title: ActiveRecord: find_by_sql and includes
body: <p>I would like to use find_by_sql and includes at the same time.</p>
  <p>I use find_by_sql because I write select inside from to utilize index.
  Somehow, index is ignored if I use left join.</p>
  <p>But, find_by_sql does not return ActiveRecord_Relation but returns Array objects, so I cannot write</p>
  <pre><code>like Model.find_by_sql(&quot;select * from (select * from table limit 10)table left join rel_table on ...&quot;).includes(:rel_table,...) .
  </code></pre>
  <p>I can run two queries and hand-includes after that.
  Is there any way to solve it as one SQL?</p>