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

On 2010-05-18 18:57, Bruce Momjian wrote:
> jesper@krogh.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/

Jesper
-- 
Jesper