Handle synchronous_standby_names defaults better

Author: Michael Conrad

defaults/main.yml

@@ -290,7 +290,7 @@ postgresql_track_commit_timestamp: off # (>= 9.5)
 
 # standby servers that provide sync rep.
 # number of sync standbys (>= 9.6) and comma-separated list of application_name from standby(s)
-postgresql_synchronous_standby_num_sync: 1
+postgresql_synchronous_standby_num_sync: ''
 postgresql_synchronous_standby_names: [] # '*' means 'all'
 
 # number of xacts by which cleanup is delayed

templates/postgresql.conf-9.6.j2

@@ -244,7 +244,7 @@ track_commit_timestamp = {{'on' if postgresql_track_commit_timestamp else 'off'
 
 # These settings are ignored on a standby server.
 
-synchronous_standby_names = '{{postgresql_synchronous_standby_num_sync}} ({{postgresql_synchronous_standby_names|join(',')}})'	# standby servers that provide sync rep
+synchronous_standby_names = '{{postgresql_synchronous_standby_num_sync}}{% if postgresql_synchronous_standby_names != [] %} ({{postgresql_synchronous_standby_names|join(',')}}){% endif %}'	# standby servers that provide sync rep
 				# number of sync standbys and comma-separated list of application_name
 				# from standby(s); '*' = all
 vacuum_defer_cleanup_age = {{postgresql_vacuum_defer_cleanup_age}}	# number of xacts by which cleanup is delayed