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From "Aihua Xu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-9228) Problem with subquery using windowing functions
Date Wed, 28 Jan 2015 15:09:35 GMT

    [ https://issues.apache.org/jira/browse/HIVE-9228?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14295254#comment-14295254
] 

Aihua Xu commented on HIVE-9228:
--------------------------------

[~navis] Since you are working on this issue and have much better knowledge on windowing functions
than me, do you want me to assign the issue to you? 

> Problem with subquery using windowing functions
> -----------------------------------------------
>
>                 Key: HIVE-9228
>                 URL: https://issues.apache.org/jira/browse/HIVE-9228
>             Project: Hive
>          Issue Type: Bug
>          Components: PTF-Windowing
>    Affects Versions: 0.13.1
>            Reporter: Aihua Xu
>            Assignee: Aihua Xu
>         Attachments: HIVE-9228.1.patch.txt, HIVE-9228.2.patch.txt, create_table_tab1.sql,
tab1.csv
>
>   Original Estimate: 96h
>  Remaining Estimate: 96h
>
> The following query with window functions failed. The internal query works fine.
> select col1, col2, col3 from (select col1,col2, col3, count(case when col4=1 then 1 end
) over (partition by col1, col2) as col5, row_number() over (partition by col1, col2 order
by col4) as col6 from tab1) t;
> HIVE generates an execution plan with 2 jobs. 
> 1. The first job is to basically calculate window function for col5.  
> 2. The second job is to calculate window function for col6 and output.
> The plan says the first job outputs the columns (col1, col2, col3, col4) to a tmp file
since only these columns are used in later stage. While, the PTF operator for the first job
outputs (_wcol0, col1, col2, col3, col4) with _wcol0 as the result of the window function
even it's not used. 
> In the second job, the map operator still reads the 4 columns (col1, col2, col3, col4)
from the temp file using the plan. That causes the exception.



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