> There would be *zero* activity on a table undergoing vacuum full, unless
> your app has found a way around vacuum full's exclusive lock. You sure
> this wasn't a plain vacuum?
Hmm...correct. So I don't know what happened.
> > Then vacuum full failed after a while:
> > ERROR: simple_heap_update: tuple concurrently updated
>
> Were you doing VACUUM ANALYZEs?
The background vacuum was doing analyze, the full one was not.
> It's possible for two concurrent VACUUM ANALYZEs of the same table
> to get this failure from trying to concurrently update the same row in
> pg_statistic. (The cure for this seems worse than the disease: AFAICS
> you'd have to prevent *all* concurrent updates of pg_statistic by
> grabbing a table-level lock. So we just live with one of the analyzes
> reporting a failure. All the useful work gets done anyway, by one
> transaction or the other.)
Hmmm...I don't see why I would have had two concurrent analyzes going on...
I guess there's not enough info to diagnose it anyway...
Chris
