Our database is in use, in reading and writing, 24 hours per day through batch elaborations and online transactional operations. In our scenario, the auto vacuum is dangerous because it can slow down operations in the wrong moment of the day causing low answer times or even unavailability of our web application.
For this reason, we decided to turn off the auto vacuum and manage manually the maintenance routine of our tables: we use pgagent to schedule daily vacuum analyze of our tables and manually run vacuum full on large tables when needed (eg. their size on disk is too large compared to the real data).
One of the main performance bottlenecks is the vacuum of the pg_catalog schema: if we don't perform it regularly it slows down PostgreSQL to a point where our web services start to time out while reading from it.
We would like to tune the autovacuum configuration or, if not possible otherwise, either switching it on or of globally.