When do I use Google's MapReduce

Question

I recently stumbled upon Google's MapReduce.

I have read the description / docs twice, and I still can not understand what exactly it is, or when to use it.

Thank you very much.

Answer 1

Google App Engine provides you with an API (java and python) for running MapReduce Jobs on their App Engine. Although you cannot view all the source code (modules like scheduler, job tracker, task tracker, etc), you can view the source code for the API (which includes mappers, reducers, partitioner etc.). GAE also provides you with a Software Development Kit (SDK) on which you can test your application. After you're satisfied with your app's performance, you can then upload it on GAE and anyone can access it.

I have made one such app, its found at shaileshmapreduce.appspot.com. It won't let you run a MapReduce job, because I'll have to add your gmail id into the user list, but you can check out the interface and everything.

You can also try out their MapReduce demo https://developers.google.com/appengine/docs/python/dataprocessing/helloworld

Of course, you need to make sure that you have the SDK and the required MapReduce library installed on your machine.