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From "Lars Francke (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 Wed, 06 Aug 2014 00:23:12 GMT

    [ https://issues.apache.org/jira/browse/HIVE-7506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14087017#comment-14087017
] 

Lars Francke commented on HIVE-7506:
------------------------------------

Pengcheng, thanks for addressing my questions.

{quote}So, I will always post in https://reviews.apache.org/r/24289/ in the future?{quote}

At least for this issue, yes. That way it's easy for us to compare different versions of your
patch and only review those parts again that have changed.

{quote}Tab policy as spaces only, Tab size -> 2
Is that enough?{quote}

That sounds correct but unfortunately I don't use Eclipse so I can't help there.

{quote}I have no idea about the authorization part either. I do not think I have made any
changes on that.{quote}

As mentioned I don't know either but I'm sure we'll find someone here who can help (or at
your end at Hortonworks). I'm sure that we'll want this to be secured somehow.

Primitives/Objects: Thanks for the explanation, I'll take a look tomorrow.

I have taken another quick look at the patch. It looks much better but unfortunately still
contains a lot of "formal" errors but I'm sure we'll get through them :) I'll try to continue
the review tomorrow if no one else has gotten to it before then.

> 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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