[jira] [Comment Edited] (ARROW-14518) [Ruby] ArrayBuilder doesn't work correctly with Decimal

["Kenta Murata (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-14518?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17436352#comment-17436352 ] 

Kenta Murata edited comment on ARROW-14518 at 10/30/21, 5:38 PM:
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A {{BigDecimal}} number manages only its precision in its decimal notation.

We can get the precision of a {{BigDecimal}} number by {{BigDecimal#precision}} method.

{{irb(main):001:0> BigDecimal("1.1").precision}}
{{=> 2}}

But, the {{BigDecimal#precision}} method does not count the trailing zeros.

{{irb(main):002:0> BigDecimal("1.10").precision}}
{{=> 2}}

The reason why a {{BigDecimal}} number doesn't have the scale property may be a {{BigDecimal}} number isn't a fixed-precision number.


was (Author: mrkn):
A {{BigDecimal}} number manages only its precision in its decimal notation.

We can get the precision of a {{BigDecimal}} number by {{BigDecimal#precision}} method.

{{irb(main):001:0> BigDecimal("1.1").precision}}
{{=> 2}}

But, a {{BigDecimal#precision}} does not count the trailing zeros.

{{irb(main):002:0> BigDecimal("1.10").precision}}
{{=> 2}}

The reason why a {{BigDecimal}} number doesn't have the scale property may be a {{BigDecimal}} number isn't a fixed-precision number.

> [Ruby] ArrayBuilder doesn't work correctly with Decimal
> -------------------------------------------------------
>
>                 Key: ARROW-14518
>                 URL: https://issues.apache.org/jira/browse/ARROW-14518
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: Ruby
>            Reporter: Kanstantsin Ilchanka
>            Priority: Minor
>
> When trying to convert raw data with decimal values to Arrow::Table error received
>  
> {code:java}
> Arrow::Table.new(x: [BigDecimal('1.1')])
> ArgumentError: wrong arguments: Arrow::Decimal128ArrayBuilder#initialize(): available signatures: (data_type: interface(Arrow::Decimal128DataType(GArrowDecimal128DataType)))
> {code}
> I guess this is because Decimal128ArrayBuilder expects Decimal128DataType in initialiser, however I'm not sure how to correctly and effectively detect precision and scale from array of BigDecimal
>  
> {code:java}
> Arrow::VERSION
> => "5.0.0"{code}



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