title: Use email address as primary key?
body: <p>Is email address a bad candidate for primary when compared to auto incrementing numbers?</p>
  
  <p>Our web  application needs the email address to be unique in the system. So, I thought of using email address as primary key. However my colleague suggests that string comparison will be slower than integer comparison. </p>
  
  <p>Is it a valid reason to not use email as primary key?</p>
  
  <p>We are using <code>PostgreSQL</code>.</p>