"Nicholson, Brad (Toronto, ON, CA)" <bnicholson@hp.com> writes:
> I'm seeing something odd in my DB stats. This is PG 9.2.4 on CentOS. I know the stats collector can be off at
times,but I am curious as to why it would be off in such a case. I know that under heavy load the stats collector can
beoff sometimes, but this system was barely doing anything (CPU ~ 90% idle). PG didn't shutdown at all either.
Most likely there was some DML happening concurrently with a VACUUM or
ANALYZE at some point in the past. VACUUM/ANALYZE update the live and
dead tuple counts based on what they saw, but a transaction that added
such tuples (that were counted by the maintenance op) could commit after
that happens, and then you end up with double-counted tuples.
regards, tom lane