title: Force MySQL to use two indexes on a Join
body: <p>I am trying to force MySQL to use two indexes. I am joining a table and I want to utilize the cross between the two indexes. The specific term is Using intersect and here is a link to MySQL documentation: </p>
  
  <p><a href="http://dev.mysql.com/doc/refman/5.0/en/index-merge-optimization.html" rel="noreferrer">http://dev.mysql.com/doc/refman/5.0/en/index-merge-optimization.html</a></p>
  
  <p>Is there any way to force this implementation? My query was using it (and it sped stuff up), but now for whatever reason it has stopped.</p>
  
  <p>Here is the JOIN I want to do this on. The two indexes I want the query to use are scs.CONSUMER_ID_1 and scs_CONSUMER_ID_2</p>
  
  <pre><code>JOIN survey_customer_similarity AS scs
      ON cr.CONSUMER_ID=scs.CONSUMER_ID_2 
      AND cal.SENDER_CONSUMER_ID=scs.CONSUMER_ID_1 
      OR cr.CONSUMER_ID=scs.CONSUMER_ID_1 
      AND cal.SENDER_CONSUMER_ID=scs.CONSUMER_ID_2
  </code></pre>