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https://issues.apache.org/jira/browse/HIVE-5317?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13772115#comment-13772115
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Owen O'Malley commented on HIVE-5317:
-------------------------------------

Bikas,
  In Hive if the client disappears, the query fails, because the final work 
(output promotion, display to the user) is done by the client. Also don't 
forget that a single query may be composed on many MR jobs, although obviously 
that changes on Tez. 

The transaction id is global for all of the tasks working on the same query. 

The metastore's data in stored in an underlying SQL database, so the 
transaction information will need to be there also.
                
> Implement insert, update, and delete in Hive with full ACID support
> -------------------------------------------------------------------
>
>                 Key: HIVE-5317
>                 URL: https://issues.apache.org/jira/browse/HIVE-5317
>             Project: Hive
>          Issue Type: New Feature
>            Reporter: Owen O'Malley
>            Assignee: Owen O'Malley
>         Attachments: InsertUpdatesinHive.pdf
>
>
> Many customers want to be able to insert, update and delete rows from Hive 
> tables with full ACID support. The use cases are varied, but the form of the 
> queries that should be supported are:
> * INSERT INTO tbl SELECT …
> * INSERT INTO tbl VALUES ...
> * UPDATE tbl SET … WHERE …
> * DELETE FROM tbl WHERE …
> * MERGE INTO tbl USING src ON … WHEN MATCHED THEN ... WHEN NOT MATCHED THEN 
> ...
> * SET TRANSACTION LEVEL …
> * BEGIN/END TRANSACTION
> Use Cases
> * Once an hour, a set of inserts and updates (up to 500k rows) for various 
> dimension tables (eg. customer, inventory, stores) needs to be processed. The 
> dimension tables have primary keys and are typically bucketed and sorted on 
> those keys.
> * Once a day a small set (up to 100k rows) of records need to be deleted for 
> regulatory compliance.
> * Once an hour a log of transactions is exported from a RDBS and the fact 
> tables need to be updated (up to 1m rows)  to reflect the new data. The 
> transactions are a combination of inserts, updates, and deletes. The table is 
> partitioned and bucketed.

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