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https://issues.apache.org/jira/browse/HIVE-17139?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16177439#comment-16177439
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Lefty Leverenz commented on HIVE-17139:
---------------------------------------
Review of configuration parameter in patch 13:
{quote}
+
HIVE_VECTORIZATION_CASEWHEN_OPTIMIZATION_ENABLED("hive.vectorized.casewhen.optimization.enable",
true,
+ "This flag should be set to true to enable vectorization optimization
for casewhen expression.The default value is true."),
{quote}
1) Should "casewhen" be "case when" in the description?
2) Please add a space before the description's second sentence.
3) Please use "\n" to split the description into two lines.
> Conditional expressions optimization: skip the expression evaluation if the
> condition is not satisfied for vectorization engine.
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-17139
> URL: https://issues.apache.org/jira/browse/HIVE-17139
> Project: Hive
> Issue Type: Improvement
> Reporter: Ke Jia
> Assignee: Ke Jia
> Attachments: HIVE-17139.10.patch, HIVE-17139.11.patch,
> HIVE-17139.12.patch, HIVE-17139.13.patch, HIVE-17139.13.patch,
> HIVE-17139.1.patch, HIVE-17139.2.patch, HIVE-17139.3.patch,
> HIVE-17139.4.patch, HIVE-17139.5.patch, HIVE-17139.6.patch,
> HIVE-17139.7.patch, HIVE-17139.8.patch, HIVE-17139.9.patch
>
>
> The case when and if statement execution for Hive vectorization is not
> optimal, which all the conditional and else expressions are evaluated for
> current implementation. The optimized approach is to update the selected
> array of batch parameter after the conditional expression is executed. Then
> the else expression will only do the selected rows instead of all.
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