The current script cannot be executed if a resource has an history entry:

ERROR gnocchi oslo_db.exception.DBReferenceError: (psycopg2.IntegrityError) update or delete on table "resource" violates foreign key constraint "fk_rh_id_resource_id" on table "resource_history"
DEBUG [pifpaf.drivers] gnocchi-upgrade[71041] output: 2018-04-24 09:36:08.029 71041 ERROR gnocchi DETAIL:  Key (id)=(e8bce9ff-5c30-524c-87b8-bfb1dce7855b) is still referenced from table "resource_history".
DEBUG [pifpaf.drivers] gnocchi-upgrade[71041] output: 2018-04-24 09:36:08.029 71041 ERROR gnocchi  [SQL: 'UPDATE resource SET id=%(param_1)s, original_resource_id=%(original_resource_id)s WHERE resource.id = %(id_1)s'] [parameters: {'param_1': 'bd6eac67-c1e9-5da0-9979-a797d776039e', 'original_resource_id': 'historized_resource', 'id_1': UUID('e8bce9ff-5c30-524c-87b8-bfb1dce7855b')}] (Background on this error at: http://sqlalche.me/e/gkpj)

This drops and recreates the constraint at the end of the migration.