On Fri, Feb 4, 2022 at 10:44 PM Peter Geoghegan <p...@bowt.ie> wrote: > Right - it's practically inevitable that you'll need an > anti-wraparound VACUUM to advance relfrozenxid right now. Technically > it's possible to advance relfrozenxid in any VACUUM, but in practice > it just never happens on a large table. You only need to get unlucky > with one heap page, either by failing to get a cleanup lock, or (more > likely) by setting even one single page all-visible but not all-frozen > just once (once in any VACUUM that takes place between anti-wraparound > VACUUMs).
Minor correction: That's a slight exaggeration, since we won't skip groups of all-visible pages that don't exceed SKIP_PAGES_THRESHOLD blocks (32 blocks). -- Peter Geoghegan
