On Fri, Apr 4, 2025 at 12:11 PM Melanie Plageman <melanieplage...@gmail.com> wrote: > That being said, long-running transactions are a problem for > autovacuum in general. Even if you track this stat you are proposing > about heap fetches by index only scans, you won't know if the long > running transaction is over and thus if it makes sense to try and > trigger an autovacuum for that table again anyway.
This. It would be really useful to have some kind of a system for figuring out when -- in terms of XIDs -- we ought to vacuum which table. I think that's a hard problem, but it would help a lot of people. I do not think the approach in the proposed patch is correct at all. The proposed new check would have exactly the same problem as the existing one -- this could easily trigger vacuuming at a time when the relevant tuples can't yet be made all-visible, in which case we'd just do a lot of VACUUM work for nothing. That's already a problem with autovacuum in some scenarios, and I bet this would be way worse. -- Robert Haas EDB: http://www.enterprisedb.com
