Обсуждение: remove autoanalyze corner case
(new thread from [0]) On Fri, Apr 03, 2026 at 02:13:16PM -0500, Sami Imseih wrote: >> * I noticed that if autovacuum decides to force a vacuum for >> anti-wraparound purposes, it might also decide to analyze the table even if >> autovacuum is disabled for it. AFAICT this is accidental, but since it's >> behaved this way since commit 48188e1621 (2006) [0], I am slightly worried >> that this bug may have become a feature. In 0002, I separated this edge >> case in the code and added a comment, and I intend to start a new thread >> about removing it. > > hmm yeah, I think this just needs to be documented clearly. I always > thought it was expected for auto-analyze to run in this case, and I don't > see why it shouldn't. If this needs to be clarified in docs, we should > do that in a separate discussion. Well, autoanalyze only runs in this case if autovacuum is disabled via the table's autovacuum_enabled reloption and _not_ disabled via the autovacuum or track_counts GUCs. I think this is pretty clearly unintentional, as I can find no mention in the code, archives, or docs. And unless I'm missing something, it's completely unnecessary. So IMHO we should just remove it. [0] https://postgr.es/m/CAA5RZ0sCRjH3xkHFdSXnKysdMZXFyaS_094%2BK-O_rr4Fkmwc%3DQ%40mail.gmail.com -- nathan
Вложения
On Fri, Apr 3, 2026 at 10:55 PM Nathan Bossart <nathandbossart@gmail.com> wrote: > > (new thread from [0]) > > On Fri, Apr 03, 2026 at 02:13:16PM -0500, Sami Imseih wrote: > >> * I noticed that if autovacuum decides to force a vacuum for > >> anti-wraparound purposes, it might also decide to analyze the table even if > >> autovacuum is disabled for it. AFAICT this is accidental, but since it's > >> behaved this way since commit 48188e1621 (2006) [0], I am slightly worried > >> that this bug may have become a feature. In 0002, I separated this edge > >> case in the code and added a comment, and I intend to start a new thread > >> about removing it. > > > > hmm yeah, I think this just needs to be documented clearly. I always > > thought it was expected for auto-analyze to run in this case, and I don't > > see why it shouldn't. If this needs to be clarified in docs, we should > > do that in a separate discussion. > > Well, autoanalyze only runs in this case if autovacuum is disabled via the > table's autovacuum_enabled reloption and _not_ disabled via the autovacuum > or track_counts GUCs. I think this is pretty clearly unintentional, as I > can find no mention in the code, archives, or docs. And unless I'm missing > something, it's completely unnecessary. So IMHO we should just remove it. > > [0] https://postgr.es/m/CAA5RZ0sCRjH3xkHFdSXnKysdMZXFyaS_094%2BK-O_rr4Fkmwc%3DQ%40mail.gmail.com > AFAICS, near misses on wraparound in and of itself have no correlation with statistical changes in your data, so I'd agree it isn't necessary, and the fact that it behaves differently in this more narrow case than it would in the more general case, when these two cases are (as far as I've ever known) supposed to behave the same way, I'd be +1 to remove this. Robert Treat https://xzilla.net
On 2026-Apr-04, Robert Treat wrote: > AFAICS, near misses on wraparound in and of itself have no correlation > with statistical changes in your data, so I'd agree it isn't > necessary, and the fact that it behaves differently in this more > narrow case than it would in the more general case, when these two > cases are (as far as I've ever known) supposed to behave the same way, > I'd be +1 to remove this. Yeah, that matches my impression. +1 to remove it. -- Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/ "La verdad no siempre es bonita, pero el hambre de ella sí"
>> AFAICS, near misses on wraparound in and of itself have no correlation >> with statistical changes in your data, so I'd agree it isn't >> necessary, and the fact that it behaves differently in this more >> narrow case than it would in the more general case, when these two >> cases are (as far as I've ever known) supposed to behave the same way, >> I'd be +1 to remove this. > Yeah, that matches my impression. +1 to remove it. That is fine with me also. The patch LGTM. -- Sami
On Sat, Apr 4, 2026 at 11:55 AM Nathan Bossart <nathandbossart@gmail.com> wrote: > Well, autoanalyze only runs in this case if autovacuum is disabled via the > table's autovacuum_enabled reloption and _not_ disabled via the autovacuum > or track_counts GUCs. I think this is pretty clearly unintentional, as I > can find no mention in the code, archives, or docs. And unless I'm missing > something, it's completely unnecessary. So IMHO we should just remove it. +1. I think it might be better to mention this in the documentation to make the behavior explicit. What do you think about stating that an anti-wraparound autovacuum does not perform an ANALYZE, like in the attached patch? -- Best regards, Shinya Kato NTT OSS Center
Вложения
> > Well, autoanalyze only runs in this case if autovacuum is disabled via the > > table's autovacuum_enabled reloption and _not_ disabled via the autovacuum > > or track_counts GUCs. I think this is pretty clearly unintentional, as I > > can find no mention in the code, archives, or docs. And unless I'm missing > > something, it's completely unnecessary. So IMHO we should just remove it. > > +1. I think it might be better to mention this in the documentation to > make the behavior explicit. What do you think about stating that an > anti-wraparound autovacuum does not perform an ANALYZE, like in the > attached patch? +1 to the additional documentation. a small nit: We can just say "skipped" and not "still skipped". -- Sami
On Mon, Apr 6, 2026 at 7:28 AM Sami Imseih <samimseih@gmail.com> wrote: > > +1. I think it might be better to mention this in the documentation to > > make the behavior explicit. What do you think about stating that an > > anti-wraparound autovacuum does not perform an ANALYZE, like in the > > attached patch? > > +1 to the additional documentation. > > a small nit: We can just say "skipped" and not "still skipped". Thanks, I've fixed it. -- Best regards, Shinya Kato NTT OSS Center
Вложения
Committed. I left out the documentation updates for now. -- nathan