Re: *_collapse_limit, geqo_threshold

On Thursday 09 July 2009 17:37:41 Kevin Grittner wrote:
> Resending to list due to failure:
> 451 4.3.5 Server configuration problem
>
> Joshua Tolley <eggyknap(at)gmail(dot)com> wrote:
> > Entire stored plans, or predetermined seeds for GEQO's random number
> > generator all boil down to saying, "I want you to use this plan
> > henceforth and forever."
>
> A predetermined seed for geqo's random number generator only
> guarantees that you get the same plan for the same query as long as
> the statistics remain the same. After the next ANALYZE, you may still
> get a different plan.
>
> > Do we know that GEQO plans are, in reality, less stable than than
> > usual planner?
Yes definitely. I.e. in the referenced schema (somewhere else in the thread) I
even have queries which fail to plan only sometimes.

Andres