title: Email address as select index in mysql for huge table query speed
body: <p>I'm wondering about using emails for indexing. I realise that this is sub-optimal and that it's better to use an auto-incremented primary key. But in this case I'm trying to develop a lite application that does not require account registration to use.</p>
  
  <pre><code>SELECT account_id, account_balance, account_payments_received
  FROM accounts
  WHERE account_email = ?
  LIMIT 1
  </code></pre>
  
  <p>This works ok at the moment with few users. But I'm concerned about when it reaches a million or more. Is there any way to index emails quickly?</p>
  
  <p>I was thinking maybe I could use the first and second characters as keys? Maybe develop an index number for a=1, b=2, c=3 and so on.....</p>
  
  <p>What do you guys suggest?</p>