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https://issues.apache.org/jira/browse/FLINK-33541?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17789325#comment-17789325
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Benchao Li commented on FLINK-33541:
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{quote}I notice currently the CAST rule is correct. It forbids casting from not
null to nullable. The root cause is not IF but is RAND_INTEGER
{quote}
I don't agree on this, casting not null to nullable should be valid. The
opposite should be invalid.
{quote}Actually, the result type of RAND and RAND_INTEGER should depend on the
types of arguments.
{quote}
In this case, the argument is literal which is not null, so the result type is
not null is ok. And I don't see many usages to pass in a nullable field as
argument.
{quote}when codegen operator RAND, the return type of RAND(0) is always
"nullable" in `RandCallGen`.
{quote}
Isn't this is the root cause?
> RAND_INTEGER can't be existed in a IF statement
> ------------------------------------------------
>
> Key: FLINK-33541
> URL: https://issues.apache.org/jira/browse/FLINK-33541
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / API
> Affects Versions: 1.17.0, 1.18.0
> Reporter: Guojun Li
> Priority: Major
> Labels: pull-request-available
>
> The minimum produce steps:
> Flink SQL> select if(1=1, rand_integer(100), 0);
> [ERROR] Could not execute SQL statement. Reason:
> java.lang.Exception: Unsupported operand types: IF(boolean, INT, INT NOT NULL)
>
> But we do not see the exception reported in 1.14, not sure which version this
> bug was introduced.
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