Autovacuum is enabled by default in PostgreSQL, 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:
- What are the best times of day to do things? When are system resources more available?
- Which days are quiet, and which are not?
- Which tables are critical to the application, and which are not?