[postgres@localhost data]$ grep autova postgresql.conf
#autovacuum_work_mem = -1 # min 1MB, or -1 to use maintenance_work_mem
#log_autovacuum_min_duration = 10min # log autovacuum activity;
#autovacuum = on # Enable autovacuum subprocess? 'on'
#autovacuum_max_workers = 3 # max number of autovacuum subprocesses
#autovacuum_naptime = 1min # time between autovacuum runs
#autovacuum_vacuum_threshold = 50 # min number of row updates before
#autovacuum_vacuum_insert_threshold = 1000 # min number of row inserts
#autovacuum_analyze_threshold = 50 # min number of row updates before
#autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum
#autovacuum_vacuum_insert_scale_factor = 0.2 # fraction of inserts over table
#autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum
#autovacuum_multixact_freeze_max_age = 400000000 # maximum multixact age
#autovacuum_vacuum_cost_delay = 2ms # default vacuum cost delay for
# autovacuum, in milliseconds;
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
# autovacuum, -1 means use

从配置文件看，默认是禁用了。