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Posted to issues@hive.apache.org by "Owen O'Malley (JIRA)" <ji...@apache.org> on 2017/07/26 00:03:06 UTC

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

     [ https://issues.apache.org/jira/browse/HIVE-15234?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Owen O'Malley closed HIVE-15234.
--------------------------------

> 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: 2.0.0, 2.1.0
>            Reporter: Ashutosh Chauhan
>            Assignee: Ashutosh Chauhan
>             Fix For: 2.2.0
>
>         Attachments: HIVE-15234.1.patch, HIVE-15234.2.patch, HIVE-15234.patch
>
>
> 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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