[jira] [Commented] (ARROW-14110) [C++] Decimal promotion rules should consider inflating type

["David Li (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-14110?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17419479#comment-17419479 ] 

David Li commented on ARROW-14110:
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ARROW-13390 will do this in some cases but not all. Somewhat related, I also filed ARROW-14105 to try to reconcile all these rules in general.

> [C++] Decimal promotion rules should consider inflating type
> ------------------------------------------------------------
>
>                 Key: ARROW-14110
>                 URL: https://issues.apache.org/jira/browse/ARROW-14110
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: C++
>            Reporter: Weston Pace
>            Priority: Major
>              Labels: kernel
>
> I'm not sure how strongly I feel about this but, for example:
> {code:python}
> Decimal(20, 4) / Decimal(20, 4) => Decimal(41, 21)
> {code}
> Decimal(20, 4) is in range for 128 but Decimal(41, 21) is out of range for 128 (but in range for 256).
> Currently calling divide with two 128 bit decimals will fail but it could promote to a decimal 256.



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