A migration script that finishes on a small staging dataset does not prove that production cutover is safe. A rehearsal measures actual timing, reveals incompatibilities and practices recovery before the change window.
Use a representative scale
Test volume, distribution, large records, nulls and old versions. If production data is not permitted, create a safe dataset with the same difficult characteristics.
Time each phase
Measure the snapshot, transformation, index build, validation and DNS or application switch. Add a buffer for slower storage and human coordination.
Define integrity checks
Compare counts, checksums, constraints, samples and critical business totals. A successful script exit does not prove the data is correct.
Test the application and integrations
Run reads, writes, background jobs, reports and downstream consumers. Many failures appear outside the new database schema.
Perform an actual rollback
Measure how the schema, data writes and traffic are restored and where the point of no return lies. An untested rollback is merely a wish.
This framework is an original editorial methodology developed by DigitalNow.