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https://issues.apache.org/jira/browse/HIVE-22913?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17040750#comment-17040750
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Zoltan Haindrich commented on HIVE-22913:
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not sure how much we gain from these simplification calls; possibly worth
considering:
* A: only invoke simplification after the rule
* B: invoke simplification in case it makes a structural change; however in
this case we still need to invoke it after the rule
* C: remove the simplification entirely; and add a new rule(SimplifyRule) which
will only run simplification; put the existing ReduceExpressionRule and the new
SimplifyRule in a RuleCollection
I'll explore A first
> HiveReduceExpressionsWithStatsRule should not invoke simplifcation during end
> of visits
> ---------------------------------------------------------------------------------------
>
> Key: HIVE-22913
> URL: https://issues.apache.org/jira/browse/HIVE-22913
> Project: Hive
> Issue Type: Improvement
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
>
> * doing a simplification is a full visit of the subtree
> * in case the rule makes a structural change; it will invoke simplification
> during exiting the recursion
> https://github.com/apache/hive/blob/5012954396c98c94d0ff64fe3bbdb74e6077f190/ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveReduceExpressionsWithStatsRule.java#L275
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