diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
new file mode 100644
index e826c19..bec9483
*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
*************** local0.*    /var/log/postgresql
*** 5004,5010 ****
           value will pad on the left. Padding can be useful to aid human
           readability in log files.
           This parameter can only be set in the <filename>postgresql.conf</>
!          file or on the server command line. The default is an empty string.
  
           <informaltable>
            <tgroup cols="3">
--- 5004,5011 ----
           value will pad on the left. Padding can be useful to aid human
           readability in log files.
           This parameter can only be set in the <filename>postgresql.conf</>
!          file or on the server command line. The default is
!          <literal>%m [%p] </> which logs a time stamp and the process ID.
  
           <informaltable>
            <tgroup cols="3">
*************** FROM pg_stat_activity;
*** 5142,5147 ****
--- 5143,5159 ----
           include those escapes if you are logging to <application>syslog</>.
          </para>
         </tip>
+ 
+        <tip>
+         <para>
+          The <literal>%q</> escape is useful when including information that is
+          only available in session (backend) context like user or database
+          name. An example would be:
+ <programlisting>
+ log_line_prefix = '%m [%p] %q%u@%d/%a '
+ </programlisting>
+         </para>
+        </tip>
        </listitem>
       </varlistentry>
  
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
new file mode 100644
index 622279b..65660c1
*** a/src/backend/utils/misc/guc.c
--- b/src/backend/utils/misc/guc.c
*************** static struct config_string ConfigureNam
*** 3014,3020 ****
  			gettext_noop("If blank, no prefix is used.")
  		},
  		&Log_line_prefix,
! 		"",
  		NULL, NULL, NULL
  	},
  
--- 3014,3020 ----
  			gettext_noop("If blank, no prefix is used.")
  		},
  		&Log_line_prefix,
! 		"%m [%p] ",
  		NULL, NULL, NULL
  	},
  
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
new file mode 100644
index 05b1373..159ada3
*** a/src/backend/utils/misc/postgresql.conf.sample
--- b/src/backend/utils/misc/postgresql.conf.sample
***************
*** 430,436 ****
  #log_duration = off
  #log_error_verbosity = default		# terse, default, or verbose messages
  #log_hostname = off
! #log_line_prefix = ''			# special values:
  					#   %a = application name
  					#   %u = user name
  					#   %d = database name
--- 430,436 ----
  #log_duration = off
  #log_error_verbosity = default		# terse, default, or verbose messages
  #log_hostname = off
! #log_line_prefix = '%m [%p] '		# special values:
  					#   %a = application name
  					#   %u = user name
  					#   %d = database name