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From "Mostafa Mokhtar (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-9392) Hive : JoinStatsRule overwrites the column statistics in HashMap because column names have duplicate fqColumnName
Date Thu, 15 Jan 2015 20:37:34 GMT
Mostafa Mokhtar created HIVE-9392:
-------------------------------------

             Summary: Hive : JoinStatsRule overwrites the column statistics in HashMap because
column names have duplicate fqColumnName
                 Key: HIVE-9392
                 URL: https://issues.apache.org/jira/browse/HIVE-9392
             Project: Hive
          Issue Type: Bug
          Components: Physical Optimizer
    Affects Versions: 0.14.0
            Reporter: Mostafa Mokhtar
            Assignee: Prasanth Jayachandran
            Priority: Critical
             Fix For: 0.15.0


In JoinStatsRule.process the join column statistics are stored in HashMap  joinedColStats,
the key used which is the ColStatistics.fqColName is duplicated between join column in the
same vertex, as a result distinctVals ends up having duplicated values which negatively affects
the join cardinality estimation.

The duplicate keys are usually named KEY.reducesinkkey0.



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