ALTER TABLE a
  ADD CONSTRAINT a_b_id_desc_fkey
  FOREIGN KEY (b_id_desc) REFERENCES b(id_desc)
  DEFERRABLE INITIALLY DEFERRED
  NOT VALID;

ALTER TABLE b
  ADD CONSTRAINT b_a_id_desc_fkey
  FOREIGN KEY (a_id_desc) REFERENCES a(id_desc)
  DEFERRABLE INITIALLY DEFERRED
  NOT VALID;
