Default to log_checkpoints=on, log_autovacuum_min_duration=10m

The idea here is that when a performance problem is known to have
occurred at a certain point in time, it's a good thing if there is
some information available from the logs to help figure out what
might have happened around that time.

This change attracted an above-average amount of dissent, because
it means that a server with default settings will produce some amount
of log output even if nothing has gone wrong. However, by my count,
the mailing list discussion had about twice as many people in favor
of the change as opposed. The reasons for believing that the extra
log output is not an issue in practice are: (1) the rate at which
messages can be generated by this setting is bounded to one every
few minutes on a properly-configured system and (2) production
systems tend to have a lot more junk in the log from that due to
failed connection attempts, ERROR messages generated by application
activity, and the like.

Bharath Rupireddy, reviewed by Fujii Masao and by me. Many other
people commented on the thread, but as far as I can see that was
discussion of the merits of the change rather than review of the
patch.

Discussion: https://postgr.es/m/CALj2ACX-rW_OeDcp4gqrFUAkf1f50Fnh138dmkd0JkvCNQRKGA@mail.gmail.com

doc/src/sgml/config.sgml

@@ -6764,19 +6764,18 @@ local0.*    /var/log/postgresql
        <para>
         Causes each action executed by autovacuum to be logged if it ran for at
         least the specified amount of time.  Setting this to zero logs
-        all autovacuum actions. <literal>-1</literal> (the default) disables
+        all autovacuum actions. <literal>-1</literal> disables logging autovacuum
-        logging autovacuum actions.
+        actions. If this value is specified without units, it is taken as milliseconds.
-        If this value is specified without units, it is taken as milliseconds.
         For example, if you set this to
         <literal>250ms</literal> then all automatic vacuums and analyzes that run
         250ms or longer will be logged.  In addition, when this parameter is
         set to any value other than <literal>-1</literal>, a message will be
         logged if an autovacuum action is skipped due to a conflicting lock or a
-        concurrently dropped relation.  Enabling this parameter can be helpful
+        concurrently dropped relation. The default is <literal>10min</literal>.
-        in tracking autovacuum activity.  This parameter can only be set in
+        Enabling this parameter can be helpful in tracking autovacuum activity.
-        the <filename>postgresql.conf</filename> file or on the server command line;
+        This parameter can only be set in the <filename>postgresql.conf</filename>
-        but the setting can be overridden for individual tables by
+        file or on the server command line; but the setting can be overridden for
-        changing table storage parameters.
+        individual tables by changing table storage parameters.
        </para>
       </listitem>
      </varlistentry>
@@ -6793,7 +6792,7 @@ local0.*    /var/log/postgresql
         Some statistics are included in the log messages, including the number
         of buffers written and the time spent writing them.
         This parameter can only be set in the <filename>postgresql.conf</filename>
-        file or on the server command line. The default is off.
+        file or on the server command line. The default is on.
        </para>
       </listitem>
      </varlistentry>

src/backend/access/transam/xlog.c

@@ -107,7 +107,7 @@ char	   *wal_consistency_checking_string = NULL;
 bool	   *wal_consistency_checking = NULL;
 bool		wal_init_zero = true;
 bool		wal_recycle = true;
-bool		log_checkpoints = false;
+bool		log_checkpoints = true;
 int			sync_method = DEFAULT_SYNC_METHOD;
 int			wal_level = WAL_LEVEL_MINIMAL;
 int			CommitDelay = 0;	/* precommit delay in microseconds */

src/backend/postmaster/autovacuum.c

@@ -127,7 +127,7 @@ int			autovacuum_multixact_freeze_max_age;
 double		autovacuum_vac_cost_delay;
 int			autovacuum_vac_cost_limit;
 
-int			Log_autovacuum_min_duration = -1;
+int			Log_autovacuum_min_duration = 600000;
 
 /* how long to keep pgstat data in the launcher, in milliseconds */
 #define STATS_READ_DELAY 1000

src/backend/utils/misc/guc.c

@@ -1352,7 +1352,7 @@ static struct config_bool ConfigureNamesBool[] =
 			NULL
 		},
 		&log_checkpoints,
-		false,
+		true,
 		NULL, NULL, NULL
 	},
 	{
@@ -3005,7 +3005,7 @@ static struct config_int ConfigureNamesInt[] =
 			GUC_UNIT_MS
 		},
 		&Log_autovacuum_min_duration,
-		-1, -1, INT_MAX,
+		600000, -1, INT_MAX,
 		NULL, NULL, NULL
 	},
 

src/backend/utils/misc/postgresql.conf.sample

@@ -534,12 +534,12 @@
 #debug_print_rewritten = off
 #debug_print_plan = off
 #debug_pretty_print = on
-#log_autovacuum_min_duration = -1	# log autovacuum activity;
+#log_autovacuum_min_duration = 10min	# log autovacuum activity;
 					# -1 disables, 0 logs all actions and
 					# their durations, > 0 logs only
 					# actions running at least this number
 					# of milliseconds.
-#log_checkpoints = off
+#log_checkpoints = on
 #log_connections = off
 #log_disconnections = off
 #log_duration = off

src/bin/initdb/initdb.c

@@ -200,8 +200,8 @@ static bool authwarning = false;
  * but here it is more convenient to pass it as an environment variable
  * (no quoting to worry about).
  */
-static const char *boot_options = "-F";
+static const char *boot_options = "-F -c log_checkpoints=false";
-static const char *backend_options = "--single -F -O -j -c search_path=pg_catalog -c exit_on_error=true";
+static const char *backend_options = "--single -F -O -j -c search_path=pg_catalog -c exit_on_error=true -c log_checkpoints=false";
 
 /* Additional switches to pass to backend (either boot or standalone) */
 static char *extra_options = "";