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https://issues.apache.org/jira/browse/HIVE-5771?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13824834#comment-13824834
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Ted Xu commented on HIVE-5771:
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Hi Eric,
Thank you for your reviewing. I already updated the diff file according to your
suggestions.
With regard to timestamp literal and cast constants, this optimizer will fold
them like other primitive types. I tested timestamp and date, it look good to
me. I'm sorry I haven't got chance to merge the tests into HIVE-5771.1.patch. I
will add them later.
> 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.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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