Adding a new field to 100 million records in mongodb
<p>What is the fastest and safest strategy for adding a new field to over 100 million mongodb documents?</p>

<p>Background</p>

<ul>
<li><p>Using mongodb 3.0 in a 3 node replica set</p></li>
<li><p>We are adding a new field (post_hour) that is based on data in another field (post_time) in the current document. The post_hour field is a truncated version of post_time to the hour.</p></li>
</ul>