[jira] [Commented] (FLINK-15266) NPE in blink planner code gen

["Jark Wu (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-15266?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16996932#comment-16996932 ] 

Jark Wu commented on FLINK-15266:
---------------------------------

Thanks for reporting this issue. I verified in master branch and reproduced this exception. I think it is a bug in code generation.

> NPE in blink planner code gen
> -----------------------------
>
>                 Key: FLINK-15266
>                 URL: https://issues.apache.org/jira/browse/FLINK-15266
>             Project: Flink
>          Issue Type: Bug
>          Components: Table SQL / Runtime
>    Affects Versions: 1.9.1
>            Reporter: Benchao Li
>            Priority: Major
>
> `cast` function in blink planner and old planner are different:
> in legacy planner:
> cast('' as int)  ->  throw NumberFormatException
> cast(null as int) -> throw NullPointerException
> cast('abc' as int)  -> throw NumberFormatException
> but in blink planner:
> cast('' as int)  ->  return null
> cast(null as int) -> return null
> cast('abc' as int)  -> return null
> A step forward:
> ```
> create table source {
>   age int,
>   id varchar
> };
> select case when age < 20 then cast(id as bigint) else 0 end from source;
> ```
> queries like above will throw NPE because we will try assign a `null` to a `long` field when the input satisfy `age < 20`.



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