"Jaime Casanova" <systemguards(at)gmail(dot)com> writes:
>>> There's been some talk about prohibiting flattening if there are any
>>> volatile functions in the subselect's targetlist, but nothing's been
>>> done about that.
> BTW, can you think in a good name for a GUC for this?
I'm not in favor of a GUC for this; we should either do it or not.
If we do it, basically the response to anyone who complains about loss
of performance should be "fix your function to be marked stable or
immutable, as appropriate".
regards, tom lane