title: How can I change an index defined on a table?
body: <p>I have an index defined like    </p>
  
  <pre><code>add_index :users, :email, :unique =&gt; true
  </code></pre>
  
  <p>Is there any way to change this index to drop the UNIQUE constraint, something like 'change_index'?<br>
  Or is it the only way to drop the index and add it again without the UNIQUE constraint?</p>