log_min_messages per backend type

Change log_min_messages from a single element to a comma-separated list
of elements. Each element is backendtype:loglevel. The backendtype are
archiver, autovacuum (includes launcher and workers), backend, bgworker,
bgwriter, checkpointer, logger, slotsyncworker, walreceiver, walsender,
walsummarizer and walwriter. It should be part of this list a single log
level that is applied as a final step to the backend types that are not
informed.

The old syntax (a single log level) is still accepted for backward
compatibility. In this case, it means the informed log level is applied
for the backend types that are not informed. The default log level is
the same (WARNING) for all backend types.

Author: eulerto

doc/src/sgml/config.sgml

@@ -6999,7 +6999,7 @@ local0.*    /var/log/postgresql
      <variablelist>
 
      <varlistentry id="guc-log-min-messages" xreflabel="log_min_messages">
-      <term><varname>log_min_messages</varname> (<type>enum</type>)
+      <term><varname>log_min_messages</varname> (<type>string</type>)
       <indexterm>
        <primary><varname>log_min_messages</varname> configuration parameter</primary>
       </indexterm>
@@ -7008,14 +7008,26 @@ local0.*    /var/log/postgresql
        <para>
         Controls which <link linkend="runtime-config-severity-levels">message
         levels</link> are written to the server log.
-        Valid values are <literal>DEBUG5</literal>, <literal>DEBUG4</literal>,
-        <literal>DEBUG3</literal>, <literal>DEBUG2</literal>, <literal>DEBUG1</literal>,
-        <literal>INFO</literal>, <literal>NOTICE</literal>, <literal>WARNING</literal>,
-        <literal>ERROR</literal>, <literal>LOG</literal>, <literal>FATAL</literal>, and
-        <literal>PANIC</literal>.  Each level includes all the levels that
-        follow it.  The later the level, the fewer messages are sent
-        to the log.  The default is <literal>WARNING</literal>.  Note that
-        <literal>LOG</literal> has a different rank here than in
+        Valid values are a comma-separated list of <literal>backendtype:level</literal>
+        and a single <literal>level</literal>. The list allows it to use
+        different levels per backend type.
+        Valid <literal>backendtype</literal> values are <literal>archiver</literal>,
+        <literal>autovacuum</literal>, <literal>backend</literal>,
+        <literal>bgworker</literal>, <literal>bgwriter</literal>,
+        <literal>checkpointer</literal>, <literal>logger</literal>,
+        <literal>slotsyncworker</literal>, <literal>walreceiver</literal>,
+        <literal>walsender</literal>, <literal>walsummarizer</literal>, and
+        <literal>walwriter</literal>.
+        Valid <literal>LEVEL</literal> values are <literal>DEBUG5</literal>,
+        <literal>DEBUG4</literal>, <literal>DEBUG3</literal>, <literal>DEBUG2</literal>,
+        <literal>DEBUG1</literal>, <literal>INFO</literal>, <literal>NOTICE</literal>,
+        <literal>WARNING</literal>, <literal>ERROR</literal>, <literal>LOG</literal>,
+        <literal>FATAL</literal>, and <literal>PANIC</literal>.  Each level includes
+        all the levels that follow it.  The later the level, the fewer messages are sent
+        to the log. The single <literal>LEVEL</literal> is mandatory and it is
+        assigned to the backend types that are not specified in the list.  The
+        default is <literal>WARNING</literal> for all backend types.
+        Note that <literal>LOG</literal> has a different rank here than in
         <xref linkend="guc-client-min-messages"/>.
         Only superusers and users with the appropriate <literal>SET</literal>
         privilege can change this setting.

