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From "Sahil Takiar (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (HIVE-20108) Investigate alternatives to groupByKey
Date Fri, 06 Jul 2018 20:56:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-20108?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sahil Takiar reassigned HIVE-20108:
-----------------------------------


> Investigate alternatives to groupByKey
> --------------------------------------
>
>                 Key: HIVE-20108
>                 URL: https://issues.apache.org/jira/browse/HIVE-20108
>             Project: Hive
>          Issue Type: Improvement
>          Components: Spark
>            Reporter: Sahil Takiar
>            Assignee: Sahil Takiar
>            Priority: Major
>
> We use {{groupByKey}} for aggregations (or if {{hive.spark.use.groupby.shuffle}} is false
we use {{repartitionAndSortWithinPartitions}}).
> {{groupByKey}} has its drawbacks because it can't spill records within a single key group.
It also seems to be doing some unnecessary work in Spark's {{Aggregator}} (not positive about
this part).
> {{repartitionAndSortWithinPartitions}} is better, but the sorting within partitions isn't
necessary for aggregations.



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