Add:

#log_line_prefix = ''         # e.g. '<%u%%%d> '
                              # %u=user name %d=database name
                              # %r=remote host and port
                              # %p=PID %t=timestamp %i=command tag
                              # %c=session id %l=session line number
                              # %s=session start timestamp
                              # %x=stop here in non-session processes
                              # %%='%'

Andrew Dunstan

doc/src/sgml/runtime.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.245 2004/03/07 01:02:55 neilc Exp $
+$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.246 2004/03/09 04:43:06 momjian Exp $
 -->
 
 <Chapter Id="runtime">
@@ -1972,6 +1972,98 @@ SET ENABLE_SEQSCAN TO OFF;
       </listitem>
      </varlistentry>
      
+     <varlistentry>
+      <term><varname>log_line_prefix</varname> (<type>string</type>)</term>
+      <listitem>
+       <para>
+	 This is a <literal>printf</>-style string that is output at the
+	 beginning of each log line. The default is an empty string.
+	 Each recognized escape is replaced as outlined 
+	 below - anything else that looks like an escape is ignored. Other
+	 characters are copied straight to the log line. Some escapes are
+	 only recognised by session processes, and do not apply to
+	 processes without controlling sessions. <application>Syslog</> produces its own
+	 timestamp and process ID information, so you probably do not want to
+	 use those escapes if you are using <application>syslog</>.
+	 <informaltable>
+	  <tgroup cols="3">
+	   <thead>
+	    <row>
+	     <entry>Escape</entry>
+	     <entry>Effect</entry>
+	     <entry>Session only</entry>
+	     </row>
+	    </thead>
+	   <tbody>
+	    <row>
+	     <entry><literal>%u</literal></entry>
+	     <entry>User Name</entry>
+	     <entry>Yes</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%d</literal></entry>
+	     <entry>Database Name</entry>
+	     <entry>Yes</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%r</literal></entry>
+	     <entry>Remote Hostname or IP address, and Remote Port</entry>
+	     <entry>Yes</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%p</literal></entry>
+	     <entry>Process ID</entry>
+	     <entry>No</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%t</literal></entry>
+	     <entry>Timestamp</entry>
+	     <entry>No</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%i</literal></entry>
+	     <entry>Command Tag. This is the command which generated the log
+	      line.</entry>
+	     <entry>Yes</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%c</literal></entry>
+	     <entry>Session ID. A unique identifier for each session.
+	     It is 2 4-byte hexadecimal numbers separated by a dot. The numbers
+	     are the Session Start Time and the Process ID, so this can also
+	     be used as a space saving way of printing these items.</entry>
+	     <entry>Yes</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%l</literal></entry>
+	     <entry>Number of the log line for each process, 
+	      starting at 1</entry>
+	     <entry>No</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%s</literal></entry>
+	     <entry>Session Start Timestamp</entry>
+	     <entry>Yes</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%x</literal></entry>
+	     <entry>Does not produce any output, but tells non-session
+	     processes to stop at this point in the string. Ignored by
+	     session backends.</entry>
+	     <entry>No</entry>
+	    </row>
+	    <row>
+	     <entry><literal>%%</literal></entry>
+	     <entry>literal <literal>%</></entry>
+	     <entry>No</entry>
+	    </row>
+	   </tbody>
+	  </tgroup>
+	 </informaltable>
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><varname>log_pid</varname> (<type>boolean</type>)</term>
       <listitem>

src/backend/postmaster/postmaster.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.370 2004/03/05 01:11:04 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.371 2004/03/09 04:43:06 momjian Exp $
  *
  * NOTES
  *
@@ -2437,6 +2437,7 @@ BackendInit(Port *port)
 	/* set these to empty in case they are needed before we set them up */
 	port->remote_host = "";
 	port->remote_port = "";
+	port->commandTag = "";
 
 	/* Save port etc. for ps status */
 	MyProcPort = port;
@@ -2489,7 +2490,7 @@ BackendInit(Port *port)
 		/* modify remote_host for use in ps status */
 		char		tmphost[NI_MAXHOST];
 
