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From "Namit Jain (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-556) let hive support theta join
Date Fri, 12 Jun 2009 06:14:07 GMT

    [ https://issues.apache.org/jira/browse/HIVE-556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12718733#action_12718733
] 

Namit Jain commented on HIVE-556:
---------------------------------

I think what Ashish meant was that if one table is small (aux table with 10 records), you
can do a cartesian product with that table via map-join which wont be very expensive and then
apply your join condition in the form of a filter. Still, no sorting is required - so it should
not be all that bad.

> let hive support theta join
> ---------------------------
>
>                 Key: HIVE-556
>                 URL: https://issues.apache.org/jira/browse/HIVE-556
>             Project: Hadoop Hive
>          Issue Type: New Feature
>    Affects Versions: 0.4.0
>            Reporter: Min Zhou
>             Fix For: 0.4.0
>
>
> Right now , hive only support equal joins .  Sometimes it's not enough, we must consider
implementing theta joins like
> {code:sql}
> SELECT
>   a.subid, a.id, t.url
> FROM
>   tbl t JOIN aux_tbl a ON t.url rlike a.url_pattern
> WHERE
>   t.dt='20090609'
>   AND a.dt='20090609';
> {code}
> any condition expression following 'ON' is  appropriate.

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