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Date: Mon, 1 Jun 2015 18:45:21 +0000 (UTC)
From: "Sean Hsuan-Yi Chu (JIRA)" <jira@apache.org>
To: dev@drill.apache.org
Message-ID: <JIRA.12830589.1431931075000.85139.1433184320966@Atlassian.JIRA>
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 <JIRA.12830589.1431931075749@arcas>
Subject: [jira] [Resolved] (DRILL-3130) Project can be pushed below union
 all / union to improve performance
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     [ https://issues.apache.org/jira/browse/DRILL-3130?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sean Hsuan-Yi Chu resolved DRILL-3130.
--------------------------------------
          Resolution: Fixed
       Fix Version/s: 1.1.0
    Target Version/s:   (was: Future)

> Project can be pushed below union all / union to improve performance
> --------------------------------------------------------------------
>
>                 Key: DRILL-3130
>                 URL: https://issues.apache.org/jira/browse/DRILL-3130
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Query Planning & Optimization
>            Reporter: Sean Hsuan-Yi Chu
>            Assignee: Sean Hsuan-Yi Chu
>             Fix For: 1.1.0
>
>
> A query such as 
> {code}
> Select a from 
> (select a, b, c, ..., union all select a, b, c, ...)
> {code}
> will perform Union-All over all the specified columns on the two sides, despite the fact that only one column is asked for at the end. Ideally, we should perform ProjectPushDown rule for Union & Union-All to avoid them to generate results which will be discarded at the end.


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