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Date: Mon, 9 Jun 2014 06:49:32 +0000 (UTC)
From: "Jacques Nadeau (JIRA)" <jira@apache.org>
To: issues@drill.incubator.apache.org
Message-ID: <JIRA.12712384.1399316146591.92612.1402296572483@arcas>
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Subject: [jira] [Updated] (DRILL-636) Push Limit operator past project, left
 outer join, union all operator and down into scan operator
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     [ https://issues.apache.org/jira/browse/DRILL-636?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jacques Nadeau updated DRILL-636:
---------------------------------

    Component/s: Query Planning & Optimization
       Assignee: Aman Sinha

> Push Limit operator past project, left outer join, union all operator and down into scan operator 
> --------------------------------------------------------------------------------------------------
>
>                 Key: DRILL-636
>                 URL: https://issues.apache.org/jira/browse/DRILL-636
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Query Planning & Optimization
>            Reporter: Jinfeng Ni
>            Assignee: Aman Sinha
>
> When we have a limit operator on top of project, left outer join, union all operator, we should push the limit operator, until the limit is put into scan operator. Doing so, it will reduce the amount of data scanned by the scan operator.
> For instance,
> Select COL1, COL2 FROM T1 LIMIT 5;
> LIMIT (5)
>  \
> PROJECT (COL1, COL2)
>  \
> SCAN (T1).
> We need push limit past project, down into scan.
> Similar applies to left outer join, or union all.


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