[jira] [Commented] (CALCITE-2677) Struct types with one field are not mapped correctly to Java Classes

["Stamatis Zampetakis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-2677?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16737164#comment-16737164 ] 

Stamatis Zampetakis commented on CALCITE-2677:
----------------------------------------------

Hi [~julianhyde], to illustrate the problem of bad Java types on structs with one field, let's consider the following query:

{code:sql}
 select * from (values
    (1, ROW(1)),
    (2, ROW(2))) as v(id,struct);
{code}

Without the fix in this PR, this query fails at runtime with a ClassCastException. 

I updated the PR with this test case and I added an additional fix related with CALCITE-2776. 

Can you please have a look when you find some time?

 

> Struct types with one field are not mapped correctly to Java Classes
> --------------------------------------------------------------------
>
>                 Key: CALCITE-2677
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2677
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.17.0
>            Reporter: Stamatis Zampetakis
>            Assignee: Julian Hyde
>            Priority: Major
>              Labels: easy-fix, pull-request-available
>
> There are various places in the code where given a RelDataType we need to obtain the respective Java Class/Type. This is done mainly through JavaTypeFactory#getJavaClass. For the Calcite runtime it passes through PhysType#fieldClass and PhysType#getJavaFieldType. 
> However, when the RelDataType is a struct of one field the returned Class/Type is not the correct one since the struct type is simplified to the type of its component. 



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