SQL to MongoDB: An Updated Mapping from Kristina Chodorow.
From the post:
The aggregation pipeline code has finally been merged into the main development branch and is scheduled for release in 2.2. It lets you combine simple operations (like finding the max or min, projecting out fields, taking counts or averages) into a pipeline of operations, making a lot of things that were only possible by using MapReduce doable with a “normal” query.
In celebration of this, I thought I’d re-do the very popular MySQL to MongoDB mapping using the aggregation pipeline, instead of MapReduce.
If you are interested in MongoDB-based solutions, this will be very interesting.