Using Redis to keep track of who to send notifications.
Right now I have been dealing with the need to send users a daily notification email of relevant activity.
For now this activity is limited to, other users starting to follow their data stream. Besides just notifying a user, who is following them, we also want to tell them which categories of data people are following. Only users who gotten a new follow should ever get an email.
So what do we need to know?
- Which users have received a new follow since the last round of notifications.
- Which follower(s) have started following each users.
- Which categories have each follower started following
