Fragment Replicate Join

                 Key: PIG-554
             Project: Pig
          Issue Type: New Feature
    Affects Versions: types_branch
            Reporter: Shravan Matthur Narayanamurthy
             Fix For: types_branch

Fragment Replicate Join(FRJ) is useful when we want a join between a huge table 
and a very small table (fitting in memory small) and the join doesn't expand 
the data by much. The idea is to distribute the processing of the huge files by 
fragmenting it and replicating the small file to all machines receiving a 
fragment of the huge file. Because of the availability of the entire small 
file, the join becomes a trivial task without needing any break in the 
pipeline. Exhaustive test have done to determine the improvement we get out of 
FRJ. Will post the details in a wiki and add a link here

The patch makes changes to parts of the code where new operators are 
introduced. Currently, when a new operator is introduced, its alias is not set. 
For schema computation I have modified this behaviour to set the alias of the 
new operator to that of its predecessor. The logical side of the patch mimics 
the cogroup behavior as join syntax closely resembles that of cogroup. 
Currently, this patch doesn't have support for joins other than inner joins. 
The rest of the code has been documented.

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