of the application. As soon as you have a separate server running a database (basically most modern setups that don't use SQLite) you have a distributed system, and the database is an external dependency -- just like, say, Facebook/Google API you use for SSO. It becomes even more clear if your system has several independent services. Once you accept this, the database schema becomes just yet another API contract to accept and respect, with all the same mechanisms to ensure compatibility -- versioning, integration tests etc.