title: How do I reduce MySQL's overhead as displayed in phpMyAdmin?
body: <p>In my MySQL database I see these statistics:</p>
  
  <pre><code>Type    Usage  
  Data    16,384  Bytes  
  Index   32,768  Bytes  
  Overhead    405,0   MB  
  Effective   -424,624,128    Bytes  
  Total   49,152  Bytes  
  </code></pre>
  
  <p>When I try the commands <code>check table</code>, <code>ALTER TABLE  'mytable' ENGINE = INNODB</code>, <code>OPTIMIZE TABLE</code>, nothing happens to the overhead.</p>
  
  <p>Why does nothing happen, should I worry, and when should I worry? I've seen other questions that state 'to worry when the overhead gets too large'. What is too large?</p>