Mailing-List: contact dev-help@hive.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@hive.apache.org
Date: Tue, 7 May 2013 02:35:16 +0000 (UTC)
From: "Lianhui Wang (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Message-ID: <JIRA.12646195.1367840278383.277438.1367894116550@arcas>
In-Reply-To: <JIRA.12646195.1367840278383@arcas>
References: <JIRA.12646195.1367840278383@arcas>
Subject: [jira] [Commented] (HIVE-4506) use one map reduce to join multiple
 small tables
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/HIVE-4506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13650380#comment-13650380 ] 

Lianhui Wang commented on HIVE-4506:
------------------------------------

if these have difference column, HIVE-3784 resolved one big table with multiple small tables.
                
> use one map reduce to join multiple small tables 
> -------------------------------------------------
>
>                 Key: HIVE-4506
>                 URL: https://issues.apache.org/jira/browse/HIVE-4506
>             Project: Hive
>          Issue Type: Wish
>    Affects Versions: 0.10.0
>            Reporter: Fern
>            Priority: Minor
>
> I know we can use map side join for small table.
> by my test, if I use HQL like this
> ------
> select /*+mapjoin(b,c)*/...
> from a
> left join b
> on ...
> left join c
> on ...
> -------
> b and c are both small tables, I expect do the join in one map reduce using map side join. Actually, it would generate two map-reduce jobs by sequence.
> Sorry, currently I am just a user of hive and not dig into the code, so this is what I expect but I have no idea about how to improve now. 

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira