Gil,

This is a very helpful article. Thank you so much! I have a question, though. I’m wondering what the benefits are of duplicating the data vs. simply storing keys where duplication is needed? If a user creates a new post, for example, and needs to duplicate that data in several places (i.e. all of his followers’ feeds, his profile posts, his recent posts, etc…), wouldn’t it make more sense to put the main data in one place (“posts/${postId}”), then have each of the other groups just add the key-value pair (“feeds/{$friendId}/{ $postId : true}”) to its respective list? It seems like that would assure that each place is receiving the same data, and keeps the data updated in one place. I realize writing all of the data to each of those places would save time on the read, but it seems like the potential for update errors is considerably higher. I’m just curious.