title: pg_search exact match of search terms
body: <p>When trying to find "Harrison Ford" in a document, pg_search will return any text that contains 'Harrison' and 'Ford', for example:</p>
  
  <pre><code>  pg_search_scope :search_by_full_name, :against =&gt; [:first_name, :last_name]
  </code></pre>
  
  <p><em>People.search_by_full_name("Harrison Ford")</em></p>
  
  <p>can return:</p>
  
  <blockquote>
    <p>George Harrison drives a Ford Focus</p>
  </blockquote>
  
  <p>How can I make sure only exact matches of <code>'Harrison Ford'</code> will return?</p>