Mastering PostgreSQL 9.6

Configuring VACUUM and autovacuum

Back in the early days of PostgreSQL projects, people had to run VACUUM manually. Fortunately this is long gone. Nowadays administrators can rely on a tool called autovacuum, which is part of the PostgreSQL Server infrastructure. It automatically takes care of cleanup and works in the background. It wakes up once per minute (see autovacuum_naptime = 1 in postgresql.conf) and checks if there is work to do. If there is work, autovacuum will fork up to three worker processes (see autovacuum_max_workers in postgresql.conf).

The main question is: When does autovacuum trigger the creation of a worker process?

Actually the autovacuum process does not fork processes itself. Instead it tells the main process to do ...