Autovacuum is enabled by default in PostgreSQL 9.4, and mostly does a great job of maintaining your PostgreSQL database. We say "mostly" because it doesn't know everything you do about the database, such as the best time to perform maintenance actions.
Exercising control requires some thinking about what you actually want:
The first thing to do is to make sure that autovacuum is switched on. You must have both of the following parameters enabled in your
autovacuum = on ...