dmitry100

Воспользовался таким костылем разд

ALTER TABLE tickets
	DROP CONSTRAINT tickets_book_ref_fkey;

ALTER TABLE tickets
	ADD CONSTRAINT tickets_book_ref_fkey
	FOREIGN KEY (book_ref)
	REFERENCES bookings(book_ref)
	ON DELETE CASCADE;

ALTER TABLE ticket_flights
	DROP CONSTRAINT ticket_flights_ticket_no_fkey;

ALTER TABLE ticket_flights
	ADD CONSTRAINT ticket_flights_ticket_no_fkey
	FOREIGN KEY (ticket_no)
	REFERENCES tickets(ticket_no)
	ON DELETE CASCADE;

Помогла статья: Настройка связи FOREIGN KEY/ON DELETE CASCADE в PostgreSQL