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https://issues.apache.org/jira/browse/PIG-282?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Olga Natkovich updated PIG-282:
-------------------------------
Release Note:
This feature allows to specify Hadoop Partitioner for the following operations:
GROUP/COGROUP, CROSS, DISTINCT, JOIN (except 'skewed' join). Partitioner
controls the partitioning of the keys of the intermediate map-outputs. See
http://hadoop.apache.org/common/docs/current/api/org/apache/hadoop/mapred/Partitioner.html
for more details.
To use this feature you can add PARTITION BY clause to the appropriate operator:
A = load 'input_data';
B = group A by $0 PARTITION BY
org.apache.pig.test.utils.SimpleCustomPartitioner parallel 2;
.....
Here is the code for SimpleCustomPartitioner
public class SimpleCustomPartitioner extends Partitioner<PigNullableWritable,
Writable> {
//@Override
public int getPartition(PigNullableWritable key, Writable value, int
numPartitions) {
if(key.getValueAsPigType() instanceof Integer) {
int ret = (((Integer)key.getValueAsPigType()).intValue() %
numPartitions);
return ret;
}
else {
return (key.hashCode()) % numPartitions;
}
}
}
> Custom Partitioner
> ------------------
>
> Key: PIG-282
> URL: https://issues.apache.org/jira/browse/PIG-282
> Project: Pig
> Issue Type: New Feature
> Affects Versions: 0.7.0
> Reporter: Amir Youssefi
> Assignee: Aniket Mokashi
> Priority: Minor
> Fix For: 0.8.0
>
> Attachments: CustomPartitioner.patch, CustomPartitionerFinale.patch,
> CustomPartitionerTest.patch
>
>
> By adding custom partitioner we can give control over which output partition
> a key (/value) goes to. We can add keywords to language e.g.
> PARTITION BY UDF(...)
> or a similar syntax. UDF returns a number between 0 and n-1 where n is number
> of output partitions.
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