title: does redis pub sub persist historical messages in a channel?
body: <p>I haven't been able to find in the documentation on how the messages in a channel get stored in redis publish/subscribe.</p>
  
  <p>When you publish to a redis channel, is that message stored or persisted?  If so, how long is it stored and how do you get historical messages?</p>
  
  <p>Otherwise, I'm assuming that it just broadcasts that message and drops/deletes that message after doing so?</p>