Given the resoult of a GROUP operation how can I store each nested-bag in a folder named after the group? - apache-pig

Question

I've a relation D:
grunt> DESCRIBE D;
D: {i: int,l: chararray}
on which a GROUP is applied:
grunt> G = group D by i;
grunt> illustrate G;
-------------------------------------
| D | i:int | l:chararray |
-------------------------------------
| | 1 | B |
| | 1 | A |
| | 2 | A |
-------------------------------------
-----------------------------------------------------------------------
| G | group:int | D:bag{:tuple(i:int,l:chararray)} |
-----------------------------------------------------------------------
| | 1 | {(1, B), (1, A)} |
| | 2 | {(2, A)} |
-----------------------------------------------------------------------
How can I store each nested bag G.D in a file named as the corresponding group? I.e. /ouput/1, /output/2
I understand I can't use a store operation in a foreach block. In fact the following doeasn't work:
grunt> foreach G { store D into '/output/' + ((chararray) group) }

Answer 1

MultiStorage() option will work for you. It will be available in piggybank jar. You need to download from this link http://www.java2s.com/Code/Jar/p/Downloadpiggybankjar.htm and set it in your classpath.
Example:
input
1,A
1,B
2,A
PigScript:
REGISTER '/tmp/piggybank.jar';
A = LOAD 'input' USING PigStorage(',') AS (i:int,l:chararray);
B = GROUP A BY i;
STORE B INTO 'output' USING org.apache.pig.piggybank.storage.MultiStorage('output', '0');
Now output folder contains 2 dirs named 1 and 2 where the corresponding group value will be stored inside this folder.
Output:
output$ ls
1 2 _SUCCESS
Reference:
https://pig.apache.org/docs/r0.10.0/api/org/apache/pig/piggybank/storage/MultiStorage.html