Hans-Juergen Schoenig <postgres@cybertec.at> writes:
> overhead is not an issue here - if i lose 10 or 15% i am totally fine as
> long as i can reduce vacuum overhead to an absolute minimum.
I cannot see the sanity of taking a ~10% hit on all I/O activity
(especially foreground queries) to avoid having background vacuuming
going on --- at least assuming that we can keep the impact of vacuuming
below 10%, which I should hope that we could. What your problem sounds
like to me is that you need a smarter autovacuum scheduler. Some of the
map-fork ideas we've discussed would also help, by allowing vacuum to
skip pages that're known to contain only frozen tuples --- your large
low-turnover tables would probably have a lot of those.
regards, tom lane
