Essentially column families should have the same keys. If you want to use two different keys you need two tables. So I think you should have two tables, one keyed by account|cust as you say to find the customer info for an account and a separate table that is cust|account so you can easily drill down to a customer and find all the accounts associated with it. You can also do the second table with cust as key and then an array of accounts as you say but then you always need to update the list of accoiunts at a time. If you key the second table by cust|account you can freely add delete account rows for a customer and do a scan to get all accounts. ... View more