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Posted to dev@hive.apache.org by "Ashutosh Chauhan (JIRA)" <ji...@apache.org> on 2016/11/17 20:03:58 UTC

[jira] [Created] (HIVE-15234) Semijoin cardinality estimation can be improved

Ashutosh Chauhan created HIVE-15234:
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             Summary: Semijoin cardinality estimation can be improved
                 Key: HIVE-15234
                 URL: https://issues.apache.org/jira/browse/HIVE-15234
             Project: Hive
          Issue Type: Bug
          Components: CBO, Logical Optimizer
    Affects Versions: 2.1.0, 2.0.0
            Reporter: Ashutosh Chauhan
            Assignee: Ashutosh Chauhan


Currently calcite optimization rules rely on (Hive)SemiJoin to represent semi join node, whereas Stats estimate use {{leftSemiJoin}} field of Join to estimate stats. As a result semi-join specific stats calculation logic is never hit since at plan generation time HiveSemiJoin is created and leftSemiJoin field of Join is never set.



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