1. I think the order by pk frac limit plans had just to similar performance behaviour for me to bother. But afaics the main point of your proposal is not related to frac plans at all.
Right.
2. We can't expect the optimizers to simply yield better results by being given more options to be wrong. (Let me give a simple example:
This patch makes our lack of cross table cross column statistics worse. We give it more opportunity to pick something horrible.
I don't see the connection between cross column statistics and this bug I am fixing. Can you please elaborate?
3. I dislike, that this patch makes much harder to debug, why no partitionwise join is chosen.
Can you please elaborate more? How does my change make debugging harder?
