title: Pros and Cons of using Redis vs memcached+db as Django's session system?
body: <p>Django's builtin cached_db session allows me to use memcached to store session data, and write through to db for persistence.</p>
  
  <p>While some applications use redis as their session store (instagram for one).</p>
  
  <p>What is the pros and cons of these solutions?</p>
  
  <p>p.s. I am not asking about the comparison between memcached and redis, which this question <a href="https://stackoverflow.com/questions/10558465/memcache-vs-redis">Memcached vs. Redis?</a> already provides very good answers. I am asking about which one is better in case of a session system.</p>