On 2022-Nov-23, Peter Geoghegan wrote: > On Wed, Nov 23, 2022 at 2:54 AM Alvaro Herrera <alvhe...@alvh.no-ip.org> > wrote: > > Something like the attached. It would result in output like this: > > WARNING: new multixact has more than one updating member: 0 2[17378 > > (keysh), 17381 (nokeyupd)] > > > > Then it should be possible to trace (in pg_waldump output) the > > operations of each of the transactions that have any status in the > > multixact that includes some form of "upd". > > That seems very useful.
Okay, pushed to all branches. > Separately, I wonder if it would make sense to add additional > defensive checks to FreezeMultiXactId() for this. There is an > assertion that should catch the presence of multiple updaters in a > single Multi when it looks like we have to generate a new Multi to > carry the XID members forward (typically something we only need to do > during a VACUUM FREEZE). We could at least make that > "Assert(!TransactionIdIsValid(update_xid));" line into a defensive > "can't happen" ereport(). It couldn't hurt, at least -- we already > have a similar relfrozenxid check nearby, added after the "freeze the > dead" bug was fixed. Hmm, agreed. I'll see about that separately. -- Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/ "I'm always right, but sometimes I'm more right than other times." (Linus Torvalds)
