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From "Hari Sankar Sivarama Subramaniyan (JIRA)" <>
Subject [jira] [Commented] (HIVE-5771) Constant propagation optimizer for Hive
Date Tue, 22 Apr 2014 22:34:15 GMT


Hari Sankar Sivarama Subramaniyan commented on HIVE-5771:

Hi [~tedxu]  I have a  minor comment on the implementation.
Is there a reason for these rules sharing same val.
+    opRules.put(new RuleRegExp("R5", "UNION%"), ConstantPropagateProcFactory
+        .getUnionProc());
+    opRules.put(new RuleRegExp("R5", "RS%"), ConstantPropagateProcFactory
+        .getReduceSinkProc());


> Constant propagation optimizer for Hive
> ---------------------------------------
>                 Key: HIVE-5771
>                 URL:
>             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-5771.6.patch, HIVE-5771.7.patch, HIVE-5771.8.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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