Discuss the role of backup and test databases in database redesign.

Typically, there are at least three different copies of the database schema used in database redesign: (1) a small test database for initial testing, (2) a large or full copy test database for further testing, and (3) the operational database itself. There must be a process to restore the test databases to their original state during the testing process so that tests can be rerun as needed. If it is not possible to use a full copy of a very large operational database for testing, an appropriate large-scale test version must be created and used.