title: Deleting duplicate rows from sqlite database
body: <p>I have a huge table - 36 million rows - in SQLite3. In this very large table, there are two columns:</p>
  
  <ul>
  <li><code>hash</code> - text</li>
  <li><code>d</code> - real</li>
  </ul>
  
  <p>Some of the rows are duplicates. That is, both <code>hash</code> and <code>d</code> have the same values. If two hashes are identical, then so are the values of <code>d</code>. However, two identical <code>d</code>'s does not imply two identical <code>hash</code>'es.</p>
  
  <p>I want to delete the duplicate rows. I don't have a primary key column.</p>
  
  <p>What's the fastest way to do this?</p>