Re: generalizing the planner knobs

Neil Conway <neilc(at)samurai(dot)com> writes:
> ... ISTM that a simple improvement to what we have now
> would allow for a wider range of planner hints with only minor changes:
> we could replace the enable_XXX variables with a set of variables that
> would add an arbitrary constant to the estimated cost of each type of
> query node. (Alternatively, an arbitrary multiplier could be specified;
> I'm not sure which would be better.)

I think the multiplier would be better, because it'd avoid the problem
you mention later that useful values would be dependent on the planner's
cost units. Also, one could sanely allow a multiplier less than one,
so as to favor instead of penalize a particular plan type.

regards, tom lane