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Posted to issues@hive.apache.org by "Vihang Karajgaonkar (JIRA)" <ji...@apache.org> on 2018/03/02 19:55:00 UTC

[jira] [Commented] (HIVE-18685) Add catalogs to metastore

    [ https://issues.apache.org/jira/browse/HIVE-18685?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16384079#comment-16384079 ] 

Vihang Karajgaonkar commented on HIVE-18685:
--------------------------------------------

Thanks [~alangates] for taking this up. I think this would be a good addition. I went through the doc attached and all the comments above and I have some questions:

bq. It will not be possible to address a table as catalog.database.table.  Which catalog you are connected to will be determine when the session is started and is immutable initially.
If you cannot address table using catalog.database.table how would a user be able to issue cross catalog queries. eg. join between tables across catalogs?

Regarding catalog location,
Does it mean that all databases/tables created under a catalog default to a location of catalog? As a corollary to this, if a user gives a location which doesn't make sense with respect to the catalog's location (catalogs being the logical separation of systems) should we have hooks which can allow us to enforce the location of the catalogs?

Should the catalog have a owner as well? Who is allowed to create/drop the catalog?

> Add catalogs to metastore
> -------------------------
>
>                 Key: HIVE-18685
>                 URL: https://issues.apache.org/jira/browse/HIVE-18685
>             Project: Hive
>          Issue Type: New Feature
>          Components: Metastore, Parser, Security, SQL
>    Affects Versions: 3.0.0
>            Reporter: Alan Gates
>            Assignee: Alan Gates
>            Priority: Major
>         Attachments: HMS Catalog Design Doc.pdf
>
>
> SQL supports two levels of namespaces, called in the spec catalogs and schemas (with schema being equivalent to Hive's database).  I propose to add the upper level of catalog.  The attached design doc covers the use cases, requirements, and brief discussion of how it will be implemented in a backwards compatible way.



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