Re: Planner hints in Postgresql
От | Atri Sharma |
---|---|
Тема | Re: Planner hints in Postgresql |
Дата | |
Msg-id | CAOeZVieod1S4C42r8Zq3341j=AxhSYDagO1P=sbqBUeEfyMoVQ@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: Planner hints in Postgresql (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
On Mon, Mar 17, 2014 at 10:54 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Atri Sharma <atri.jiit@gmail.com> writes:
> On Mon, Mar 17, 2014 at 9:45 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:>> Possibly worth noting is that in past discussions, we've concluded thatAnd forcing a plan to be used *isn't* that? Please re-read the older
>> 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?
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
--
Regards,
Atri
l'apprenant
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