title: Rule not fired after update statement in postgresql
body: <p>Following the guide in <a href="http://www.postgresql.org/docs/8.2/static/rules-update.html" rel="nofollow">www.postgresql.org</a></p>
  
  <p>I created this statement:</p>
  
  <pre><code>CREATE TABLE shoelace_log (
  sl_name    text,          -- shoelace changed
  sl_avail   integer,       -- new available value
  log_who    text,          -- who did it
  log_when   timestamp      -- when);
  CREATE RULE log_shoelace AS ON UPDATE TO shoelace_data
  WHERE NEW.sl_avail &lt;&gt; OLD.sl_avail
  DO INSERT INTO shoelace_log VALUES (
                                  NEW.sl_name,
                                  NEW.sl_avail,
                                  current_user,
                                  current_timestamp
                              );
  </code></pre>
  
  <p>When i try to execute the query in pgAdmin3 query console:</p>
  
  <pre><code>UPDATE shoelace_data SET sl_avail = 6 WHERE sl_name = 'sl7';
  </code></pre>
  
  <p>Only the update query are executed, and the rule isn't fired. I try to use the command EXPLAIN to understand why.</p>
  
  <pre><code>EXPLAIN UPDATE shoelace_log SET sl_avail = 6 WHERE sl_name = 'sl7';
  </code></pre>
  
  <p>The log says:</p>
  
  <pre><code>"Seq Scan on shoelace_log  (cost=0.00..19.66 rows=4 width=32)"
  "  Filter: (sl_name = 'sl7'::text)"
  "Seq Scan on shoelace_log  (cost=0.00..19.62 rows=4 width=78)"
  "  Filter: (sl_name = 'sl7'::text)"
  </code></pre>
  
  <p>I also try to use VERBOSE option with EXPLAIN, but i can't understand why my event isn't trigged.</p>