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From "Namit Jain (JIRA)" <>
Subject [jira] Commented: (HIVE-560) column pruning not working with map joins
Date Fri, 19 Jun 2009 22:34:07 GMT


Namit Jain commented on HIVE-560:

Can you explain how is it working ? I was not able to understand it from the code.
Also, there still seems to be a problem: for eg. in join1.q, src1.value is not used but
it is not pruned right away.

> column pruning not working with map joins
> -----------------------------------------
>                 Key: HIVE-560
>                 URL:
>             Project: Hadoop Hive
>          Issue Type: Bug
>          Components: Query Processor
>    Affects Versions: 0.4.0
>            Reporter: Namit Jain
>            Assignee: Yongqiang He
>         Attachments: hive-560-2009-06-19-2.patch, hive-560-2009-06-19-5.patch
> drop table tst1;
> drop table tst2;
> create table tst1(a1 string, a2 string, a3 string, a4 string);
> create table tst2(b1 string, b2 string, b3 string, b4 string);
> explain select /*+ MAPJOIN(a) */ a.a1, a.a2 from tst1 a join tst2 b ON a.a2=b.b2;
> the select is after the join - column pruning is not happening

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