Set the correct context (PGC_SIGHUP) for log_autovacuum, per ITAGAKI Takahiro.

Fix grammatical errors in its description.

doc/src/sgml/config.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.142 2007/09/05 18:10:47 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.143 2007/09/10 01:39:19 tgl Exp $ -->
 
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -3406,10 +3406,10 @@ guess what
       </indexterm>
       <listitem>
        <para>
-        Causes actions executed by autovacuum to be logged if it ran for at
-        least the specified number of milliseconds.  Setting this to zero prints
-        all action durations. Minus-one (the default) disables logging
-        autovacuum action durations.  For example, if you set it to
+        Causes each action executed by autovacuum to be logged if it ran for at
+        least the specified number of milliseconds.  Setting this to zero logs
+        all autovacuum actions. Minus-one (the default) disables logging
+        autovacuum actions.  For example, if you set this to
         <literal>250ms</literal> then all vacuums and analyzes that run
         250ms or longer will be logged.  Enabling this parameter can be helpful
         in tracking autovacuum activity.  This setting can only be set in

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 1.417 2007/09/10 00:57:21 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.418 2007/09/10 01:39:19 tgl Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -1573,10 +1573,10 @@ static struct config_int ConfigureNamesInt[] =
 	},
 
 	{
-		{"log_autovacuum", PGC_BACKEND, LOGGING_WHAT,
+		{"log_autovacuum", PGC_SIGHUP, LOGGING_WHAT,
 			gettext_noop("Sets the minimum execution time above which autovacuum actions "
 						 "will be logged."),
-			gettext_noop("Zero prints all actions.  The default is -1 (turning this feature off)."),
+			gettext_noop("Zero prints all actions.  The default is -1 (disabling autovacuum logging)."),
 			GUC_UNIT_MS
 		},
 		&Log_autovacuum,