Can someone please review the design for notification system ? Also How can we handle different priority of notification?

Database choices:
1. Notification DB -> This will be any relational database because i have structured data and i want to query based on sender, receiver, status.
2. Message Type based DBs -> I will go with NoSql databases and i will prefer Dynamo here.
3. Monitoring DB -> Time-Series Database

Feedbacks are welcome.