On Mon, Mar 6, 2023 at 4:45 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Mon, Mar 6, 2023 at 4:18 PM Dilip Kumar <dilipbal...@gmail.com> wrote: > > > > 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, > > > > Yes, your understanding is correct. The main reason is that we don't > have an agreement on using the internal planner APIs for apply. That > will be a long-term maintenance burden. See discussion around email > [1]. So, we decided to use the current infrastructure to achieve index > scans during apply when publisher has replica identity full. This will > still be win in many cases and we are planning to provide a knob to > disable this feature. > > [1] - https://www.postgresql.org/message-id/3466340.1673117404%40sss.pgh.pa.us
Okay, this makes sense, so basically, in "replica identify full" case instead of doing the default sequence scan we will provide a knob to either choose index scan or sequence scan, and that seems reasonable to me. -- Regards, Dilip Kumar EnterpriseDB: http://www.enterprisedb.com