Simon Riggs <simon.ri...@enterprisedb.com> writes: > On Fri, 16 Sept 2022 at 15:26, Tom Lane <t...@sss.pgh.pa.us> wrote: >> You cannot >> do that, at least not without checking that the originating >> transaction has no snapshots that could see the older row version.
> I'm saying this is possible only AFTER the end of the originating > xact, so there are no issues with additional snapshots. I see, so the point is just that we can prune even if the originating xact hasn't yet passed the global xmin horizon. I agree that's safe, but will it fire often enough to be worth the trouble? Also, why does it need to be restricted to certain shapes of HOT chains --- that is, why can't we do exactly what we'd do if the xact *were* past the xmin horizon? regards, tom lane