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From "Eric Hanson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5771) Constant propagation optimizer for Hive
Date Thu, 14 Nov 2013 22:09:21 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5771?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13823000#comment-13823000
] 

Eric Hanson commented on HIVE-5771:
-----------------------------------

Does this do constant folding before the vectorization process? If it can do that, then more
queries will vectorize. 

Please put up a ReviewBoard entry for your patch to make it easier to review.

Thanks,
Eric

> Constant propagation optimizer for Hive
> ---------------------------------------
>
>                 Key: HIVE-5771
>                 URL: https://issues.apache.org/jira/browse/HIVE-5771
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: Ted Xu
>            Assignee: Ted Xu
>         Attachments: constprog_default_true.patch
>
>
> Currently there is no constant folding/propagation optimizer, all expressions are evaluated
at runtime. 
> HIVE-2470 did a great job on evaluating constants on UDF initializing phase, however,
it is still a runtime evaluation and it doesn't propagate constants from a subquery to outside.
> It may reduce I/O and accelerate process if we introduce such an optimizer.



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