Re: Planner hints in Postgresql

The larger question to answer first is whether we want to implement

> something that is deterministic...
>
> How about just dropping the whole concept of "hinting" and provide a way
> for
> someone to say "use this plan, or die trying." Maybe require it be used in
> conjunction with named PREPAREd statements:
>

You mean taking away the entire concept of query planning and cost
estimation? Thats like replacing the optimizer with DBA decision and I am
not at all comfortable with that idea. That are only my thoughts though.

>
> PREPARE s1 (USING /path/to/plan_def_on_server_or_something_similar) AS
> SELECT ...;
>
> Aside from whole-plan specification I can definitely see where join/where
> specification could be useful if it can overcome the current limitation of
> not being able to calculate inter-table estimations.
>

Prepare plans use a generic plan for the execution. Replacing it with a
totally user defined plan does not seem to be clean.

The crux is that IMHO planner hints are a bad way of trying to circumvent
the need for cross-column statistics. We should do cross-column statistics
done and ignore planner hints completely.

Regards,

Atri

--
Regards,

Atri
*l'apprenant*