如何使用Django-nonrel的MongoDB mapreduce？

Question

I'm just learning how to use Mapreduce and reading this documentation: http://django-mongodb.org/topics/mapreduce.html

But it says: MongoDB's Map/Reduce is designed for one-time operations, ie it's not intended to be used in code that is executed on a regular basis (views, business logic, ...).

My question is right now: Where DO I use it? Are there any recommendations or something? I really can't find it.

Thanks a lot!

Answer 1

It's difficult to predict how long mapreduce functions take (assuming you have large data), so they're a bad choice for say doing processing that is required to generate a web page view that many users often use.

It's useful for doing data analysis on your data, where you're willing to wait to get a result. It's also useful for operating on large sets of data, like processes for updating every document in your database.