On 2022-05-27 11:48:45 -0700, Peter Geoghegan wrote: > On Fri, May 27, 2022 at 8:55 AM Andres Freund <and...@anarazel.de> wrote: > > > Anyway, how about if we clear this cache for subtrans whenever > > > TransactionXmin is advanced and cachedFetchSubXid precedes it? The > > > comments atop SubTransGetTopmostTransaction seem to state that we > > > don't care about the exact topmost parent when the intermediate one > > > precedes TransactionXmin. I think it should preserve the optimization > > > because anyway for such cases there is a fast path in > > > SubTransGetTopmostTransaction. > > > > There's not even a proof this does speed up anything useful! There's not a > > single benchmark for the patch. > > I find it hard to believe that there wasn't even a cursory effort at > performance validation before this was committed, but that's what it > looks like.
Yea. Imo this pretty clearly should be reverted. It has correctness issues, testing issues and we don't know whether it does anything useful.
