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https://issues.apache.org/jira/browse/HIVE-5317?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13772086#comment-13772086
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Bikas Saha commented on HIVE-5317:
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Some questions which I am sure have been considered but are not clear in the 
document.
Should metastore heartbeat be in the job itself and not the client since the 
job is the source of truth and the client can disappear. What happens if the 
client disappears but the job completes with success and manages to promote the 
output files?
Is transaction id per file or per metastore? Where does the metastore recover 
the last transaction id(s) from after restart?
                
> 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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