src/backend/commands/extension.c

@@ -1145,7 +1145,7 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		(void) set_config_option("client_min_messages", "warning",
 								 PGC_USERSET, PGC_S_SESSION,
 								 GUC_ACTION_SAVE, true, 0, false);
-	if (log_min_messages < WARNING)
+	if (log_min_messages[MyBackendType] < WARNING)
 		(void) set_config_option_ext("log_min_messages", "warning",
 									 PGC_SUSET, PGC_S_SESSION,
 									 BOOTSTRAP_SUPERUSERID,

src/backend/commands/variable.c

@@ -35,6 +35,7 @@
 #include "utils/datetime.h"
 #include "utils/fmgrprotos.h"
 #include "utils/guc_hooks.h"
+#include "utils/guc_tables.h"
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
 #include "utils/timestamp.h"
@@ -1257,3 +1258,189 @@ check_ssl(bool *newval, void **extra, GucSource source)
 #endif
 	return true;
 }
+
+/*
+ * GUC check_hook for log_min_messages
+ *
+ * The parsing consists of a comma-separated list of BACKENDTYPENAME:LEVEL
+ * elements. BACKENDTYPENAME is log_min_messages_backend_types.  LEVEL is
+ * server_message_level_options. A single LEVEL element should be part of this
+ * list and it is applied as a final step to the backend types that are not
+ * specified. For backward compatibility, the old syntax is still accepted and
+ * it means to apply this level for all backend types.
+ */
+bool
+check_log_min_messages(char **newval, void **extra, GucSource source)
+{
+	char	   *rawstring;
+	List	   *elemlist;
+	ListCell   *l;
+	int			newlevels[BACKEND_NUM_TYPES];
+	bool		assigned[BACKEND_NUM_TYPES];
+	int			genericlevel = -1;	/* -1 means not assigned */
+
+	/* Initialize the array. */
+	memset(newlevels, WARNING, BACKEND_NUM_TYPES * sizeof(int));
+	memset(assigned, false, BACKEND_NUM_TYPES * sizeof(bool));
+
+	/* Need a modifiable copy of string. */
+	rawstring = pstrdup(*newval);
+
+	/* Parse string into list of identifiers. */
+	if (!SplitGUCList(rawstring, ',', &elemlist))
+	{
+		/* syntax error in list */
+		GUC_check_errdetail("List syntax is invalid.");
+		pfree(rawstring);
+		list_free(elemlist);
+		return false;
+	}
+
+	/* Validate and assign log level and backend type. */
+	foreach(l, elemlist)
+	{
+		char	   *tok = (char *) lfirst(l);
+		char	   *sep;
+		const struct config_enum_entry *entry;
+
+		/*
+		 * Check whether there is a backend type following the log level. If
+		 * there is no separator, it means this log level should be applied
+		 * for all backend types (backward compatibility).
+		 */
+		sep = strchr(tok, ':');
+		if (sep == NULL)
+		{
+			bool		found = false;
+
+			/* Reject duplicates for generic log level. */
+			if (genericlevel != -1)
+			{
+				GUC_check_errdetail("Generic log level was already assigned.");
+				pfree(rawstring);
+				list_free(elemlist);
+				return false;
+			}
+
+			/* Is the log level valid? */
+			for (entry = server_message_level_options; entry && entry->name; entry++)
+			{
+				if (pg_strcasecmp(entry->name, tok) == 0)
+				{
+					genericlevel = entry->val;
+					found = true;
+					break;
+				}
+			}
+
+			if (!found)
+			{
+				GUC_check_errdetail("Unrecognized log level: \"%s\".", tok);
+				pfree(rawstring);
+				list_free(elemlist);
+				return false;
+			}
+		}
+		else
+		{
+			char	   *loglevel;
+			char	   *btype;
+			bool		found = false;
+
+			btype = palloc((sep - tok) + 1);
+			memcpy(btype, tok, sep - tok);
+			btype[sep - tok] = '\0';
+			loglevel = pstrdup(sep + 1);
+
+			/* Is the log level valid? */
+			for (entry = server_message_level_options; entry && entry->name; entry++)
+			{
+				if (pg_strcasecmp(entry->name, loglevel) == 0)
+				{
+					found = true;
+					break;
+				}
+			}
+
+			if (!found)
+			{
+				GUC_check_errdetail("Unrecognized log level: \"%s\".", loglevel);
+				pfree(rawstring);
+				list_free(elemlist);
+				return false;
+			}
+
+			/*
+			 * Is the backend type name valid? There might be multiple entries
+			 * per backend type, don't bail out when find first occurrence.
+			 */
+			found = false;
+			for (int i = 0; i < BACKEND_NUM_TYPES; i++)
+			{
+				if (pg_strcasecmp(log_min_messages_backend_types[i], btype) == 0)
+				{
+					newlevels[i] = entry->val;
+					assigned[i] = true;
+					found = true;
+				}
+			}
+
+			if (!found)
+			{
+				GUC_check_errdetail("Unrecognized backend type: \"%s\".", btype);
+				pfree(rawstring);
+				list_free(elemlist);
+				return false;
+			}
+		}
+	}
+
+	/*
+	 * Generic log level must be specified. It is a good idea to specify a
+	 * generic log level to make it clear that it is the fallback value.
+	 * Although, we can document it, it might confuse users that used to
+	 * specify a single log level in prior releases.
+	 */
+	if (genericlevel == -1)
+	{
+		GUC_check_errdetail("Generic log level was not defined.");
+		pfree(rawstring);
+		list_free(elemlist);
+		return false;
+	}
+
+	/*
+	 * Apply the generic log level (the one without a backend type) after all
+	 * of the specific backend type have been assigned. Hence, it doesn't
+	 * matter the order you specify the generic log level, the final result
+	 * will be the same.
+	 */
+	for (int i = 0; i < BACKEND_NUM_TYPES; i++)
+	{
+		if (!assigned[i])
+			newlevels[i] = genericlevel;
+	}
+
+	pfree(rawstring);
+	list_free(elemlist);
+
+	/*
+	 * Pass back data for assign_log_min_messages to use.
+	 */
+	*extra = guc_malloc(LOG, BACKEND_NUM_TYPES * sizeof(int));
+	if (!*extra)
+		return false;
+	memcpy(*extra, newlevels, BACKEND_NUM_TYPES * sizeof(int));
+
+	return true;
+}
+
+/*
+ * GUC assign_hook for log_min_messages
+ */
+void
+assign_log_min_messages(const char *newval, void *extra)
+{
+	for (int i = 0; i < BACKEND_NUM_TYPES; i++)
+		log_min_messages[i] = ((int *) extra)[i];
+}

