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Posted to issues@spark.apache.org by "Hyukjin Kwon (JIRA)" <ji...@apache.org> on 2019/05/21 04:22:04 UTC
[jira] [Updated] (SPARK-17416) Add Dataset.groupByKey overload that
takes a value selector function
[ https://issues.apache.org/jira/browse/SPARK-17416?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Hyukjin Kwon updated SPARK-17416:
---------------------------------
Labels: bulk-closed (was: )
> Add Dataset.groupByKey overload that takes a value selector function
> --------------------------------------------------------------------
>
> Key: SPARK-17416
> URL: https://issues.apache.org/jira/browse/SPARK-17416
> Project: Spark
> Issue Type: New Feature
> Reporter: Daniel Shields
> Priority: Major
> Labels: bulk-closed
>
> I propose that the following overload be added to Dataset[T]:
> def groupByKey[K, V](keyFunc: T => K, valueFunc: T => V)(implicit arg0: Encoder[K], arg1: Encoder[V])
> This would simplify a number of use cases. For example, consider the following classic MapReduce query:
> rdd.flatMap(f).reduceByKey(g) // where f returns a list of tuples
> An idiomatic way to write this with Spark 2.0 would be:
> dataset.flatMap(f).groupByKey(_._1, _._2).reduceGroups(g)
> Without the groupByKey overload suggested above, this must be written as:
> dataset.flatMap(f).groupByKey(_._1).reduceGroups((a, b) => g(a._2, b._2))
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