[MapReduce-user] Need 0.20.2 new API documentation/examples, where are they?

John,
Examples and libraries are rewritten to use new api in branch 0.21. You can have a look at them.
New api in branch 0.20 is not stable yet. And old api is undeprecated in branch 0.21. So, you can use old api still.

Thanks
Amareshwari

On 3/30/11 11:38 PM, "John Therrell" wrote:

I'm looking to get acquainted with the new API in 0.20.2 but all the online documentation I've found uses the old API.

I need to understand how to chain two mapreduce jobs together efficiently that must run sequentially. I'd like to use the SequenceFileOutputFormat --> SequenceFileInputFormat configuration between my two MapReduce jobs.

I would be so grateful for any help or links to relevant documentation/examples.

Thanks,
John

Simplest answer:

Job A uses o.a.h.mapreduce.lib.output.SequenceFileOutputFormat
It writes values to that (using context.write()) of classes KT, VT
Use o.a.h.mapreduce.lib.output.FileOutputFormat.setOutputPath(job, new
Path("job-a-out")); to configure the job to write to some location.

Then run job.waitForCompletion(true);
If the job succeeds (the above returns true), then run Job B:

Job jobB = new Job();
Job B uses FileInputFormat.addInputPath(jobB, new Path("job-a-out"); // Job
A's out is Job B's in.
jobB.setInputFormatClass(SequenceFileInputFormat.class)

Job B's mapper will then receive (K, V) arguments with classes KT and VT

Hope this helps...
- Aaron