A database cloned for an upgrade rehearsal began from a valid source snapshot. Later source-side schema and reference-data changes still had to be applied to the test target before application testing could use a comparable baseline.

The target was not empty. It already contained part of the desired …

A newly created business record failed with ORA-00001 on a primary key. That was unexpected because the application generated the key from an Oracle sequence. The log resolved the contradiction: the generated value already belonged to an older row that had arrived with the migrated data.

This was …