On 2018-02-26 20:09:31 -0300, Alvaro Herrera wrote: > Alexandre Garcia wrote: > > > Recently our team performed an upgrade on one of our old postgres 9.2 > > databases. "for science" we tried a direct upgrade from 9.2 to 9.6 on our > > staging environment . The initial plan was to do 9.2 -> 9.4 and 9.4 -> 9.6. > > > > The upgrade turned out successful on staging and we decided to go with it > > on prod as well. > > Prod starting throwing the following errors during autovacuum -> 'cannot > > freeze committed xmax <xid>' on 2 different tables. Running vacuum manually > > revealed more tables affected by the same error. > > > > The staging database did not present any error but the process to sync prod > > to stage includes a sanitize script that removes sensitive information and > > it somehow seems to fix the issue on stage (we've done a sync from prod to > > stage after the upgrade) > > > > I've been doing a lot of search about this and even tried to go through the > > code that throws that specific error. Could you show pg_controldata from before/after pg_upgrade, and the output of SELECT oid::regclass, relfrozenxid, age(relfrozenxid), txid_current() FROM pg_class WHERE oid = 'problematic_table'::regclass; from both before/after? > This particular error condition is a sanity check that was only > introduced in 9.6.7, so you would not find too many reports of that > (this exact error message wording doesn't exist prior to that). It is > possible that we missed some corner case when writing that check. > Upgrades from 9.2 are particularly unusual since the xmax header was > reused in the 9.3 era to mean something completely different under some > circumstances. I'm not in a position to do deeper debugging for you at > this time, though. > > The commit in question is > https://git.postgresql.org/pg/commitdiff/986a9153b9708071adf6ce2c9131266f3431f4ec > > Wild guess: maybe we should be checking HEAP_LOCKED_UPGRADED before > bailing out. Doesn't !(tuple->t_infomask & HEAP_XMAX_LOCK_ONLY) already guard against that? Greetings, Andres Freund
