[jira] [Commented] (CALCITE-2311) case when returns redundant white space

["Julian Hyde (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-2311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16476176#comment-16476176 ] 

Julian Hyde commented on CALCITE-2311:
--------------------------------------

I agree this behavior is surprising, but it is not a bug. The return type of the CASE expression is {{CHAR(3)}}. The result of evaluating {{CAST('a' AS CHAR(3))}} is {{'a  '}}.

> case when returns redundant white space
> ---------------------------------------
>
>                 Key: CALCITE-2311
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2311
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.12.0
>            Reporter: pengzhiwei
>            Assignee: Julian Hyde
>            Priority: Major
>             Fix For: 1.17.0
>
>
> If the case-when expression has two branches which returns string literal,redundant white space will append to the short string literal  after the ReduceExpressionsRule. For example:
> {code:java}
> case when id>0 then 'a' else 'abc' end{code}
> will actually be convert to 
> {code:java}
> case when id>0 then 'a  ' else 'abc' end{code}
>  
> The reason is that the type of  'a' is CHAR(1),but CHAR(3) for 'abc',so the return type of  the case-when is CHAR(3). The RexBuilder#ensureType() method append a cast convertion for 'a' to cast it to CHAR(3) type.The ReduceExpressionsRule execute the cast convertion which fill two whilte space to 'a'.



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