Arnau wrote:
> I'm migrating our DDBB from postgresql 7.4 to postgresql 8.1. In
> postgreql 7.4 we don't have autovaccum running. So, every night before
> doing the daily backup we do a "vaccuumdb -f -z" for each DB. My doubt
> is, the autovaccuum with the version 8.1 is started by default and I
> don't know how often I should perform the "vaccuumdb -f -z" or now
> it's not necessary to do it at all.
First off, you should never really need vacuumdb -f, in fact autovacuum
doesn't do full vacuums, rather it only does the standard vacuum.
In theory autovacuum should perform all the vacuuming that is needed,
however, in practice this isn't always the case. First the most people
find the default thresholds for autovacuum in 8.1 are too conservative
and second it can be a bit hard to monitor what autovacuum is doing.
Both of these issues are improved in 8.2. In summary, try it and see.