-		snprintf(tmphost, sizeof(tmphost), "%s:%s", remote_host, remote_port);
+		snprintf(tmphost, sizeof(tmphost), "%s(%s)", remote_host, remote_port);
 		StrNCpy(remote_host, tmphost, sizeof(remote_host));
 	}
 

src/backend/tcop/postgres.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.393 2004/02/21 06:29:58 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.394 2004/03/09 04:43:07 momjian Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -3198,7 +3198,7 @@ ShowUsage(const char *title)
 static void 
 log_disconnections(int code, Datum arg)
 {
-	Port * port = MyProcPort;
+	Port *port = MyProcPort;
 	struct timeval end;
 	int  hours, minutes, seconds;
 

src/backend/utils/error/elog.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.126 2003/11/29 19:52:01 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.127 2004/03/09 04:43:07 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -72,6 +72,7 @@ PGErrorVerbosity Log_error_verbosity = PGERROR_VERBOSE;
 bool		Log_timestamp = false;		/* show timestamps in stderr
 										 * output */
 bool		Log_pid = false;	/* show PIDs in stderr output */
+char       *Log_line_prefix = ""; /* format for extra log line info */
 
 #ifdef HAVE_SYSLOG
 /*
@@ -146,7 +147,7 @@ static const char *error_severity(int elevel);
 static const char *print_timestamp(void);
 static const char *print_pid(void);
 static void append_with_tabs(StringInfo buf, const char *str);
-
+static const char *log_line_prefix(void);
 
 /*
  * errstart --- begin an error-reporting cycle
@@ -1022,6 +1023,138 @@ write_syslog(int level, const char *line)
 }
 #endif   /* HAVE_SYSLOG */
 
+/*
+ * Format tag info for log lines 
+ */
+static const char * 
+log_line_prefix(void)
+{
+
+	/* static accumulator for line numbers */
+	static int log_line_number = 0;
+ 
+	/* space for option string + one of each option, plus some room to spare */
+	/* Note: if more identifiers are built in this will have to increase */
+	static char *result = NULL;
+	int format_len = strlen(Log_line_prefix);
+	int result_len = 2*NAMEDATALEN + format_len +120 ;
+
+	if (result == NULL)
+		result = malloc(result_len);
+	result[0] = '\0';
+
+	if (format_len > 0)
+	{
+		int i,j;
+		char * dbname = NULL;
+		char * username = NULL;
+		time_t stamp_time;
+		log_line_number++;
+		if (MyProcPort != NULL)
+		{
+			dbname  = MyProcPort->database_name;
+			username = MyProcPort->user_name;
+			if (dbname == NULL || *dbname == '\0')
+				dbname = gettext("[unknown]");
+			if (username == NULL || *username == '\0')
+				username = gettext("[unknown]");
+		}
+
+		/*
+		 * invariant through each iteration of this loop:
+		 *  . j is the index of the trailing null on result
+		 *  . result_len - j is the number of chars we have room for
+		 *    including the trailing null
+		 *  . there is room to write at least one more non-null char plus the
+		 *    trailing null
+		 */
+		for (i = 0, j=0; i < format_len && j < result_len-1; i++)
+		{
+			if(Log_line_prefix[i] != '%')
+			{
+				/* literal char, just copy */
+				result[j]=Log_line_prefix[i];
+				j++;
+				result[j] = '\0';
+				continue;
+			}
+			else if (i == format_len - 1)
+			{
+				/* format error - skip it */
+				continue;
+			}
+
+			/* go to char after '%' */
+			i++;
+
+			/* in postmaster and friends, skip non-applicable options,
+			 * stop if %x is seen
+			 */
+			if (MyProcPort == NULL)
+			{
+				if (Log_line_prefix[i] == 'x')
+					break;
+				if (strchr("udcsir",Log_line_prefix[i]) != NULL)
+					continue;
+			}
+
+			/* process the option */
+			switch (Log_line_prefix[i])
+			{
+				case 'u': 
+					j += snprintf(result+j,result_len-j,"%s",username);
+					break;
+				case 'd': 
+					j += snprintf(result+j,result_len-j,"%s",dbname);
+					break;
+				case 'c':
+					j += snprintf(result+j,result_len-j,"%lx.%lx",
+								  (long)(MyProcPort->session_start.tv_sec),
+								  (long)MyProcPid);
+					break;
+				case 'p':
+					j += snprintf(result+j,result_len-j,"%ld",(long)MyProcPid);
+					break;
+				case 'l':
+					j += snprintf(result+j,result_len-j,"%d",log_line_number);
+					break;
+				case 't':
+					stamp_time = time(NULL);
+					j += strftime(result+j, result_len-j, "%Y-%m-%d %H:%M:%S",
+							 localtime(&stamp_time));
+					break;
+				case 's':
+					j += strftime(result+j, result_len-j, "%Y-%m-%d %H:%M:%S",
+							 localtime(&(MyProcPort->session_start.tv_sec)));
+					break;
+				case 'i':
+					j += snprintf(result+j,result_len-j,"%s",
+								  MyProcPort->commandTag);
+					break;
+				case 'r':
+					j += snprintf(result+j,result_len-j,"%s",
+								  MyProcPort->remote_host);
+					if (!LogSourcePort && strlen(MyProcPort->remote_port))
+						j += snprintf(result+j,result_len-j,"(%s)",
+									  MyProcPort->remote_port);
+					break;
+				case 'x': 
+					/* non-postmaster case - just ignore */
+					break;
+				case '%': 
+					result[j] = '%';
+					j++;
+					result[j] = '\0';
+					break;
+				default:
+					/* format error - skip it */
+					break;
+			}
+		}
+	}
+	return result;
+}
+
 
