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From "Edward Capriolo (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5317) Implement insert, update, and delete in Hive with full ACID support
Date Mon, 18 Nov 2013 18:57:29 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5317?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13825619#comment-13825619
] 

Edward Capriolo commented on HIVE-5317:
---------------------------------------

By the way. I do work like this very often, and having tables that update periodically cause
a lot of problems. The first is when you have to re-compute a result 4 days later.

You do not want a fresh up-to-date table, you want the table as it existed 4 days ago. When
you want to troubleshoot a result you do not want your intermediate tables trampled over.
When you want to rebuild a months worth of results you want to launch 31 jobs in parallel
not 31 jobs in series. 

In fact in programming hive I suggest ALWAYS partitioning this dimension tables by time and
NOT doing what this ticket is describing for the reasons above (and more)

> 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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