> The database has around 40 Gb. > If I not use vacuum full everyday the database get very slow. > > There is no deadlock on the database.
You didn't mention if you were using autovacuum or not. You also didn't mention whether or not you'd tried regular vacuums if for some reason you can't use autovacuum. Vacuum full is very intrusive and can cause index bloat. It's more of a repair operation than a routine maintenance one.
What do the last 10 or so lines of vacuum verbose run as a super user say?
