The Comments Conundrum by Kristina Chodorow.
From the post:
One of the most common questions I see about MongoDB schema design is:
I have a collection of blog posts and each post has an array of comments. How do I get…
…all comments by a given author
…the most recent comments
…the most popular commenters?And so on. The answer to this has always been “Well, you can’t do that on the server side…” You can either do it on the client side or store comments in their own collection. What you really want is the ability to treat embedded documents like a “real” collection.
The aggregation pipeline gives you this ability by letting you “unwind” arrays into separate documents, then doing whatever else you need to do in subsequent pipeline operators.
Kristina continues her coverage of the aggregation pipeline in MongoDB.
Question: What is the result of an aggregation? (In a topic map sense?)