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From "Ashutosh Chauhan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5771) Constant propagation optimizer for Hive
Date Sat, 31 May 2014 20:27:02 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5771?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14014799#comment-14014799
] 

Ashutosh Chauhan commented on HIVE-5771:
----------------------------------------

[~tedxu] I think for now we can disable this optimization if hive.optimize.index.filter is
on. We can take that on in a follow on jira. Are there any other bugs you are running into?
Also, you may want to checkout HIVE-4867 changes getting made there may be useful for this
patch.

> 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: HIVE-5771.1.patch, HIVE-5771.10.patch, HIVE-5771.2.patch, HIVE-5771.3.patch,
HIVE-5771.4.patch, HIVE-5771.5.patch, HIVE-5771.6.patch, HIVE-5771.7.patch, HIVE-5771.8.patch,
HIVE-5771.9.patch, HIVE-5771.patch, HIVE-5771.patch.javaonly
>
>
> 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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