title: Datadog unit of time for monitor time aggregation
body: <p>I've been trying to understand the time aggregation for Datadog monitoring alerts. The official doc <a href="http://docs.datadoghq.com/guides/monitors/#define-the-conditions" rel="nofollow noreferrer">http://docs.datadoghq.com/guides/monitors/#define-the-conditions</a>
  I understand the idea of time aggregation, but I'm confused about the unit of time as it's not mentioned anywhere. Is it aggregating over 1 minute intervals? 
  To rephrase this when I use <code>sum(last_30m){X}</code> is it summing the values of <code>X</code> for each minute? What about <code>sum(last_1h){X}</code>? Is it still each minute?</p>