title: Is it possible to specify what index a query should use in Mongoid?
body: <p>MongoDB seems like it is using an inefficient query pattern when one index is a subset of another index.</p>
  
  <pre><code>class Model
    field :status, :type =&gt; Integer
    field :title, :type =&gt; String
    field :subtitle, :type =&gt; String
    field :rating, :type =&gt; Float
  
    index([
      [:status, Mongo::ASCENDING],
      [:title, Mongo::ASCENDING],
      [:subtitle, Mongo::ASCENDING],
      [:rating, Mongo::DESCENDING]
    ])
    index([
      [:status, Mongo::ASCENDING],
      [:title, Mongo::ASCENDING],
      [:rating, Mongo::DESCENDING]
    ])
  end
  </code></pre>
  
  <p>The first index is being used both when querying on <code>status</code>, <code>title</code> and <code>subtitle</code> and sorting on <code>rating</code> and when querying on just <code>status</code> and <code>title</code> and sorting on <code>rating</code> even though using <code>explain()</code> along with <code>hint()</code> in the javascript console states that using the second index is 4 times faster.</p>
  
  <p>How can I tell Mongoid to tell MongoDB to use the second index?</p>