Implement sorted merge join

[raronson]

If both data sets are stored sorted on the join key, then its possible to perform the join on the map side. The general idea is to:

• Build up an index of keys to file location/offset of one of the data sets.
• Use the other data set as normal input to a map job.
• For each key, look up the the corresponding file/offset from the index.
• Directly read the file, seeking to the offset.

There are already implementations in both pig and hive, and would be a nice addition to scoobi.

Pigs implementation - http://wiki.apache.org/pig/PigMergeJoin
Hives implementation - https://issues.apache.org/jira/browse/HIVE-1194

[kdarshit999]

i need code to implement sort merge join any suggestions ?