Add syslog_split_messages parameter

Reviewed-by: Andreas Karlsson <andreas@proxel.se>

doc/src/sgml/config.sgml

@@ -4333,6 +4333,39 @@ local0.*    /var/log/postgresql
       </listitem>
      </varlistentry>
 
+     <varlistentry id="guc-syslog-split-messages" xreflabel="syslog_split_messages">
+      <term><varname>syslog_split_messages</varname> (<type>boolean</type>)
+      <indexterm>
+       <primary><varname>syslog_split_messages</> configuration parameter</primary>
+      </indexterm>
+      </term>
+      <listitem>
+       <para>
+        When logging to <application>syslog</> is enabled, this parameter
+        determines how messages are delivered to syslog.  When on (the
+        default), messages are split by lines, and long lines are split so
+        that they will fit into 1024 bytes, which is a typical size limit for
+        traditional syslog implementations.  When off, PostgreSQL server log
+        messages are delivered to the syslog service as is, and it is up to
+        the syslog service to cope with the potentially bulky messages.
+       </para>
+
+       <para>
+        If syslog is ultimately logging to a text file, then the effect will
+        be the same either way, and it is best to leave the setting on, since
+        most syslog implementations either cannot handle large messages or
+        would need to be specially configured to handle them.  But if syslog
+        is ultimately writing into some other medium, it might be necessary or
+        more useful to keep messages logically together.
+       </para>
+
+       <para>
+        This parameter can only be set in the <filename>postgresql.conf</>
+        file or on the server command line.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry id="guc-event-source" xreflabel="event_source">
       <term><varname>event_source</varname> (<type>string</type>)
       <indexterm>

src/backend/utils/error/elog.c

@@ -107,6 +107,7 @@ char	   *Log_line_prefix = NULL;		/* format for extra log line info */
 int			Log_destination = LOG_DESTINATION_STDERR;
 char	   *Log_destination_string = NULL;
 bool		syslog_sequence_numbers = true;
+bool		syslog_split_messages = true;
 
 #ifdef HAVE_SYSLOG
 
@@ -1966,7 +1967,7 @@ write_syslog(int level, const char *line)
 	 */
 	len = strlen(line);
 	nlpos = strchr(line, '\n');
-	if (len > PG_SYSLOG_LIMIT || nlpos != NULL)
+	if (syslog_split_messages && (len > PG_SYSLOG_LIMIT || nlpos != NULL))
 	{
 		int			chunk_nr = 0;
 

src/backend/utils/misc/guc.c

@@ -1642,6 +1642,16 @@ static struct config_bool ConfigureNamesBool[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"syslog_split_messages", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Split messages sent to syslog by lines and to fit into 1024 bytes."),
+			NULL
+		},
+		&syslog_split_messages,
+		true,
+		NULL, NULL, NULL
+	},
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, false, NULL, NULL, NULL

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

@@ -359,6 +359,7 @@
 #syslog_facility = 'LOCAL0'
 #syslog_ident = 'postgres'
 #syslog_sequence_numbers = on
+#syslog_split_messages = on
 
 # This is only relevant when logging to eventlog (win32):
 #event_source = 'PostgreSQL'

src/include/utils/elog.h

@@ -398,6 +398,7 @@ extern char *Log_line_prefix;
 extern int	Log_destination;
 extern char *Log_destination_string;
 extern bool syslog_sequence_numbers;
+extern bool syslog_split_messages;
 
 /* Log destination bitmap */
 #define LOG_DESTINATION_STDERR	 1