Re: Planner creating ineffective plans on LEFT OUTER joins

Ron Mayer <rm_pg@cheapcomplexdevices.com> writes:
> Couldn't the planner itself make a good guess if it should
> keep trying based on the estimated cost?

> if (the_best_plan_I_found_so_far_looks_like_itll_take_an_hour)
>    keep_optimizing_for_a_few_minutes
> if (the_best_plan_I_found_so_far_looks_like_itll_take_0.01ms)
>    stop_planning_and_run_with_it

You're operating on a mistaken assumption, which is that we generate a
complete plan and then generate another.  The places where we'd actually
be doing something with an effort variable are usually dealing with
small parts of plans, or even with preparatory calculations before we've
got anything plan-like at all.  They haven't got a sufficiently holistic
view of what's happening to apply a rule like the above.
        regards, tom lane