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From "Selina Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-6492) limit partition number involved in a table scan
Date Sat, 01 Mar 2014 03:36:19 GMT

    [ https://issues.apache.org/jira/browse/HIVE-6492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13916765#comment-13916765
] 

Selina Zhang commented on HIVE-6492:
------------------------------------

The original patch actually has two tasks included:
1. limit the partition number when a table scan happens:
2. a hack to identify the query from Tableau and do special handling for it.
As we discussed, the second task is just a hack and probably it is not helpful if commit it
to trunk. So I created a new patch which only contains the first task. 
The reason of introducing this configure variable is we want to limit the number of partitions
when do table scan. As for metadata only query, since HIVE-1003 has the optimization on this
type of query , the table scan is not a problem any more. 



> limit partition number involved in a table scan
> -----------------------------------------------
>
>                 Key: HIVE-6492
>                 URL: https://issues.apache.org/jira/browse/HIVE-6492
>             Project: Hive
>          Issue Type: New Feature
>          Components: Query Processor
>    Affects Versions: 0.12.0
>            Reporter: Selina Zhang
>             Fix For: 0.13.0
>
>         Attachments: HIVE-6492.1.patch.txt, HIVE-6492.2.patch.txt
>
>   Original Estimate: 24h
>  Remaining Estimate: 24h
>
> To protect the cluster, a new configure variable "hive.limit.query.max.table.partition"
is added to hive configuration to
> limit the table partitions involved in a table scan. 
> The default value will be set to -1 which means there is no limit by default. 
> This variable will not affect "metadata only" query.



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