Re: Draft back-branch release notes are up for review

On Sat, Jun 15, 2019 at 2:11 PM Peter Geoghegan <pg@bowt.ie> wrote:
> On Sat, Jun 15, 2019 at 1:39 PM Noah Misch <noah@leadboat.com> wrote:
> > To me, this text implies a cautious DBA should amcheck every index.  Reading
> > the thread[1], I no longer think that.  It's enough to monitor that VACUUM
> > doesn't start failing persistently on any index.  I suggest replacing this
> > release note text with something like the following:

FWIW, amcheck won't help here. It can only access pages through its
breadth-first search, and so will not land on any "leaked" page (i.e.
page that has no link to the tree). Ideally, amcheck would notice that
it hasn't visited certain blocks, and then inspect the blocks/pages in
a separate pass, but that doesn't happen right now.

As you know, VACUUM can find leaked blocks/pages because nbtree VACUUM
has an optimization that allows it to access them in sequential order.

-- 
Peter Geoghegan