title: Index on MySQL field not working as expected (innodb)
body: <p>I have 30 millions records and one field (updated) is a tinyint(1) with an index.</p>
  
  <p>If I run:</p>
  
  <pre><code>SELECT * FROM  `table` WHERE `updated` = 1
  </code></pre>
  
  <p>It will take an increasingly long time depending on how many are set to 1.
  If it is say 10,000 it will be quite fast about 1 second. However if there is say 1 million it takes a couple of minutes. </p>
  
  <p>Isn't the index suppose to make this fast?</p>
  
  <p>When I run the same query on a non-indexed field that is similar only it is int(1) it performs the same as the indexed field.</p>
  
  <p>Any ideas as to why this would be? is tinyint bad?</p>