On Tue, Feb 6, 2018 at 4:35 AM, Kyotaro HORIGUCHI <horiguchi.kyot...@lab.ntt.co.jp> wrote: >> It's starting to look like a timing effect indeed. > > It seems to be truncation skip, maybe caused by concurrent > autovacuum.
Good point, I'll also disable autovacuum on vactst. > See lazy_truncate_heap() for details. Updates of > pg_stat_*_tables can be delayed so looking it also can fail. Even > though I haven't looked the patch closer, the "SELECT > pg_relation_size()" doesn't seem to give something meaningful > anyway. Maybe then "explain (analyze, buffers, costs off, timing off, summary off) select * from vactst" then. The point is to check that the relation's heap has 0 pages.
