Currently we have no real counts as to how many listens we have in the system or how many listens a user has. To fix this we could use redis in the following manner:

1) Set up redis and have keys for each user and one key for a global count
2) Have the cassandra writer update the counts in redis on the fly. Note the timestamp on which this this new updated writer was started. Keep this value in redis as well.
3) Have a replay script traverse the data in cassandra from beginning of time up until, but exclusive of the timestamp stored in redis from step 2. This script updates the same counts as 2.
4) Once the script is caught up, the counts in redis should be accurate and can be displayed on the site.