The current data model described as table name: ((partition_key),cluster_key),other_column1,other_column2,...
user_by_name: ((time_bucket, username)),ts,request,email
user_by_mail: ((time_bucket, email)),ts,request,username
The reason that all 2 keys (username, email) repeated in all tables is that there may be different username with the same email or different email with same username, and the query for data model is:
1. username = X
3. username = X and mail= Y (we query one of tables and because there is small number of records in result, we filter the other column)
This data model results in wasting lots of storage.
I thought using UUID or hash code or sequence to handle this but i can't keep track of the old vs new records (the ones that already have UUID).
Any recommendation on optimizing data model to save storage?