Re: vacuum bug

> 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