BEGIN;
ALTER TABLE topology ADD CONSTRAINT topology_dev1_port1 UNIQUE (dev1, port1);
ALTER TABLE topology ADD CONSTRAINT topology_dev2_port2 UNIQUE (dev2, port2);
COMMIT;
BEGIN;
ALTER TABLE topology ADD CONSTRAINT topology_dev1_port1 UNIQUE (dev1, port1);
ALTER TABLE topology ADD CONSTRAINT topology_dev2_port2 UNIQUE (dev2, port2);
COMMIT;