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Posted to issues@hive.apache.org by "Zoltan Haindrich (JIRA)" <ji...@apache.org> on 2019/03/04 17:07:00 UTC
[jira] [Updated] (HIVE-21152) Rewrite if expression to case and
recognize simple case as an if
[ https://issues.apache.org/jira/browse/HIVE-21152?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Zoltan Haindrich updated HIVE-21152:
------------------------------------
Attachment: HIVE-21152.04.patch
> Rewrite if expression to case and recognize simple case as an if
> ----------------------------------------------------------------
>
> Key: HIVE-21152
> URL: https://issues.apache.org/jira/browse/HIVE-21152
> Project: Hive
> Issue Type: Improvement
> Components: CBO
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
> Attachments: HIVE-21152.01.patch, HIVE-21152.02.patch, HIVE-21152.03.patch, HIVE-21152.04.patch
>
>
> * {{IF}} is not part of the sql standard; however given its special form its simpler - and currently in Hive it also has vectorized support
> * people writing standard sql may write: {{CASE WHEN member=1 THEN attr+1 else attr+2 END}} which is essentially an if.
> The idea is to rewrite IFs to CASEs for the cbo; and recognize simple "CASE"-s as IFs to get vectorization on them if possible
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