"Ed L." <pgsql@bluepolka.net> writes:
> If I see VACUUM ANALYZE VERBOSE output like this...
> INFO: --Relation public.foo--
> INFO: Index idx_foo_bar: Pages 219213; Tuples 28007: Deleted 9434.
> CPU 17.05s/4.58u sec elapsed 3227.62 sec.
> ...am I correct in reading this to say that it took more than 53 minutes
> (3227 secs) to get 17 seconds of CPU time? Is this an indicator of
> possible I/O contention?
More like "your disk drives are being pounded into the ground" ?
It's hard to evaluate this without knowing what else is going on in your
system at the same time. In general a pure VACUUM process *ought* to be
I/O bound. But without any additional data it's hard to say if 200:1
CPU vs I/O ratio is reasonable or not. Were other things happening at
the same time, and if so did they seem bogged down? What sort of
hardware is this on anyway?
regards, tom lane