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From "Sergey Shelukhin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-12393) Simplify ColumnPruner when CBO optimizes the query
Date Thu, 19 Nov 2015 23:14:10 GMT

    [ https://issues.apache.org/jira/browse/HIVE-12393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15014703#comment-15014703
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Sergey Shelukhin commented on HIVE-12393:
-----------------------------------------

Is it a big perf gain?

> Simplify ColumnPruner when CBO optimizes the query
> --------------------------------------------------
>
>                 Key: HIVE-12393
>                 URL: https://issues.apache.org/jira/browse/HIVE-12393
>             Project: Hive
>          Issue Type: Bug
>          Components: Logical Optimizer
>    Affects Versions: 2.0.0
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>
> The plan for any given query optimized by CBO will always contain a Project operator
on top of the TS that prunes that columns that are not needed.
> Thus, there is no need for Hive optimizer to traverse the whole plan to check which columns
can be pruned. In fact, Hive ColumnPruner optimizer only needs to match TS operators when
CBO optimized the plan.



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