title: mysql speed, table index and select/update/insert
body: <p>We have got a MySQL table which has got more than 7.000.000 (yes seven million) rows.
  We are always doing so much SELECT / INSERT / UPDATE queries per 5 seconds.</p>
  
  <p>Is it a good thing that if we create MySQL INDEX for that table? Will there be some bad consequences like data corrupting or loosing MySQL services etc.?</p>
  
  <p>Little info:</p>
  
  <ul>
  <li>MySQL version 5.1.56</li>
  <li>Server CentOS</li>
  <li>Table engines are MyISAM</li>
  <li>MySQL CPU load between 200% - 400% always</li>
  </ul>