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Posted to dev@hive.apache.org by "Xuefu Zhang (JIRA)" <ji...@apache.org> on 2014/12/05 04:15:13 UTC
[jira] [Commented] (HIVE-5771) Constant propagation optimizer for
Hive
[ https://issues.apache.org/jira/browse/HIVE-5771?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14234992#comment-14234992 ]
Xuefu Zhang commented on HIVE-5771:
-----------------------------------
This optimization might have caused the problem in HIVE-9025.
> 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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