title: Performance of MySQL `ALTER TABLE ADD COLUMN AFTER COLUMN` - on a large table
body: <p>I want to achieve the following use the following command to add a column to an existing table:</p>
  <pre><code>ALTER TABLE foo ADD COLUMN bar AFTER COLUMN old_column;
  </code></pre>
  <p>Can this option take substantially longer than the same command without the <code>AFTER COLUMN</code> option, as follows?</p>
  <pre><code>ALTER TABLE foo ADD COLUMN bar;
  </code></pre>
  <p>Will the first command use a greater amount of <em>tmp table</em> space during execution to perform the action?</p>
  <p>Context: I have a very large table (think over a billion rows) and I want to add an additional column using the <code>AFTER COLUMN</code> option, but I don't want to be penalized too much.</p>