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From "Min Zhou (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-556) let hive support theta join
Date Mon, 15 Jun 2009 11:11:07 GMT

    [ https://issues.apache.org/jira/browse/HIVE-556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12719518#action_12719518
] 

Min Zhou commented on HIVE-556:
-------------------------------

I didn't see any filter there,  hive will put all fields of my small table into HTree.

{noformat}
hive>explain select /*+ MAPJOIN(a) */ a.url_pattern, w.url from application a join web_log
w where w.logdate='20090611' and w.url rlike a.url_pattern and a.dt='20090609';

Common Join Operator
              condition map:
                   Inner Join 0 to 1
              condition expressions:
                0 {bussiness_id} {subclass_id} {class_id} {note} {name} {url_pattern} {dt}
                1....
{noformat}

We only put a.url_pattern into a HashMap in our raw map-reduce implemenation.

> 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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