Re: BUG #5611: SQL Function STABLE promoting to VOLATILE

Robert Haas <robertmhaas@gmail.com> writes:
> In theory, the optimization Brian wants is possible here, right?  I
> mean, you could replace the functional call with a Param, and pull the
> Param out and make it an InitPlan.  Seems like that would generally be
> a win, if you figure to loop more than once and the execution cost of
> the function is not too tiny.

Yeah, possibly.  It would probably be difficult for the planner to
figure out where the cutover point is to make that worthwhile, though;
the point where you'd need to make the transformation is long before we
have any rowcount estimates.

I was about to suggest that Brian could make that happen manually
by writing ... FROM srf((SELECT expensive_func())) ... but I think
actually that will just amount to another way of disabling inlining.

            regards, tom lane