To demonstrate this approach, we'll start by creating a new table, user_follows, that has an identical structure to our user_inbound_follows table:
CREATE TABLE "user_follows" ( "followed_username" text, "follower_username" text, PRIMARY KEY ("followed_username", "follower_username") );
As with user_outbound_follows, this new table uses a followed user as its partition key and the follower as its clustering column. At a higher level, for each user, U, this table stores a partition of rows representing the users that follow U. So, if we'd like to find out who follows a given user, we can do so very efficiently using this table.
However, we've said that we want to use the same table for both inbound and outbound ...
