CREATE TABLE public.notification(
  id_user integer NOT NULL,
  event text NOT NULL,
  target_id integer NOT NULL,
  CONSTRAINT notification_primary PRIMARY KEY (id_user, event, target_id)
);
ALTER TABLE public.notification ADD CONSTRAINT id_user_fk FOREIGN KEY (id_user)
REFERENCES public.user_info (id) MATCH FULL
ON DELETE CASCADE ON UPDATE CASCADE;
CREATE INDEX notification_idx ON public.notification
  USING btree(event);