Marginal improvements in the wording of the autovacuum documentation:

be consistent about whether it's called a daemon or a subprocess, and
don't describe the autovacuum setting in exactly the same way as the
stats_start_collector setting, because that leaves people thinking (if
they aren't paying close attention) that autovacuum can't be changed
on the fly.

doc/src/sgml/config.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.43 2006/01/11 23:14:29 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.44 2006/01/21 19:34:42 tgl Exp $
 -->
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -867,9 +867,9 @@ SET ENABLE_SEQSCAN TO OFF;
         Sets the maximum number of disk pages for which free space will
         be tracked in the shared free-space map.  Six bytes of shared memory
         are consumed for each page slot.  This setting must be more than
-        16 * <varname>max_fsm_relations</varname>.  The default is 20000,
-		but <application>initdb</> will try to set it as close as possible 
-		to 200000, depending on the amount of available memory.
+        16 * <varname>max_fsm_relations</varname>.  The default is chosen
+        by <application>initdb</> depending on the amount of available memory,
+        and can range from 20000 to 200000.
         This option can only be set at server start.
        </para>
       </listitem>
@@ -2825,8 +2825,11 @@ SELECT * FROM parent WHERE key = 2400;
         Controls whether the server should start the
         statistics-collection subprocess.  This is on by default, but
         may be turned off if you know you have no interest in
-        collecting statistics.  This option can only be set at server
-        start.
+        collecting statistics or running autovacuum.
+        This option can only be set at server start, because the collection
+        subprocess cannot be started or stopped on-the-fly.  (However, the
+        extent to which statistics are actually gathered can be changed while
+        the server is running, so long as the subprocess exists.)
        </para>
       </listitem>
      </varlistentry>
@@ -2909,12 +2912,12 @@ SELECT * FROM parent WHERE key = 2400;
 
     <indexterm>
      <primary>autovacuum</primary>
-     <secondary>global configuration parameters</secondary>
+     <secondary>configuration parameters</secondary>
     </indexterm>
 
      <para>
-      These settings control the default behavior for the <firstterm>autovacuum
-      daemon</firstterm>. Please refer to <xref linkend="autovacuum"> for
+      These settings control the behavior of the <firstterm>autovacuum</>
+      feature. Please refer to <xref linkend="autovacuum"> for
       more information.
      </para>
 
@@ -2927,10 +2930,10 @@ SELECT * FROM parent WHERE key = 2400;
       </indexterm>
       <listitem>
        <para>
-        Controls whether the server should start the
-        autovacuum subprocess.  This is off by default.
+        Controls whether the server should run the
+        autovacuum daemon.  This is off by default.
         <varname>stats_start_collector</> and <varname>stats_row_level</>
-        must also be on for this to start.
+        must also be turned on for autovacuum to work.
         This option can only be set at server start or in the
         <filename>postgresql.conf</filename> file.
        </para>
@@ -2945,7 +2948,7 @@ SELECT * FROM parent WHERE key = 2400;
       <listitem>
        <para>
         Specifies the delay between activity rounds for the autovacuum
-        subprocess.  In each round the subprocess examines one database
+        daemon.  In each round the daemon examines one database
         and issues <command>VACUUM</> and <command>ANALYZE</> commands
         as needed for tables in that database.  The delay is measured
         in seconds, and the default is 60.