hadoop-hive-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Zheng Shao (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HIVE-582) "SELECT count(1) as cnt from src x" not working for column pruning
Date Mon, 29 Jun 2009 19:00:47 GMT

     [ https://issues.apache.org/jira/browse/HIVE-582?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Zheng Shao updated HIVE-582:
----------------------------

    Status: Patch Available  (was: Open)

> "SELECT count(1) as cnt from src x" not working for column pruning
> ------------------------------------------------------------------
>
>                 Key: HIVE-582
>                 URL: https://issues.apache.org/jira/browse/HIVE-582
>             Project: Hadoop Hive
>          Issue Type: Bug
>            Reporter: Yongqiang He
>            Assignee: Yongqiang He
>         Attachments: hive-582-2009-06-25.patch
>
>
> The query "SELECT count(1) as cnt from src x"  has some problems, even though nullgroup*.q
passed in tests. 
> Will check and solve it in this jira.
> A wrong plan sometimes can be generated due to some unknow factor:
> Wrong plan:
> {noformat}
> STAGE PLANS:
>   Stage: Stage-1
>     Map Reduce
>       Alias -> Map Operator Tree:
>         x 
>             Select Operator
>               Reduce Output Operator
>                 sort order: 
>                 tag: -1
>       Reduce Operator Tree:
>         Group By Operator
>           aggregations:
>                 expr: count(VALUE._col0)
>           mode: complete
>           Select Operator
>             expressions:
>                   expr: _col0
>                   type: bigint
>             File Output Operator
>               compressed: false
>               GlobalTableId: 0
>               table:
>                   input format: org.apache.hadoop.mapred.TextInputFormat
>                   output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
>   Stage: Stage-0
>     Fetch Operator
>       limit: -1
> {noformat}
> Without unknow factor, correct plan can be generated:
> {noformat}
> STAGE PLANS:
>   Stage: Stage-1
>     Map Reduce
>       Alias -> Map Operator Tree:
>         x 
>             Select Operator
>               Group By Operator
>                 aggregations:
>                       expr: count(1)
>                 mode: hash
>                 Reduce Output Operator
>                   sort order: 
>                   tag: -1
>                   value expressions:
>                         expr: _col0
>                         type: bigint
>       Reduce Operator Tree:
>         Group By Operator
>           aggregations:
>                 expr: count(VALUE._col0)
>           mode: mergepartial
>           Select Operator
>             expressions:
>                   expr: _col0
>                   type: bigint
>             File Output Operator
>               compressed: false
>               GlobalTableId: 0
>               table:
>                   input format: org.apache.hadoop.mapred.TextInputFormat
>                   output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
> {noformat}

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message