If you're using Django-nonrel on Google App Engine, mapreduce will not work out of the box. I put a bit of work getting it running. Fortunately, I was not the first. This blog post suggests some code to get you started and allow you to run a mapper on all of our entities. Unfortunately it only allows you to map app engine entities, not Django entities. The code below fixes that issue. It works in a similar way, but performs a Django "get" before running the mapper to convert a key into a Django entity. This adds a bit more overhead; one more get per map.