Re: ERROR: found multixact XX from before relminmxid YY

Mark Fletcher <markf(at)corp(dot)groups(dot)io> writes:
> Starting yesterday morning, auto vacuuming of one of our postgresql 9.6.10
> (CentOS 7) table's started failing:
> ERROR: found multixact 370350365 from before relminmxid 765860874
> CONTEXT: automatic vacuum of table "userdb.public.subs"

Ugh.

> Reading the various discussions about this error, the only solution I found
> was here:
> https://www.postgresql.org/message-id/CAGewt-ukbL6WL8cc-G%2BiN9AVvmMQkhA9i2TKP4-6wJr6YOQkzA%40mail.gmail.com
> But no other reports of this solving the problem. Can someone verify that
> if I do the mentioned fix (and I assume upgrade to 9.6.11) that will fix
> the problem? And that it doesn't indicate table corruption?

Yeah, SELECT FOR UPDATE should overwrite the broken xmax value and thereby
fix it, I expect. However, I don't see anything in the release notes
suggesting that we've fixed any related bugs since 9.6.10, so if this
just appeared then we've still got a problem :-(. Did anything
interesting happen since your last successful autovacuum on that table?
Database crashes, WAL-related parameter changes, that sort of thing?

regards, tom lane