title: What is the return value of update_all() in ActiveRecord / Ruby on Rails?
body: <p>The Ruby on Rails and ActiveRecord documentation, Google, and StackOverflow are conspiratorially silent on the return value of update_all()</p>
  
  <p>What does update_all() return? </p>
  
  <ul>
  <li>Number of records? </li>
  <li>Success status? </li>
  <li>ID's of updated records?</li>
  </ul>