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https://issues.apache.org/jira/browse/SPARK-4367?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Cheng Hao updated SPARK-4367:
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Summary: 2 Phase-shuffle to optimize the DISTINCT aggregation (was:
Process the "distinct" value before shuffling for aggregation)
> 2 Phase-shuffle to optimize the DISTINCT aggregation
> ----------------------------------------------------
>
> Key: SPARK-4367
> URL: https://issues.apache.org/jira/browse/SPARK-4367
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Reporter: Cheng Hao
>
> Most of aggregate function(e.g average) with "distinct" value will requires
> all of the records in the same group to be shuffled into a single node,
> however, as part of the optimization, those records can be partially
> aggregated before shuffling, that probably reduces the overhead of shuffling
> significantly.
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