title: How do I expire keys in dynamoDB with Boto?
body: <p>I'm trying to move from redis to dynamoDB and sofar everything is working great!  The only thing I have yet to figure out is key expiration.  Currently, I have my data setup with one primary key and no range key as so:</p>
  
  <pre><code>{
    "key" =&gt; string,
    "value" =&gt; ["string", "string"],
    "timestamp" =&gt; seconds since epoch
  }
  </code></pre>
  
  <p>What I was thinking was to do a scan over the database for where timestamp is less than a particular value, and then explicitly delete them.  This, however, seems extremely inefficient and would use up a ridiculous number of read/write units for no reason!  On top of which, the expirations would only happen when I run the scan, so they could conceivably build up.</p>
  
  <p>So, has anyone found a good solution to this problem?</p>