diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index f43086f..5044450 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -154,6 +154,11 @@
 #vacuum_cost_page_dirty = 20		# 0-10000 credits
 #vacuum_cost_limit = 200		# 1-10000 credits
 
+# - Index Vacuum -
+#vacuum_cleanup_index_scale_factor = 0.1	# fraction of total number of tuples
+						# before index cleanup. 0 never skips
+						# cleanup index
+
 # - Background Writer -
 
 #bgwriter_delay = 200ms			# 10-10000ms between rounds