title: Indexes, why don't just index everything and when to use indexes?
body: <blockquote>
    <p>Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. </p>
  </blockquote>
  
  <p>Says our beloved <a href="http://dev.mysql.com/doc/refman/5.0/en/mysql-indexes.html" rel="noreferrer">MySQL manual</a>.</p>
  
  <p>In that case, <strong>why don't just index every column?</strong></p>
  
  <p>And since I have this feeling that it would be a bigger hit to performance, <strong>when should we use indexes/best practices for indexes</strong>?</p>
  
  <p>Thanks in advance!</p>