Re: Planner hints in Postgresql

On Mon, Mar 17, 2014 at 10:54 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Atri Sharma <atri(dot)jiit(at)gmail(dot)com> writes:
> > On Mon, Mar 17, 2014 at 9:45 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> Possibly worth noting is that in past discussions, we've concluded that
> >> the most sensible type of hint would not be "use this plan" at all, but
> >> "here's what to assume about the selectivity of this WHERE clause".
> >> That seems considerably less likely to break than any attempt to
> directly
> >> specify plan details.
>
> > Isnt using a user given value for selectivity a pretty risky situation as
> > it can horribly screw up the plan selection?
>
> And forcing a plan to be used *isn't* that? Please re-read the older
> threads, since you evidently have not.
>
>
I never said that we force a plan to be used. I just said that we should
increase the preference for a user given plan and not interfere in the cost
estimation of the other potential plans and the evaluation of the final
selected plan.

Regards,

Atri

--
Regards,

Atri
*l'apprenant*