[jira] [Created] (PIG-4583) Allow UDFs to return multiple values (not inside a Bag or a Tuple)

["Carlos Balduz (JIRA)" <ji...@apache.org>]

Carlos Balduz created PIG-4583:
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             Summary: Allow UDFs to return multiple values (not inside a Bag or a Tuple)
                 Key: PIG-4583
                 URL: https://issues.apache.org/jira/browse/PIG-4583
             Project: Pig
          Issue Type: Improvement
    Affects Versions: 0.14.0
            Reporter: Carlos Balduz


When writing a UDF, you are forced to return only one value, or multiple values but inside a Tuple or a Bag. Although this may not seem a big problem, when using Pig in production and performing multiple JOINs, GROUP BYs and any operations that make your schema more and more complicated, it would be nice to create a UDF to reduce the size of your schema, for example:
```
    rel1  = load 'a' using PigStorage(';', '-schema');
    rel2  = load 'b' using PigStorage(';', '-schema');

    joined = join rel1 by id_whatever, rel2 by id_whatever;

    ... perform operations

    another_rel = load 'c' using PigStorage('.'.'-schema');
    final_rel = join another_rel by id_whatever, joined by id_whatever;
```
Will have an schema like:
```
    describe final_rel;
    rel1::joined::id_whatever, rel1:joined::field_1, ......
```

When you have scripts with hundreds or thousands of lines of code, you end up having more foreachs to rename fields than with actual code. Therefore, I wrote a UDF to handle this so I wouldn't have to write a foreach to rename 100 fields one by one.

However, due to Pig's limitation of returning only one value, I must place my return values inside a Tupe or a Bag, flatten it, and have another `something::` for each of the fields.

Can we remove this limitation? And if it is done, perhaps upload the UDF I wrote... I think it is a VERY useful function for production environments and large scripts.



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