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From "Prasad Chakka (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-918) Allow partition-wise file format
Date Tue, 10 Nov 2009 01:11:32 GMT

    [ https://issues.apache.org/jira/browse/HIVE-918?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12775233#action_12775233
] 

Prasad Chakka commented on HIVE-918:
------------------------------------

Regarding metadata,
1) Every partition has its own Storage Descriptor object which contains information about
file descriptors, serdes and other storage related information that a table can have. There
is no need to add more metadata to partition.

2) If we have 1) what is the need for this? Can we not get all the different file formats
that a table has by querying the storage descriptors of all partitions of a table?

The plan for allowing metadata evolution is that the 'alter table ...' cmd changes metadata
for a table but not for existing partitions. All new partitions inherit the new metadata of
the table. Hive QL should figure out the list of partitions that a query touches on using
just the latest table metadata and then fetch the partition metadata for any further stuff.
Are we changing this to something different, if so what?



> Allow partition-wise  file format
> ---------------------------------
>
>                 Key: HIVE-918
>                 URL: https://issues.apache.org/jira/browse/HIVE-918
>             Project: Hadoop Hive
>          Issue Type: Improvement
>            Reporter: He Yongqiang
>            Assignee: He Yongqiang
>
> Right now all partitions in a hive table share the same file format. We should allow
partition wise file format. 

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