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Posted to issues@spark.apache.org by "Hyukjin Kwon (JIRA)" <ji...@apache.org> on 2018/11/09 04:10:00 UTC

[jira] [Resolved] (SPARK-25976) Allow rdd.reduce on empty rdd by returning an Option[T]

     [ https://issues.apache.org/jira/browse/SPARK-25976?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hyukjin Kwon resolved SPARK-25976.
----------------------------------
    Resolution: Won't Fix

> Allow rdd.reduce on empty rdd by returning an Option[T]
> -------------------------------------------------------
>
>                 Key: SPARK-25976
>                 URL: https://issues.apache.org/jira/browse/SPARK-25976
>             Project: Spark
>          Issue Type: Improvement
>          Components: Spark Core
>    Affects Versions: 2.3.2
>            Reporter: Yuval Yaari
>            Priority: Minor
>
> it is sometimes useful to let the user decide what value to return when reducing on an empty rdd.
> currently, if there is no data to reduce an UnsupportedOperationException is thrown. 
> although user can catch that exception, it seems like a "shaky" solution as UnsupportedOperationException might be thrown from a different location.
> Instead, we can overload the reduce method by adding add a new method:
> reduce(f: (T, T) => T, defaultIfEmpty: () => T): T
> the reduce API will not be effected as it will simply call the second reduce method throwing an UnsupportedException as the default value
>  



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