[jira] Commented: (HIVE-1783) CommonJoinOperator optimize the case of 1:1 join

["Namit Jain (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-1783?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12931303#action_12931303 ] 

Namit Jain commented on HIVE-1783:
----------------------------------

+1

running tests

> CommonJoinOperator optimize the case of 1:1 join
> ------------------------------------------------
>
>                 Key: HIVE-1783
>                 URL: https://issues.apache.org/jira/browse/HIVE-1783
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Siying Dong
>            Assignee: Siying Dong
>            Priority: Minor
>         Attachments: HIVE-1783.1.patch
>
>
> CommonJoinOperator.genObject() is expensive. It does a recursive and keeps lots of states because it has to:
> 1. handle null cases for outer joins
> 2. handle the case of duplicated keys from one join party
> We can do a minor optimization to detect a 1:1 join (which is quite common) before calling CommonJoinOperator.genObject() and forward columns in a simple for-loop if we are sure neither of 1 or 2 will happen.

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