 /*
  * Write error report to server's log
@@ -1033,7 +1166,8 @@ send_message_to_server_log(ErrorData *edata)
 
 	initStringInfo(&buf);
 
-	appendStringInfo(&buf, "%s:  ", error_severity(edata->elevel));
+	appendStringInfo(&buf, "%s%s:  ", 
+					 log_line_prefix(), error_severity(edata->elevel));
 
 	if (Log_error_verbosity >= PGERROR_VERBOSE)
 	{
@@ -1066,18 +1200,21 @@ send_message_to_server_log(ErrorData *edata)
 	{
 		if (edata->detail)
 		{
+			appendStringInfoString(&buf, log_line_prefix() );
 			appendStringInfoString(&buf, gettext("DETAIL:  "));
 			append_with_tabs(&buf, edata->detail);
 			appendStringInfoChar(&buf, '\n');
 		}
 		if (edata->hint)
 		{
+			appendStringInfoString(&buf, log_line_prefix() );
 			appendStringInfoString(&buf, gettext("HINT:  "));
 			append_with_tabs(&buf, edata->hint);
 			appendStringInfoChar(&buf, '\n');
 		}
 		if (edata->context)
 		{
+			appendStringInfoString(&buf, log_line_prefix() );
 			appendStringInfoString(&buf, gettext("CONTEXT:  "));
 			append_with_tabs(&buf, edata->context);
 			appendStringInfoChar(&buf, '\n');
@@ -1086,11 +1223,13 @@ send_message_to_server_log(ErrorData *edata)
 		{
 			/* assume no newlines in funcname or filename... */
 			if (edata->funcname && edata->filename)
-				appendStringInfo(&buf, gettext("LOCATION:  %s, %s:%d\n"),
+				appendStringInfo(&buf, gettext("%sLOCATION:  %s, %s:%d\n"),
+								 log_line_prefix(),
 								 edata->funcname, edata->filename,
 								 edata->lineno);
 			else if (edata->filename)
-				appendStringInfo(&buf, gettext("LOCATION:  %s:%d\n"),
+				appendStringInfo(&buf, gettext("%sLOCATION:  %s:%d\n"),
+								 log_line_prefix(),
 								 edata->filename, edata->lineno);
 		}
 	}
@@ -1100,6 +1239,7 @@ send_message_to_server_log(ErrorData *edata)
 	 */
 	if (edata->elevel >= log_min_error_statement && debug_query_string != NULL)
 	{
+		appendStringInfoString(&buf, log_line_prefix() );
 		appendStringInfoString(&buf, gettext("STATEMENT:  "));
 		append_with_tabs(&buf, debug_query_string);
 		appendStringInfoChar(&buf, '\n');

