Lincoln Yeoh <lyeoh(at)pop(dot)jaring(dot)my> writes:
> To me what would also be useful would be synchronous notifications.
AFAICS this exists already --- or if it doesn't, that's a client-library
deficiency, not something to solve by inventing more SQL functions.
The form you propose cannot work anyway since NOTIFY events are not
delivered mid-transaction.
regards, tom lane