autovacuum_max_workers is a configuration parameter specifying the maximum number of autovacuum processes which can run simultaneously.
autovacuum_max_workers was added in PostgreSQL 8.3.
autovacuum_max_workers controlls the actual number of autovacuum processes which can be launched as the same time. The autovacuum launcher itself is not included in this number.
autovacuum_max_workers is a global cluster setting, not per-database. This means that depending on the
autovacuum_max_workers setting and the number of databases present, autovacuum may not run on all databases simultaenously.
The default value for