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https://issues.apache.org/jira/browse/HIVE-5771?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14075542#comment-14075542
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Lefty Leverenz commented on HIVE-5771:
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This adds configuration parameter *hive.optimize.constant.propagation* so it
needs to be documented in the wiki for the 0.14.0 release.
* [Configuration Properties |
https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties]
Questions: Should general concepts about the constant propagation optimizer be
documented, or is it sufficient to have the
*hive.optimize.constant.propagation* doc point back to this JIRA ticket? If
additional doc is needed, should it go in the Vectorization design doc or
elsewhere?
* [Design Doc: Vectorized Query Execution |
https://cwiki.apache.org/confluence/display/Hive/Vectorized+Query+Execution]
> 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
> Labels: TODOC14
> Fix For: 0.14.0
>
> Attachments: HIVE-5771.1.patch, HIVE-5771.10.patch,
> HIVE-5771.11.patch, HIVE-5771.12.patch, HIVE-5771.14.patch,
> HIVE-5771.16.patch, HIVE-5771.17.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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