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From "Ashutosh Chauhan (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-15234) Semijoin cardinality estimation can be improved
Date Fri, 18 Nov 2016 23:05:58 GMT

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

Ashutosh Chauhan updated HIVE-15234:
------------------------------------
    Attachment: HIVE-15234.patch

> 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
>         Attachments: 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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