On 2022-12-28 16:37:27 -0800, Peter Geoghegan wrote: > On Wed, Dec 28, 2022 at 4:20 PM Andres Freund <and...@anarazel.de> wrote: > > > Theoretically this is an old issue that dates back to commit > > > 699bf7d05c, as opposed to an issue in the page-level freezing patch. > > > But that's not really true in a real practical sense. In practice the > > > calls to TransactionIdDidCommit() will happen far more frequently > > > following today's commit 1de58df4fe (since we're using OldestXmin as > > > the cutoff that gates performing freeze_xmin/freeze_xmax processing -- > > > not FreezeLimit). > > > > Hm. But we still only do the check when we actually freeze, rather than just > > during the pre-check in heap_tuple_should_freeze(). So we'll only incur the > > increased overhead when we also do more WAL logging etc. Correct? > > Yes, that's how it worked up until today's commit 1de58df4fe. > > I don't have strong feelings about back patching a fix, but this does > seem like something that I should fix now, on HEAD. > > > Hm. I dimply recall that we had repeated cases where the hint bits were set > > wrongly due to some of the multixact related bugs. I think I was trying to > > be > > paranoid about not freezing stuff in those situations, since it can lead to > > reviving dead tuples, which obviously is bad. > > I think that it's a reasonable check, and I'm totally in favor of > keeping it (or something very close, at least).
I don't quite follow - one paragraph up you say we should fix something, and then here you seem to say we should continue not to rely on the hint bits?
