On 2016-06-06 16:18:19 -0400, Stephen Frost wrote:
> That could be as simple as a query with the right things installed, or
> it might be an independent tool, but not having any way to check isn't
> good. That said, trying to make VACUUM do that doesn't make sense to me
> either.
The point is that VACUUM *has* these types of checks. And had so for
many years: else if (all_visible_according_to_vm && !PageIsAllVisible(page) && VM_ALL_VISIBLE(onerel,
blkno,&vmbuffer)) { elog(WARNING, "page is not marked all-visible but visibility map bit is set in relation
\"%s\"page %u", relname, blkno); visibilitymap_clear(onerel, blkno, vmbuffer); }
... else if (PageIsAllVisible(page) && has_dead_tuples) { elog(WARNING, "page containing dead tuples is
markedas all-visible in relation \"%s\" page %u", relname, blkno); PageClearAllVisible(page);
MarkBufferDirty(buf); visibilitymap_clear(onerel, blkno, vmbuffer); }
the point is that, after the introduction of the freeze bit, there's no
way to reach them anymore (and they're missing a useful extension of
these warnings, but ...); these warnings have caught bugs. I don't
think it'd advocate for the vacuum option otherwise.
Greetings,
Andres Freund