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https://issues.apache.org/jira/browse/HIVE-17572?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrew Sherman reassigned HIVE-17572:
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Assignee: (was: Andrew Sherman)
> Warnings from SparkCrossProductCheck for MapJoins are confusing
> ---------------------------------------------------------------
>
> Key: HIVE-17572
> URL: https://issues.apache.org/jira/browse/HIVE-17572
> Project: Hive
> Issue Type: Improvement
> Components: Spark
> Reporter: Sahil Takiar
> Priority: Major
>
> When the {{SparkCrossProductCheck}} detects a cross-product in a map-join, it
> prints out a confusing warning - e.g. {{Map Join MAPJOIN\[9\]\[bigTable=?\]
> in task 'Stage-1:MAPRED' is a cross product}}
> I see a few ways this can be imrpoved:
> * {{bigTable}} should actually specify the big table
> * I'm not sure why the stage id is printed instead of the work id, when a
> cross product is detected in a shuffle join the work id is shown (e.g.
> {{Warning: Shuffle Join JOIN\[13\]\[tables = \[$hdt$_1, $hdt$_2, $hdt$_0\]\]
> in Work 'Reducer 3' is a cross product}})
> * It shouldn't say {{MAPRED}} that can be confusing to users
> * The {{MAPJOIN}} id doesn't need to be printed, it doesn't have any meaning
> to the user and the value just keeps on going up and up the longer a session
> lives
> On a somewhat related note, could we just stick this warning in the explain
> plan? Otherwise users may not even notice it
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