title: Should Dataflow consume events from a Pub/Sub topic or subscription?
body: <p>I am looking to stream events from from PubSub into BigQuery using Dataflow. I see that there are two templates for doing this in GCP: one where Dataflow reads messages from a topic; and one from a subscription. </p>
  
  <p>What are the advantages of using a subscription here, rather than just consuming the events from the topic?</p>