Re: Add parameter jit_warn_above_fraction

Peter Geoghegan <pg(at)bowt(dot)ie> writes:
> On Tue, Mar 29, 2022 at 1:06 PM David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
>> That means that even if the total execution time of a plan was a true
>> reflection of the total estimated plan cost, then the fraction of time
>> spent (as is measured by jit_warn_above_fraction) doing JIT would
>> entirely depend on the number of expressions to compile. Of course,
>> the planner's not that good, but does that not indicate that the JIT
>> costing should really account for the number of expressions and not
>> just the total plan cost?

> That's a good point.

I think David's questions are sufficiently cogent and difficult
that we should not add jit_warn_above_fraction at this time.
Maybe we'll eventually decide it's the best we can do; but I do
not think we have a problem there that's so pressing that we need
to rush out a partially-baked bandaid. Especially not at the
tail end of the development cycle, with not much time to gain
experience with it before we ship.

regards, tom lane