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From "Vineet Garg (JIRA)" <>
Subject [jira] [Updated] (HIVE-17493) Improve PKFK cardinality estimation in Physical planning
Date Wed, 13 Sep 2017 22:23:00 GMT


Vineet Garg updated HIVE-17493:
    Attachment: HIVE-17493.3.patch

> Improve PKFK cardinality estimation in Physical planning
> --------------------------------------------------------
>                 Key: HIVE-17493
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Planning
>            Reporter: Vineet Garg
>            Assignee: Vineet Garg
>         Attachments: HIVE-17493.1.patch, HIVE-17493.2.patch, HIVE-17493.3.patch
> Cardinality estimation of a join, after PK-FK relation has been ascertained, could be
improved if parent of the join operator is LEFT outer or RIGHT outer join.
> Currently estimation is done by estimating reduction of rows occurred on PK side, then
multiplying the reduction to FK side row count. This estimation of reduction currently doesn't
distinguish b/w INNER or OUTER joins. This could be improved to handle outer joins better.
> TPC-DS query45 is impacted by this.

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