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From "Namit Jain (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-1950) Block merge for RCFile
Date Fri, 04 Feb 2011 02:40:23 GMT

    [ https://issues.apache.org/jira/browse/HIVE-1950?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12990434#comment-12990434
] 

Namit Jain commented on HIVE-1950:
----------------------------------

I will take a look - 1 minor comment.
Can you add some negative tests:

1. merge_files should fail if there is a index on the table/partition.
2. merge_files should fail if the table is partitioned, but the user did not specify the partition.


Going forward, we should support merge even if the partition is not fully specified.

alter table srcpart partition (ds='1') merge_files;

should merge ds=1/hr=1 and ds=1/hr=2 as a follow-up.
But for now, they should throw an error

> Block merge for RCFile
> ----------------------
>
>                 Key: HIVE-1950
>                 URL: https://issues.apache.org/jira/browse/HIVE-1950
>             Project: Hive
>          Issue Type: New Feature
>            Reporter: He Yongqiang
>            Assignee: He Yongqiang
>         Attachments: HIVE-1950.1.patch
>
>
> In our env, there are a lot of small files inside one partition/table. In order to reduce
the namenode load, we have one dedicated housekeeping job running to merge these file. Right
now the merge is an 'insert overwrite' in hive, and requires decompress the data and compress
it. This jira is to add a command in Hive to do the merge without decompress and recompress
the data.
> Something like "alter table tbl_name [partition ()] merge files". In this jira the new
command will only support RCFile, since there need some new APIs to the fileformat.

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