diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 13408899dc..83e7c254dc 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -362,6 +362,8 @@
 #---------------------------------------------------------------------------
 
 #autovacuum = off			# enable autovacuum subprocess?
+					# 'on' requires stats_start_collector
+					# and stats_row_level to also be on
 #autovacuum_naptime = 1min		# time between autovacuum runs
 #autovacuum_vacuum_threshold = 500	# min # of tuple updates before
 					# vacuum