title: Setting enable_seqscan = off in a single SELECT query
body: <p>After several tests on one of my queries (Postgres) I realized that by setting <code>enable_seqscan</code> = off, the query takes 1/3 of its original time (done using the <code>psql</code> console and <code>EXPLAIN ANALYZE</code>)</p>
  
  <p>Since it is not recommendable to change this setting for the whole server, I want to set it to <code>OFF</code> only for this query.<br>
  How can I do it? Is it possible?</p>
  
  <p>My implementation is based on framework Kohana (PHP), which uses a DB object ( DB::select ) to execute the query.</p>
  
  <p>My postgres is 8.4.9 on a CentOS Linux.</p>