title: How to figure out when a SQL query will end?
body: <p>Is there any way to figure out when a SQL query will <strong>end</strong> after it starts? In other words, is there any way to figure out how much time a query will take before query execution? (<em>rough</em> estimate is fine!)</p>
  
  <pre><code>ALTER IGNORE TABLE mytbl ADD UNIQUE (c);
  </code></pre>
  
  <p>I ran this query on innodb table that has 35 million records. <code>c</code> is varchar(255)</p>
  
  <p>This command has been running for 10 hours and it still is running. I don't want to cancel if I'm close to the end. </p>
  
  <p>I appreciate any help. Thank you!</p>