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Posted to issues@hive.apache.org by "Vineet Garg (JIRA)" <ji...@apache.org> on 2017/09/09 00:32:00 UTC

[jira] [Updated] (HIVE-17493) Improve PKFK cardinality estimation in Physical planning

     [ https://issues.apache.org/jira/browse/HIVE-17493?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Vineet Garg updated HIVE-17493:
-------------------------------
    Status: Patch Available  (was: Open)

> Improve PKFK cardinality estimation in Physical planning
> --------------------------------------------------------
>
>                 Key: HIVE-17493
>                 URL: https://issues.apache.org/jira/browse/HIVE-17493
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Planning
>            Reporter: Vineet Garg
>            Assignee: Vineet Garg
>         Attachments: HIVE-17493.1.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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