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Date: Thu, 20 Feb 2014 19:29:26 +0000 (UTC)
From: "Sushanth Sowmyan (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Message-ID: <JIRA.12694546.1392143152546.75226.1392924566993@arcas>
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Subject: [jira] [Updated] (HIVE-6405) Support append feature for HCatalog
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     [ https://issues.apache.org/jira/browse/HIVE-6405?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sushanth Sowmyan updated HIVE-6405:
-----------------------------------

    Attachment:     (was: HIVE-6405.patch)

> Support append feature for HCatalog
> -----------------------------------
>
>                 Key: HIVE-6405
>                 URL: https://issues.apache.org/jira/browse/HIVE-6405
>             Project: Hive
>          Issue Type: Bug
>          Components: HCatalog, Metastore, Query Processor, Thrift API
>            Reporter: Sushanth Sowmyan
>            Assignee: Sushanth Sowmyan
>
> HCatalog currently treats all tables as "immutable" - i.e. all tables and partitions can be written to only once, and not appended. The nuances of what this means is as follows:
>  * A non-partitioned table can be written to, and data in it is never updated from then on unless you drop and recreate.
>  * A partitioned table may support "appending" of a sort in a manner by adding new partitions to the table, but once written, the partitions themselves cannot have any new data added to them.
> Hive, on the other hand, does allow us to "INSERT INTO" into a table, thus allowing us append semantics. There is benefit to both of these models, and so, our goal is as follows:
> a) Introduce a notion of an immutable table, wherein all tables are not immutable by default, and have this be a table property. If this property is set for a table, and we attempt to write to a table that already has data (or a partition), disallow "INSERT INTO" into it from hive. This property being set will allow hive to mimic HCatalog's current immutable-table property. (I'm going to create a separate sub-task to cover this bit, and focus on the HCatalog-side on this jira)
> b) As long as that flag is not set, HCatalog should be changed to allow appends into it as well, and not simply error out if data already exists in a table.


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