On Thu, Sep 29, 2022 at 07:51:47PM -0400, Bruce Momjian wrote: > On Thu, Sep 29, 2022 at 07:46:18PM -0400, Tom Lane wrote: > > Agreed, but dealing with uncertainty in those numbers is an enormous > > task if you want to do it right. "Doing it right", IMV, would start > > out by extending all the selectivity estimation functions to include > > error bars; then we could have error bars on rowcount estimates and > > then costs; then we could start adding policies about avoiding plans > > with too large a possible upper-bound cost. Trying to add such > > policy with no data to go on is not going to work well. > > > > I think Peter's point is that a quick-n-dirty patch is likely to make > > as many cases worse as it makes better. That's certainly my opinion > > about the topic. > > Agreed on all points --- I was thinking error bars too.
Actually, if we wanted to improve things in this area, we should have a set of queries that don't chose optimal plans we can test with. We used to see them a lot before we had extended statistics, but I don't remember seeing many recently, let alone a collection of them. I guess that is good. -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com Indecision is a decision. Inaction is an action. Mark Batterson
