It has been suggested on Amazon docs http://aws.amazon.com/dynamodb/ among other places, that you can backup your dynamodb tables using Elastic Map Reduce,
I have a general understanding of how this could work but I couldn't find any guides or tutorials on this,

So my question is how can I automate dynamodb backups (using EMR)?

So far, I think I need to create a "streaming" job with a map function that reads the data from dynamodb and a reduce that writes it to S3 and I believe these could be written in Python (or java or a few other languages).

Any comments, clarifications, code samples, corrections are appreciated.