On Mon, Mar 6, 2023 at 2:38 PM Önder Kalacı <onderkal...@gmail.com> wrote: > I was going through the thread and patch, I noticed that in the initial version, we were depending upon the planner to let it decide whether index scan is cheaper or not and which index to pick. But in the latest patch if a useful index exists then we chose that without comparing the cost of whether it is cheaper than sequential scan or not. Is my understanding correct? What is the reason for the same, one reason I could see while looking into the thread is that we can not just decide once whether the index scan is cheaper or not because that decision could change in the future but isn't that better than never checking whether index scan is cheaper or not. Because in some cases where column selectivity is high like 80-90% then the index can be very costly due to random page fetches. So I think we could easily produce regression in some cases, have we tested those cases?
Let me if I am missing something. -- Regards, Dilip Kumar EnterpriseDB: http://www.enterprisedb.com
