Re: pg_upgrade and frozen xids

On Tue, Mar 6, 2018 at 3:41 PM, Natalie Wenz <nataliewenz(at)ebureau(dot)com>
wrote:

> They are not, unfortunately (fortunately?). Just a standard table.
>
> If it helps, the autovacuum always seems to be in the phase "cleaning up
> indexes" when I look at pg_stat_progress_vacuum.
>

​We recently upgraded about 1500 Postgres clusters from 9.3 to 10.1 and we
are seeing similar issues. Specifically:
* An autovacuum worker stuck vacuuming regular tables for days until they
are killed (I've seen "vacuuming indexes" phase), and they are showing 99%
CPU in top. pg_cancel|terminate_backend does not usually kill the process,
only a hard kill does. In the latter case, two (out of four) times it also
crashed Postgres.
* There have been about 10 examples of btree index corruption, across a
handful of databases, in different data centres. In two of the cases, it's
possible there were hardware issues as the hypervisor those two VM's were
running on crashed.