src/backend/utils/error/elog.c

@@ -235,7 +235,7 @@ is_log_level_output(int elevel, int log_min_level)
 static inline bool
 should_output_to_server(int elevel)
 {
-	return is_log_level_output(elevel, log_min_messages);
+	return is_log_level_output(elevel, log_min_messages[MyBackendType]);
 }
 
 /*

src/backend/utils/misc/guc_tables.c

@@ -146,7 +146,7 @@ static const struct config_enum_entry client_message_level_options[] = {
 	{NULL, 0, false}
 };
 
-static const struct config_enum_entry server_message_level_options[] = {
+const struct config_enum_entry server_message_level_options[] = {
 	{"debug5", DEBUG5, false},
 	{"debug4", DEBUG4, false},
 	{"debug3", DEBUG3, false},
@@ -536,7 +536,6 @@ static bool default_with_oids = false;
 bool		current_role_is_superuser;
 
 int			log_min_error_statement = ERROR;
-int			log_min_messages = WARNING;
 int			client_min_messages = NOTICE;
 int			log_min_duration_sample = -1;
 int			log_min_duration_statement = -1;
@@ -594,6 +593,7 @@ static char *server_version_string;
 static int	server_version_num;
 static char *debug_io_direct_string;
 static char *restrict_nonsystem_relation_kind_string;
+static char *log_min_messages_string;
 
 #ifdef HAVE_SYSLOG
 #define	DEFAULT_SYSLOG_FACILITY LOG_LOCAL0
@@ -638,6 +638,60 @@ char	   *role_string;
 /* should be static, but guc.c needs to get at this */
 bool		in_hot_standby_guc;
 