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.188 2004/02/23 20:45:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.189 2004/03/09 04:43:07 momjian Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -1495,6 +1495,16 @@ static struct config_string ConfigureNamesString[] =
 		"panic", assign_min_error_statement, NULL
 	},
 
+	{
+		{"log_line_prefix", PGC_SIGHUP, LOGGING_WHAT,
+		 gettext_noop("Controls information prefixed to each log line"),
+		 gettext_noop("if blank no prefix is used")
+		},
+		&Log_line_prefix,
+		"", NULL, NULL
+	},
+
+
 	{
 		{"DateStyle", PGC_USERSET, CLIENT_CONN_LOCALE,
 			gettext_noop("Sets the display format for date and time values."),

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

@@ -185,6 +185,14 @@
 #log_disconnections = false
 #log_duration = false
 #log_pid = false
+#log_line_prefix = ''		# e.g. '<%u%%%d> ' 
+				# %u=user name %d=database name
+				# %r=remote host and port
+				# %p=PID %t=timestamp %i=command tag
+				# %c=session id %l=session line number
+				# %s=session start timestamp
+				# %x=stop here in non-session processes
+				# %%='%'
 #log_statement = false
 #log_timestamp = false
 #log_hostname = false

src/backend/utils/misc/ps_status.c

@@ -5,7 +5,7 @@
  * to contain some useful information. Mechanism differs wildly across
  * platforms.
  *
- * $PostgreSQL: pgsql/src/backend/utils/misc/ps_status.c,v 1.17 2004/02/22 21:26:55 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/misc/ps_status.c,v 1.18 2004/03/09 04:43:07 momjian Exp $
  *
  * Copyright (c) 2000-2003, PostgreSQL Global Development Group
  * various details abducted from various places
@@ -26,6 +26,7 @@
 #include <crt_externs.h>
 #endif
 
+#include "libpq/libpq.h"
 #include "miscadmin.h"
 #include "utils/ps_status.h"
 
@@ -276,11 +277,16 @@ init_ps_display(const char *username, const char *dbname,
 void
 set_ps_display(const char *activity)
 {
-#ifndef PS_USE_NONE
 	/* no ps display for stand-alone backend */
 	if (!IsUnderPostmaster)
 		return;
 
+	/* save it for logging context */
+	if (MyProcPort)
+		MyProcPort->commandTag = (char *) activity;
+
+#ifndef PS_USE_NONE
+
 #ifdef PS_USE_CLOBBER_ARGV
 	/* If ps_buffer is a pointer, it might still be null */
 	if (!ps_buffer)

src/include/libpq/libpq-be.h

@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/libpq/libpq-be.h,v 1.41 2004/02/21 06:29:58 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/libpq/libpq-be.h,v 1.42 2004/03/09 04:43:07 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -50,6 +50,7 @@ typedef struct Port
 	SockAddr	raddr;			/* remote addr (client) */
 	char        *remote_host;   /* name (or ip addr) of remote host */
 	char        *remote_port;   /* text rep of remote port */
+	char        *commandTag;    /* command tag for display in log lines */
 	struct timeval  session_start;  /* for session duration logging */
 	CAC_state	canAcceptConnections;	/* postmaster connection status */
 

src/include/utils/elog.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/elog.h,v 1.64 2003/11/29 22:41:15 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/utils/elog.h,v 1.65 2004/03/09 04:43:07 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -171,6 +171,7 @@ typedef enum
 extern PGErrorVerbosity Log_error_verbosity;
 extern bool Log_timestamp;
 extern bool Log_pid;
+extern char *Log_line_prefix;
 
 #ifdef HAVE_SYSLOG
 extern int	Use_syslog;