Kevin Barnard <kevin(dot)barnard(at)gmail(dot)com> writes:
> I know I've seen this message before but I'm not quite sure what it
> means. I think it's because I have two vacuums running over each
> other. Does this sound right? It's comming from 7.4.x server.
> ERROR: tuple concurrently updated
Were they both VACUUM ANALYZEs? There's a known gotcha that if you
ANALYZE the same table concurrently in two different sessions, one
of them can fail this way when it goes to update the pg_statistic
entries. (Harmless, but annoying.) I don't know of any cause for
this message from a plain VACUUM though.
regards, tom lane