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From "Eric Hanson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5771) Constant propagation optimizer for Hive
Date Fri, 10 Jan 2014 00:32:51 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5771?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13867338#comment-13867338
] 

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

For vectorization_div0, there is the following diff here: http://bigtop01.cloudera.org:8080/job/PreCommit-HIVE-Build/843/testReport/org.apache.hadoop.hive.cli/TestCliDriver/testCliDriver_vectorization_div0/

<                   expr: ((cdouble >= -500) and (cdouble < -199))
---
>                   expr: ((cdouble >= (- 500)) and (cdouble < (- 199)))

The difference is that the unary-minus was constant-folded so one blank is missing. This is
good and not a problem. The query still vectorizes. The vectorization code has a special-purpose
constant folder in it now to do this. Your code will make that unnecessary.  You can safely
regenerate the .q.out file for this test.

> 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-5771.2.patch, HIVE-5771.3.patch, HIVE-5771.4.patch,
HIVE-5771.5.patch, HIVE-5771.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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