Though each instance migration is done in one logical transaction, the migration tool can undo the entire migration any time. A specific migration run is identified by a migration ID. The migration tool uses the PI_MIGRATION_INFO and PI_MIGRATION_DETAIL tables to undo all the migrated instances of a particular run.
It is also possible to undo the migration of a specific process instance. Whenever a migrated instance is restored to its original state using the "undo" operation, the status of the migrated instance is marked as "undo" so that it cannot be restored again. However, an instance which is already restored can be migrated again using a separate run.
