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From "Gunther Hagleitner (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-4271) Limit precision of decimal type
Date Mon, 01 Apr 2013 08:05:16 GMT

     [ https://issues.apache.org/jira/browse/HIVE-4271?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Gunther Hagleitner updated HIVE-4271:
-------------------------------------

    Attachment: HIVE-4271.1.patch
    
> Limit precision of decimal type
> -------------------------------
>
>                 Key: HIVE-4271
>                 URL: https://issues.apache.org/jira/browse/HIVE-4271
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Gunther Hagleitner
>            Assignee: Gunther Hagleitner
>         Attachments: HIVE-4271.1.patch
>
>
> The current decimal implementation does not limit the precision of the numbers. This
has a number of drawbacks. A maximum precision would allow us to:
> - Have SerDes/filformats store decimals more efficiently
> - Speed up processing by implementing operations w/o generating java BigDecimals
> - Simplify extending the datatype to allow for decimal(p) and decimal(p,s)
> - Write a more efficient BinarySortable SerDe for sorting/grouping/joining
> Exact numeric datatype are typically used to represent money, so if the limit is high
enough it doesn't really become an issue.
> A typical representation would pack 9 decimal digits in 4 bytes. So, with 2 longs we
can represent 36 digits - which is what I propose as the limit.
> Final thought: It's easier to restrict this now and have the option to do the things
above than to try to do so once people start using the datatype.

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