On Wed, Jan 18, 2023 at 7:04 PM Andres Freund <and...@anarazel.de> wrote: > > You seem to be saying that it's a problem if we don't update reltuples > > -- an estimate -- when less than 2% of the table is scanned by VACUUM. > > But why? Why can't we just do nothing sometimes? I mean in general, > > leaving aside the heuristics I came up with for a moment? > > The problem isn't that we might apply the heuristic once, that'd be fine. But > that there's nothing preventing it from applying until there basically are no > tuples left, as long as the vacuum is frequent enough. > > As a demo: The attached sql script ends up with a table containing 10k rows, > but relpages being set 1 million.
I saw that too. But then I checked again a few seconds later, and autoanalyze had run, so reltuples was 10k. Just like it would have if there was no VACUUM statements in your script. -- Peter Geoghegan
