Let's say we have a website like youtube where we have a comment session per e video. Users want to be able to comment and to see the comments made by other users by comment creation time. This is relatively easy to shard when you know there will be just a small amount of comments per video or you have a limit on the amount of comments per video. But how can we shard these comments when there growth is unbounded?
I have found very few information about this problem. https://medium.com/@foundev/synthetic-sharding-in-cassandra-to-deal-with-large-partitions-2124b2fd788b