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From "Sushanth Sowmyan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-4847) add rename database functionality
Date Tue, 08 Mar 2016 17:10:40 GMT

    [ https://issues.apache.org/jira/browse/HIVE-4847?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15185267#comment-15185267
] 

Sushanth Sowmyan commented on HIVE-4847:
----------------------------------------

I do not know of any committer's plan to incorporate this or to explicitly block it - I think
this falls in a narrow niche of a feature that would be useful to have, but can prove to be
pretty disruptive in terms of the effects it has on a wider ecosystem tooling. At the very
least, I think that this patch should not go in as-is without some sort of gating mechanism
wherein, by some conf parameter, this feature can be disabled.

I can give one example of a place where I am concerned about this feature, for eg - I know
that external systems like Falcon, that implement replication between one hive warehouse to
another depend on a db name being a primary key, and having that change behind the scene can
be destructive to them. In addition, in the HiveMetaStore, we have event logs that do treat
the db name as a primary key to provide this functionality to Falcon/etc, and this patch does
nothing to change those event log contents. And I stress to add, nor should it modify event
logs directly, since that would violate the expectation a third party tool has. One way to
do this in a seamless manner would be to introduce another notion of a DBKEY (not DB_ID, since
that can be different for each hive warehouse) which will remain unique for a db and not change
when a db is renamed. Once that's done, all hive components that use DBNAME as the identifying
basis would need to be rewritten to work against the DBKEY, and then, renaming DBNAME might
be allowed. This will be a huge change.

Another example I wonder about is with things like ACID transactions - we have a log of tables
needing compaction - I wonder if this change will affect them too. +cc [~alangates]/[~ekoifman].

> add rename database functionality
> ---------------------------------
>
>                 Key: HIVE-4847
>                 URL: https://issues.apache.org/jira/browse/HIVE-4847
>             Project: Hive
>          Issue Type: New Feature
>    Affects Versions: 0.11.0
>            Reporter: Greg Rahn
>            Assignee: Teddy Choi
>            Priority: Minor
>         Attachments: HIVE-4847.1.patch.txt, HIVE-4847.2.patch.txt
>
>
> There seems to be no way to rename a database in Hive, functionality to do so would be
nice.
> Proposed syntax:
> ALTER DATABASE dbname RENAME TO newdbname;



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