On Fri, Nov 1, 2024 at 5:39 PM Masahiko Sawada <sawada.m...@gmail.com> wrote: > > I think we agreed with what the patches proposed by Melanie do, so > let's focus on these patches on this thread. We can add other > information later if we need.
Thanks for the feedback and input. So, currently what I have is a line for updates to the visibility map: visibility map: 5 pages set all-visible, 4 pages set all-frozen. Because this patch set is a prerequisite for the work I proposed over in [1], Andres happened to review this patch in the course of reviewing the larger patch set. He brought up yet a different perspective that I hadn't thought of [2]. He says: > Hm. Why is it interesting to log VM changes separately from the state changes > of underlying pages? Wouldn't it e.g. be more intersting to log the number of > empty pages that vacuum [re-]discovered? I've a bit hard time seeing how a > user could take advantage of this. I think he is saying that the updates to the VM to set pages all-frozen belong with the "frozen" line of vacuum log output: frozen: 0 pages from table (0.00% of total) had 0 tuples frozen Personally, I do think pages set all-visible/all-frozen in the VM is interesting to users -- when determining how much useful work a given vacuum did. And the "frozen" line is really about freezing tuples -- there can be pages with newly frozen tuples that aren't set all-frozen in the VM and pages set all-frozen in the VM that don't have newly frozen tuples (because they are empty). I do agree that logging the number of empty pages vacuum rediscovered could be useful (maybe in a "freespace" prefixed line about freespace and empty pages vacuum found). But, I don't think that is a reason not to add VM updates to the vacuum log output. So, after all of the discussion on this thread, I propose the existing vacuum log output (as on master) with the addition of one line about pages newly set all-visible/all-frozen by this vacuum: visibility map: 5 pages set all-visible, 4 pages set all-frozen. - Melanie [1] https://www.postgresql.org/message-id/flat/CAAKRu_ZF_KCzZuOrPrOqjGVe8iRVWEAJSpzMgRQs%3D5-v84cXUg%40mail.gmail.com [2] https://www.postgresql.org/message-id/ctdjzroezaxmiyah3gwbwm67defsrwj2b5fpfs4ku6msfpxeia%40mwjyqlhwr2wu
