Re: pg_upgrade - link mode and transaction-wraparound data loss

Jesper Krogh wrote:
> On 2010-05-18 18:57, Bruce Momjian wrote:
> > jesper(at)krogh(dot)cc wrote:
> >
> >> Hi
> >>
> >> I tried running pg_upgrade from the current snapshot of postgresql and
> >> upgrading from 8.4.4 to the snapshot version. Everything seem to look fine
> >> in the process and all that came out was only "ok's" but when I tried a
> >> simple query on the databse it keeps throwing these message out of the back
> >> side.
> >>
> >> DETAIL: You might have already suffered transaction-wraparound data loss.
> >> WARNING: some databases have not been vacuumed in over 2 billion
> >> transactions
> >>
> >>
> >> The database was around 600GB and it took a couple of minutes to run
> >> pg_upgrade after I had all the binaries in the correct place.
> >>
> >> It is not really an easy task to throw around 600GB of data, so I cannot
> >> gaurantee that the above is reproducible, but I'll see if I can get time
> >> and try to reproduce it.
> >>
> > This certainly should never have happened, so I am guessing it is a bug.
> > pg_upgrade tries hard to make sure all your datfrozenxid and
> > relfrozenxid are properly migrated from the old server, and the
> > transaction id is set properly. Unfortunately this is the first time I
> > have heard of such a problem, so I am unclear on its cause.
> >
>
> Other people are typically way faster than I am looking into it.
> Depesz has produced a full trace to reproduce the problem here:
> http://www.depesz.com/index.php/2010/05/19/waiting-for-9-0-pg_upgrade/

Thanks. I have commented on the blog to mention that we have fixed the
bug reported there.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com