+/*
+ * This must match enum BackendType! It should be static, but
+ * commands/variable.c needs to get at this.
+ */
+int			log_min_messages[] = {
+	[B_INVALID] = WARNING,
+	[B_BACKEND] = WARNING,
+	[B_DEAD_END_BACKEND] = WARNING,
+	[B_AUTOVAC_LAUNCHER] = WARNING,
+	[B_AUTOVAC_WORKER] = WARNING,
+	[B_BG_WORKER] = WARNING,
+	[B_WAL_SENDER] = WARNING,
+	[B_SLOTSYNC_WORKER] = WARNING,
+	[B_STANDALONE_BACKEND] = WARNING,
+	[B_ARCHIVER] = WARNING,
+	[B_BG_WRITER] = WARNING,
+	[B_CHECKPOINTER] = WARNING,
+	[B_STARTUP] = WARNING,
+	[B_WAL_RECEIVER] = WARNING,
+	[B_WAL_SUMMARIZER] = WARNING,
+	[B_WAL_WRITER] = WARNING,
+	[B_LOGGER] = WARNING,
+};
+
+StaticAssertDecl(lengthof(log_min_messages) == BACKEND_NUM_TYPES,
+				 "array length mismatch");
+
+/*
+ * This must match enum BackendType! It might be in commands/variable.c but for
+ * convenience it is near log_min_messages.
+ */
+const char *const log_min_messages_backend_types[] = {
+	[B_INVALID] = "backend",	/* XXX same as backend? */
+	[B_BACKEND] = "backend",
+	[B_DEAD_END_BACKEND] = "backend",	/* XXX same as backend? */
+	[B_AUTOVAC_LAUNCHER] = "autovacuum",
+	[B_AUTOVAC_WORKER] = "autovacuum",
+	[B_BG_WORKER] = "bgworker",
+	[B_WAL_SENDER] = "walsender",
+	[B_SLOTSYNC_WORKER] = "slotsyncworker",
+	[B_STANDALONE_BACKEND] = "backend", /* XXX same as backend? */
+	[B_ARCHIVER] = "archiver",
+	[B_BG_WRITER] = "bgwriter",
+	[B_CHECKPOINTER] = "checkpointer",
+	[B_STARTUP] = "backend",	/* XXX same as backend? */
+	[B_WAL_RECEIVER] = "walreceiver",
+	[B_WAL_SUMMARIZER] = "walsummarizer",
+	[B_WAL_WRITER] = "walwriter",
+	[B_LOGGER] = "logger",
+};
+
+StaticAssertDecl(lengthof(log_min_messages_backend_types) == BACKEND_NUM_TYPES,
+				 "array length mismatch");
+
 
 /*
  * Displayable names for context types (enum GucContext)
@@ -4298,6 +4352,18 @@ struct config_string ConfigureNamesString[] =
 		check_client_encoding, assign_client_encoding, NULL
 	},
 
+	{
+		{"log_min_messages", PGC_SUSET, LOGGING_WHEN,
+			gettext_noop("Sets the message levels that are logged."),
+			gettext_noop("Each level includes all the levels that follow it. The later"
+						 " the level, the fewer messages are sent."),
+			GUC_LIST_INPUT
+		},
+		&log_min_messages_string,
+		"WARNING",
+		check_log_min_messages, assign_log_min_messages, NULL
+	},
+
 	{
 		{"log_line_prefix", PGC_SIGHUP, LOGGING_WHAT,
 			gettext_noop("Controls information prefixed to each log line."),
@@ -5110,17 +5176,6 @@ struct config_enum ConfigureNamesEnum[] =
 		NULL, NULL, NULL
 	},
 
-	{
-		{"log_min_messages", PGC_SUSET, LOGGING_WHEN,
-			gettext_noop("Sets the message levels that are logged."),
-			gettext_noop("Each level includes all the levels that follow it. The later"
-						 " the level, the fewer messages are sent.")
-		},
-		&log_min_messages,
-		WARNING, server_message_level_options,
-		NULL, NULL, NULL
-	},
-
 	{
 		{"log_min_error_statement", PGC_SUSET, LOGGING_WHEN,
 			gettext_noop("Causes all statements generating error at or above this level to be logged."),

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

@@ -543,6 +543,7 @@
 					#   log
 					#   fatal
 					#   panic
+					#   or a comma-separated list of backend_type:level
 
 #log_min_error_statement = error	# values in order of decreasing detail:
 					#   debug5

src/include/miscadmin.h

@@ -333,6 +333,8 @@ extern void SwitchBackToLocalLatch(void);
  *
  * If you add entries, please also update the child_process_kinds array in
  * launch_backend.c.
+ * XXX If you add a new backend type or change the order, update
+ * log_min_messages because it relies on this order to work correctly.
  */
 typedef enum BackendType
 {