title: Getting rid of "Using temporary; Using filesort"
body: <p>When I do an explain on my query </p>
  
  <p><img src="https://i.stack.imgur.com/7JQPk.png" alt="enter image description here"></p>
  
  <p>I see that it has "Using temporary; Using filesort" under "Extra" for the first row. I understand this is bad but I don't know what exactly it means or how to fix it.</p>
  
  <p>If you want to see my query, here's a more general question I asked about the same query: <a href="https://stackoverflow.com/questions/4934614/mysql-query-optimization-and-explain-for-a-noob">MySQL query optimization and EXPLAIN for a noob</a>.
  For reference, the query involves 24 tables and 23 joins.</p>
  
  <p>My questions now are:</p>
  
  <ul>
  <li>What do "Using temporary" and "Using filesort" mean?</li>
  <li>Assuming they're bad, how do I get rid of them?</li>
  </ul>