Re: Bitmap scan seem like such a strange choice when "limit 1"

Klaudie Willis <Klaudie(dot)Willis(at)protonmail(dot)com> writes:
> I'd like to add, that when I do the same query DIRECTLY on the bigtable_y2020 (instead of the partition parent) it does change to "index scan" again.

Yeah. I think the issue here is that add_paths_to_append_rel only
considers cheapest-total paths for the member relations. Seeing
that it's already considering a slightly ridiculous number of
parallelization options, I'm hesitant to throw in cheapest-startup
considerations as well, for fear of blowing out planning time.

Maybe the right way to improve this is to bypass add_paths_to_append_rel
entirely when there's exactly one surviving child rel, and make it
just use all the surviving paths for that child.

regards, tom lane