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https://issues.apache.org/jira/browse/FLINK-31653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17706711#comment-17706711
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Yuan Kui commented on FLINK-31653:
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[~martijnvisser] It does seem to be duplicated with the others, I will mark
this jira duplicated with the smaller jira.
> Using`if` statement for a string subtype of the row type may meet npe in code
> generated by codegen
> --------------------------------------------------------------------------------------------------
>
> Key: FLINK-31653
> URL: https://issues.apache.org/jira/browse/FLINK-31653
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / Planner
> Affects Versions: 1.16.1, 1.15.4, 1.18.0, 1.17.1
> Reporter: Yuan Kui
> Assignee: Yuan Kui
> Priority: Critical
> Fix For: 1.16.2, 1.18.0, 1.17.1, 1.15.5
>
> Attachments: StreamExecCalc$17, image-2023-03-29-15-33-37-983.png,
> image-2023-03-29-16-06-19-351.png
>
>
> When I use the `if` statement for the string subtype of the row type, the
> code generated by `IfCallGen` may meet npe. The case is:
> {code:java}
> -- if the value of 'nested' colmun is row(null, 10), the job will meet npe
> CREATE TABLE NestedTable (
> nested row<name string, `value` int>
> ) WITH (
> ...
> );
> select
> if (nested.name is null, 'JKL', nested.name) AS nestedName
> from NestedTable {code}
> Three conditions are required to reproduce the bug:
> 1、use `if` statement
> 2、string subtype of row type
> 3、the value of string subtype element is null
>
> After excluding the effect of java code spilitter, the picture shows the
> original code generated by codegen(you can find the complete code generated
> by codegen in attached file: [^StreamExecCalc$17])，the assignment logic for
> `isNull$7` is between the line 140 and the line 152, so the value of
> `isNull$7` in line 94 is always false(the default value), and the line 96
> will meet npe when `result$7` is null.
> !image-2023-03-29-16-06-19-351.png|width=703,height=533!
> To fix this issue, we can change the location of the logic to generate casted
> codes in `IfCallGen`, like this:
> !image-2023-03-29-15-33-37-983.png|width=829,height=361!
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