title: Clarification on MySQL 5.6 using IN PLACE alter table for adding/dropping the same index
body: <p>From the docs:</p>
  
  <blockquote>
    <p>An ALTER TABLE statement that contains DROP INDEX and ADD INDEX
    clauses that both name the same index uses a table copy, not Fast
    Index Creation.</p>
  </blockquote>
  
  <p>This is a bit unclear to me. Is it talking about the NAME of the index? Can someone give an example of a query in which MySQL resorts to a table copy?</p>