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From "Namit Jain (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HIVE-1783) CommonJoinOperator optimize the case of 1:1 join
Date Wed, 17 Nov 2010 17:40:13 GMT

     [ https://issues.apache.org/jira/browse/HIVE-1783?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Namit Jain updated HIVE-1783:
-----------------------------

    Status: Open  (was: Patch Available)

Can you refresh the patch ? HIVE-1642 has been committed, so this is good to go

> 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, HIVE-1783.2.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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