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https://issues.apache.org/jira/browse/HIVE-3976?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14551959#comment-14551959
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Zhongshuai Pei commented on HIVE-3976:
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[~xuefu.w...@kodak.com] I read your design document "Hive Decimal 
Precision/Scale Support", but i did not find the rule of operations  that the 
doc describes in Hive code :
{noformat}
Operation   Result precision                                    Result scale
e1 + e2       max(s1, s2) + max(p1-s1, p2-s2) + 1   max(s1, s2)
e1 - e2        max(s1, s2) + max(p1-s1, p2-s2) + 1   max(s1, s2)
e1 * e2        p1 + p2 + 1                                           s1 + s2
e1 / e2        p1 - s1 + s2 + max(6, s1 + p2 + 1)       max(6, s1 + p2 + 1)
e1 % e2      min(p1-s1, p2 -s2) + max( s1,s2 )        max(s1, s2)
{noformat}
Did it changed?

> Support specifying scale and precision with Hive decimal type
> -------------------------------------------------------------
>
>                 Key: HIVE-3976
>                 URL: https://issues.apache.org/jira/browse/HIVE-3976
>             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-3976.10.patch, 
> HIVE-3976.11.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 table.
> 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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