For database schema changes, here is the standard practice: - You have version 1 of the software, supporting schema A. - You deploy a version 2 supporting both schema A and new schema B. Both versions coexist until the deployment iis complete and all version 1 instances are stopped. During all this time the database is still on schema A, this is fine because your instances, both version 1 and 2, support schema A.
- Now you do the schema upgrade. This is fine because your instances, now all runnning version 2, support schema B
- At last, if you wish you can now deploy a version 3, dropping the support for schema A.
Good job !