On Mon, Dec 6, 2021 at 6:04 PM Euler Taveira <eu...@eulerto.com> wrote: > > On Mon, Dec 6, 2021, at 3:35 AM, Dilip Kumar wrote: > > On Mon, Dec 6, 2021 at 6:49 AM Euler Taveira <eu...@eulerto.com> wrote: > > > > On Fri, Dec 3, 2021, at 8:12 PM, Euler Taveira wrote: > > > > PS> I will update the commit message in the next version. I barely changed > > the > > documentation to reflect the current behavior. I probably missed some > > changes > > but I will fix in the next version. > > > > I realized that I forgot to mention a few things about the UPDATE behavior. > > Regardless of 0003, we need to define which tuple will be used to evaluate > > the > > row filter for UPDATEs. We already discussed it circa [1]. This current > > version > > chooses *new* tuple. Is it the best choice? > > But with 0003, we are using both the tuple for evaluating the row > filter, so instead of fixing 0001, why we don't just merge 0003 with > 0001? I mean eventually, 0003 is doing what is the agreed behavior, > i.e. if just OLD is matching the filter then convert the UPDATE to > DELETE OTOH if only new is matching the filter then convert the UPDATE > to INSERT. Do you think that even we merge 0001 and 0003 then also > there is an open issue regarding which row to select for the filter? > > Maybe I was not clear. IIUC we are still discussing 0003 and I would like to > propose a different default based on the conclusion I came up. If we merged > 0003, that's fine; this change will be useless. If we don't or it is optional, > it still has its merit. > > Do we want to pay the overhead to evaluating both tuple for UPDATEs? I'm still > processing if it is worth it. If you think that in general the row filter > contains the primary key and it is rare to change it, it will waste cycles > evaluating the same expression twice. It seems this behavior could be > controlled by a parameter. >
I think the first thing we should do in this regard is to evaluate the performance for both cases (when we apply a filter to both tuples vs. to one of the tuples). In case the performance difference is unacceptable, I think it would be better to still compare both tuples as default to avoid data inconsistency issues and have an option to allow comparing one of the tuples. -- With Regards, Amit Kapila.
