Martijn van Oosterhout <kleptog@svana.org> writes:
> I think you're running into a small limitation of set functions here.
> If you look at nodeFunctionScan.c that handles this, you can see that
> the code is written in such a way as to collect all the tuples first
> before returning anything.
I don't think Thomas intended to go through nodeFunctionScan, so this
needn't apply to him.
> Not sure why it does that,
plpgsql and similar languages will return a tuplestore anyway, so it has
to handle that case, and it was convenient to make all the cases look
alike for starters. Nobody's yet gone back to improve it for the case
of languages that return a tuple per call.
regards, tom lane