Note the same pattern again and again, in theory with a relational database the list of following and followers is a single table with fields like following_id and follower_id. With queries you can extract the followers or following of every user. With a key-value DB that’s a bit different as we need to set both the 1000 is following 1001 and 1001 is followed by 1000 relations. This is the price to pay, but on the other side accessing the data is simpler and ultra-fast.
