Change default values for backup and replication parameters

This changes the default values of the following parameters:

wal_level = replica
max_wal_senders = 10
max_replication_slots = 10

in order to make it possible to make a backup and set up simple
replication on the default settings, without requiring a system restart.

Discussion: https://postgr.es/m/CABUevEy4PR_EAvZEzsbF5s+V0eEvw7shJ2t-AUwbHOjT+yRb3A@mail.gmail.com

Reviewed by Peter Eisentraut. Benchmark help from Tomas Vondra.

7 files changed, 11 insertions, 11 deletions

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 5b23dbf4a0e..4e2bd4c496a 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2315,7 +2315,7 @@ static struct config_int ConfigureNamesInt[] =
 			NULL
 		},
 		&max_wal_senders,
-		0, 0, MAX_BACKENDS,
+		10, 0, MAX_BACKENDS,
 		NULL, NULL, NULL
 	},
 
@@ -2326,7 +2326,7 @@ static struct config_int ConfigureNamesInt[] =
 			NULL
 		},
 		&max_replication_slots,
-		0, 0, MAX_BACKENDS /* XXX? */ ,
+		10, 0, MAX_BACKENDS /* XXX? */ ,
 		NULL, NULL, NULL
 	},
 
@@ -3749,7 +3749,7 @@ static struct config_enum ConfigureNamesEnum[] =
 			NULL
 		},
 		&wal_level,
-		WAL_LEVEL_MINIMAL, wal_level_options,
+		WAL_LEVEL_REPLICA, wal_level_options,
 		NULL, NULL, NULL
 	},
 
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index b3f29610d07..15669b83c7f 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -174,7 +174,7 @@
 
 # - Settings -
 
-#wal_level = minimal			# minimal, replica, or logical
+#wal_level = replica			# minimal, replica, or logical
 					# (change requires restart)
 #fsync = on				# flush data to disk for crash safety
 					# (turning this off can cause
@@ -229,12 +229,12 @@
 
 # Set these on the master and on any standby that will send replication data.
 
-#max_wal_senders = 0		# max number of walsender processes
+#max_wal_senders = 10		# max number of walsender processes
 				# (change requires restart)
 #wal_keep_segments = 0		# in logfile segments, 16MB each; 0 disables
 #wal_sender_timeout = 60s	# in milliseconds; 0 disables
 
-#max_replication_slots = 0	# max number of replication slots
+#max_replication_slots = 10	# max number of replication slots
 				# (change requires restart)
 #track_commit_timestamp = off	# collect timestamp of transaction commit
 				# (change requires restart)
diff --git a/src/test/modules/commit_ts/t/002_standby.pl b/src/test/modules/commit_ts/t/002_standby.pl
index 4dbde2978e4..ff600445406 100644
--- a/src/test/modules/commit_ts/t/002_standby.pl
+++ b/src/test/modules/commit_ts/t/002_standby.pl
@@ -15,7 +15,6 @@ $master->append_conf(
 	'postgresql.conf', qq{
 	track_commit_timestamp = on
 	max_wal_senders = 5
-	wal_level = hot_standby
 	});
 $master->start;
 $master->backup($bkplabel);
diff --git a/src/test/modules/commit_ts/t/003_standby_2.pl b/src/test/modules/commit_ts/t/003_standby_2.pl
index 043ccb14a5d..1775b22dadf 100644
--- a/src/test/modules/commit_ts/t/003_standby_2.pl
+++ b/src/test/modules/commit_ts/t/003_standby_2.pl
@@ -14,7 +14,6 @@ $master->append_conf(
 	'postgresql.conf', qq{
 	track_commit_timestamp = on
 	max_wal_senders = 5
-	wal_level = hot_standby
 	});
 $master->start;
 $master->backup($bkplabel);
diff --git a/src/test/perl/PostgresNode.pm b/src/test/perl/PostgresNode.pm
index d8be1bd3e12..932478183a8 100644
--- a/src/test/perl/PostgresNode.pm
+++ b/src/test/perl/PostgresNode.pm
@@ -415,7 +415,6 @@ sub init
 
 	if ($params{allows_streaming})
 	{
-		print $conf "wal_level = replica\n";
 		print $conf "max_wal_senders = 5\n";
 		print $conf "wal_keep_segments = 20\n";
 		print $conf "max_wal_size = 128MB\n";
@@ -424,6 +423,11 @@ sub init
 		print $conf "hot_standby = on\n";
 		print $conf "max_connections = 10\n";
 	}
+	else
+	{
+		print $conf "wal_level = minimal\n";
+		print $conf "max_wal_senders = 0\n";
+	}
 
 	if ($TestLib::windows_os)
 	{
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index b80a9a9415a..1716360a170 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -10,7 +10,6 @@ my $node_master = get_new_node('master');
 $node_master->init(allows_streaming => 1);
 $node_master->append_conf(
 		'postgresql.conf', qq(
-max_replication_slots = 4
 wal_level = logical
 ));
 $node_master->start;
diff --git a/src/test/recovery/t/008_fsm_truncation.pl b/src/test/recovery/t/008_fsm_truncation.pl
index 9f6bdb0b64b..5220611e445 100644
--- a/src/test/recovery/t/008_fsm_truncation.pl
+++ b/src/test/recovery/t/008_fsm_truncation.pl
@@ -14,7 +14,6 @@ $node_master->init(allows_streaming => 1);
 
 $node_master->append_conf('postgresql.conf', qq{
 fsync = on
-wal_level = replica
 wal_log_hints = on
 max_prepared_transactions = 5
 autovacuum = off