title: Proper way to create dynamic 1:M SQL table
body: <p>Simplified example:  Two tables - people and times.  Goal is to keep track of all the times a person walks through a doorway.  </p>
  
  <p>A person could have between 0 and 50 entries in the times table daily.  </p>
  
  <p>What is the proper and most efficient way to keep track of these records?  Is it</p>
  
  <pre><code>times table
  -----------
  person_id
  timestamp
  </code></pre>
  
  <p>I'm worried that this table can get well over a million records rather quickly.  Insertion and retrieval times are of utmost importance.  </p>
  
  <p>ALSO: Obviously non-normalized but would it be a better idea to do</p>
  
  <pre><code>times table
  -----------
  person_id
  serialized_timestamps_for_the_day
  date
  </code></pre>
  
  <p>We need to access each individual timestamp for the person but ONLY query records on date or the person's id.</p>