Autovacuum methods automates the executions vacuum,freeze and analyze commands.

-- Find whether autovacuum is enabled or not:

dbaclass=# select name,setting,short_desc,boot_val,pending_restart from pg_settings where name in ('autovacuum','track_counts');
name.         | setting | short_desc                                | boot_val | pending_restart
--------------+---------+-------------------------------------------+----------+-----------------
autovacuum    | on      | Starts the autovacuum subprocess.         | on        | f
track_counts  | on      | Collects statistics on database activity. | on        | f
(2 rows)

-- Find other autovacuum related parameter settings
dbaclass=# select name,setting,short_desc,min_val,max_val,enumvals,boot_val,pending_restart from pg_settings where category like 'Autovacuum';


- Change autovacuum settings:( they need restart)

dbaclass=# alter system set autovacuum_max_workers=10 ;
ALTER SYSTEM

Now restart :

pg_ctl stop
pg_ctl start