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https://issues.apache.org/jira/browse/HIVE-20108?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sahil Takiar reassigned HIVE-20108:
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> 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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