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Date: Thu, 29 Nov 2007 00:01:06 -0800 (PST)
From: "Edward Yoon (JIRA)" <jira@apache.org>
To: hadoop-dev@lucene.apache.org
Subject: [jira] Updated: (HADOOP-2021) Sort Join Implementation
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     [ https://issues.apache.org/jira/browse/HADOOP-2021?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Edward Yoon updated HADOOP-2021:
--------------------------------

    Attachment: patch.txt

> Sort Join Implementation
> ------------------------
>
>                 Key: HADOOP-2021
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2021
>             Project: Hadoop
>          Issue Type: Sub-task
>          Components: contrib/hbase
>    Affects Versions: 0.14.1
>         Environment: all environments  
>            Reporter: Edward Yoon
>            Assignee: Edward Yoon
>            Priority: Minor
>             Fix For: 0.16.0
>
>         Attachments: 2021_v01.patch, 2021_v02.txt, patch.txt
>
>
> If we don't have an index for a domain in the join, we can still improve on the nested-loop join using sort join.
> {code}
> R1 = table('movieLog_table');
> R2 = table('stockCompany_info');
> result = R1.join(R1.studioName = R2.corporation) and R2;
> {code}
> ----
> {code}
> r1
>        a     b    c
> ======================
> row1   a1    b1   c1
> row2   a2    b2   c2
> row3   a1    b3   c3
> r2
>        e     f
> ==================
> row1   e1    a1
> row2   e2    f2
> row3   e3    f3
> row4   e4    a1
> row5   e5    a2
> r1 = table('r1');
> r2 = table('r2');
> r3 = r1.join(r1.a = r2.f) and r2;
> ---------------------------------------------
> temp table T : Sorted set by "f"
>     row       e     f
> ===========================
> a1  row:row1  e1    a1
>     row:row4  e4    
> a2  row:row5  e5    a2
> f2  row:row2  e2    f2
> f3  row:row3  e3    f3
> ---------------------------------------------
> r3
>            r1.row   a    b    c   r2.row    e   f  
> ===================================================
> row1.row1  row1     a1   b1   c1  row1      e1  a1
> row1.row4  row1     a1   b1   c1  row4      e4  a1
> row2.row5  row2     a2   b2   c2  row5      e5  a2
> row3.row1  row3     a1   b3   c3  row1      e1  a1
> row3.row4  row3     a1   b3   c3  row4      e4  a1
> {code}

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