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From "pengcheng xiong (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-7506) MetadataUpdater: provide a mechanism to edit the statistics of a column in a table (or a partition of a table)
Date Tue, 05 Aug 2014 20:51:13 GMT

    [ https://issues.apache.org/jira/browse/HIVE-7506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14086729#comment-14086729
] 

pengcheng xiong commented on HIVE-7506:
---------------------------------------

Hello Hive QA,

    I have carefully studied the errors that you sent. I think none of them is related to
the patch that I uploaded. Could you please just ignore them? Thanks!

Best

> MetadataUpdater: provide a mechanism to edit the statistics of a column in a table (or
a partition of a table)
> --------------------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-7506
>                 URL: https://issues.apache.org/jira/browse/HIVE-7506
>             Project: Hive
>          Issue Type: New Feature
>          Components: Database/Schema
>            Reporter: pengcheng xiong
>            Assignee: pengcheng xiong
>            Priority: Minor
>         Attachments: HIVE-7506.1.patch, HIVE-7506.3.patch, HIVE-7506.4.patch, HIVE-7506.patch
>
>   Original Estimate: 252h
>  Remaining Estimate: 252h
>
> Two motivations:
> (1) Cost-based Optimizer (CBO) depends heavily on the statistics of a column in a table
(or a partition of a table). If we would like to test whether CBO chooses the best plan under
different statistics, it would be time consuming if we load the whole table and create the
statistics from ground up.
> (2) As database runs,  the statistics of a column in a table (or a partition of a table)
may change. We need a way or a mechanism to synchronize. 
> We propose the following command to achieve that:
> ALTER TABLE table_name PARTITION partition_spec [COLUMN col_name] UPDATE STATISTICS col_statistics
[COMMENT col_comment]



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