Hi,

> I have written my custom partitioner for partitioning datasets. I want  to
> partition two datasets using the same partitioner and then in the  next
> mapreduce job, I want each mapper to handle the same partition from  the two
> sources and perform some function such as joining etc. How I  can I ensure that
> one mapper gets the split that corresponds to same  partition from both the
> sources?
>

Not really an answer to your specific question, but have you taken a
look at Pig (http://hadoop.apache.org/pig) which is suitable for
operations like Joining data sets ?