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From "Raghotham Murthy (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-591) create new type of join ( 1 row for a given key from multiple tables)
Date Fri, 07 Aug 2009 09:10:14 GMT

    [ https://issues.apache.org/jira/browse/HIVE-591?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12740457#action_12740457
] 

Raghotham Murthy commented on HIVE-591:
---------------------------------------

@Adam, i guess the plan is to support join on multiple keys. Also, the operator is not ternary,
it is n-ary - just that we used only 3 tables in the examples.

> create new type of join ( 1 row for a given key from multiple tables)
> ---------------------------------------------------------------------
>
>                 Key: HIVE-591
>                 URL: https://issues.apache.org/jira/browse/HIVE-591
>             Project: Hadoop Hive
>          Issue Type: New Feature
>          Components: Query Processor
>            Reporter: Namit Jain
>
> It will be useful to support a new type of join:
> say:
> select .. from JOIN TABLES (A,B,C) WITH KEYS (A.key, B.key, C.key) where ....
> The semantics are that for a given key only 1 row is created - nulls are present for
the the tables which do not contain a row for that key.
> There is no limit on the number of tables, the number of keys should be the same as the
number of tables.

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