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From "Xuefu Zhang (JIRA)" <>
Subject [jira] [Commented] (HIVE-3976) Support specifying scale and precision with Hive decimal type
Date Fri, 18 Oct 2013 19:27:50 GMT


Xuefu Zhang commented on HIVE-3976:

Thanks for clarifying your question.

If the comment is about HIVE-5564, I think it might be better to move the discussion there.
Nevertheless, as short response to your comments:

1. The question of backward compatibility was brought up in day 1, and detailed in the functional
document. I think there is an agreement that no known customer is seriously using  decimal,
and break of the backward compatibility isn't a concern for this project. Unless you want
to bring up that discussion again, let's move forward without further concerning.

2. Internally, typeinfo object for "decimal(65,30)" is not user facing, (i.e, when specifying
column type), but for internal default when serve doesn't know the type (for instance, the
decimal type returned by non-generic udf). To further clarify, externally user specifying
"decimal" for column name, server interprets it as "decimal(10, 0)"; internally, if server
cannot determine the exact type, then decimal(65,30) is assumed. 

3. In my opinion, fixing the error in HIVE-5564 is better than assuming (65,30) as the user
default due to its usability problem. BTW, the fix could have been included in this patch,
so the "error" would not have come in the picture at all.

I think I should put the clarification in #2 in the document as well. Let me know if you have
more questions.

> Support specifying scale and precision with Hive decimal type
> -------------------------------------------------------------
>                 Key: HIVE-3976
>                 URL:
>             Project: Hive
>          Issue Type: New Feature
>          Components: Query Processor, Types
>    Affects Versions: 0.11.0
>            Reporter: Mark Grover
>            Assignee: Xuefu Zhang
>             Fix For: 0.13.0
>         Attachments: HIVE-3976.1.patch, HIVE-3976.2.patch, HIVE-3976.3.patch, HIVE-3976.4.patch,
HIVE-3976.5.patch, HIVE-3976.6.patch, HIVE-3976.7.patch, HIVE-3976.8.patch, HIVE-3976.9.patch,
HIVE-3976.patch, remove_prec_scale.diff
> HIVE-2693 introduced support for Decimal datatype in Hive. However, the current implementation
has unlimited precision and provides no way to specify precision and scale when creating the
> For example, MySQL allows users to specify scale and precision of the decimal datatype
when creating the table:
> {code}
> CREATE TABLE numbers (a DECIMAL(20,2));
> {code}
> Hive should support something similar too.

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