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From "Matt McCline (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-11406) Vectorization: StringExpr::compare() == 0 is bad for performance
Date Tue, 04 Aug 2015 18:10:04 GMT

    [ https://issues.apache.org/jira/browse/HIVE-11406?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14654069#comment-14654069
] 

Matt McCline commented on HIVE-11406:
-------------------------------------

Committed to master.

> Vectorization: StringExpr::compare() == 0 is bad for performance
> ----------------------------------------------------------------
>
>                 Key: HIVE-11406
>                 URL: https://issues.apache.org/jira/browse/HIVE-11406
>             Project: Hive
>          Issue Type: Bug
>          Components: Vectorization
>    Affects Versions: 1.3.0, 2.0.0
>            Reporter: Gopal V
>            Assignee: Matt McCline
>         Attachments: HIVE-11406.01.patch
>
>
> {{StringExpr::compare() == 0}} is forced to evaluate the whole memory comparison loop
for differing lengths of strings, though there is no possibility they will ever be equal.
> Add a {{StringExpr::equals}} which can be a smaller and tighter loop.



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