"Paul B. Anderson" <paul(at)pnlassociates(dot)com> writes:
> My postgresql.conf file had a 10 second timeout and the large database
> required more than 10 seconds for the vacuum. It seems that this left
> postmaster and/or the particular database in a state where any SQL
> against that database gave the same error response about being canceled
> by the user.
Hmm, I couldn't duplicate this. I thought maybe the vacuum wasn't
releasing some lock after it failed, but there's no sign of such a
problem.
Are you sure it isn't just that all your queries were running into the
timeout?
regards, tom lane