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https://issues.apache.org/jira/browse/HIVE-5888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13921745#comment-13921745
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Navis commented on HIVE-5888:
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Skew join in current implementation is infamous for not reducing total
execution time. For checking skewness, all values should be shuffled first,
which means all damages are already done in that state. Skewed keys are store
in reducer and following MR job processes them.
There are other options like list bucketing(HIVE-3073), or explicit skew
join(HIVE-3286), and the former is available in hive-0.11.0.
> group by after join operation product no result when hive.optimize.skewjoin
> = true
> ------------------------------------------------------------------------------------
>
> Key: HIVE-5888
> URL: https://issues.apache.org/jira/browse/HIVE-5888
> Project: Hive
> Issue Type: Bug
> Affects Versions: 0.11.0, 0.12.0
> Reporter: cyril liao
> Priority: Critical
>
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