Re: Todo: Teach planner to evaluate multiple windows in the optimal order

I wrote:
> it might be worthwhile to "zoom in" with more measurements, but haven't
done that yet.

I've attached the script and image for 1 million / random / varying the mod
by quarter-log intervals. Unfortunately I didn't get as good results as
yesterday. Immediately going from mod 1 to mod 2, sort pushdown regresses
sharply and stays regressed up until 10000. The tiebreaker patch helps but
never removes the regression.

I suspect that I fat-fingered work_mem yesterday, so next I'll pick a
badly-performing mod like 32, then range over work_mem and see if that
explains anything, especially whether L3 effects are in fact more important
in this workload.

--
John Naylor
EDB: http://www.enterprisedb.com