Joe Miller <joe(dot)d(dot)miller(at)gmail(dot)com> writes:
> The autovacuum daemon currently uses the number of inserted and
> updated tuples to determine if it should run VACUUM ANALYZE on a
> table. Why doesnt it consider deleted tuples as well?
I think you misread the code.
Now there *is* a problem, pre-9.0, if your update pattern is such that
most or all updates are HOT updates. To quote from the 9.0 alpha
Revise pgstat's tracking of tuple changes to
improve the reliability of decisions about when to
auto-analyze. The previous code depended on n_live_tuples +
n_dead_tuples - last_anl_tuples, where all three of these
numbers could be bad estimates from ANALYZE itself. Even
worse, in the presence of a steady flow of HOT updates and
matching HOT-tuple reclamations, auto-analyze might never
trigger at all, even if all three numbers are exactly right,
because n_dead_tuples could hold steady.
It's not clear to me if that matches your problem, though.
regards, tom lane
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