Hi, Benchao, thank you for your report.
It looks egacy planner and blink planner have different behavior.
Could you create an issue in https://issues.apache.org/jira/browse/FLINK
<https://issues.apache.org/jira/browse/FLINK> ?
> On Dec 15, 2019, at 16:17, Benchao Li <libenc...@gmail.com> wrote:
>
> hi all,
>
> We are using 1.9.0 blink planner, and find flink will throw NPE when we use
> the following SQL:
>
> ```
> create table source {
> age int,
> id varchar
> };
> select *case when age < 20 then cast(id as bigint) else 0 end* from source;
> ```
>
> After debugging the Janino generated code, I find that NPE's reason is that
> `BinaryStringUtil.toLong` returns `null`, and we assign this result to a
> `long` field.
>
> Then a tried old planner, it throw a `java.lang.NumberFormatException` when
> casting a blank string to int.
> And also tried other illegal casting in blink, which come out to be `null`.
>
> So, here is my question:
> Obviously, this is a bug in blink planner, and we should fix that. But we
> have two ways to fix this:
> 1, make behavior of cast behave like before, which produces `null`,
> 2, change the behavior of blink planner to align with old planner, which
> produces `NumberFormatException`.
>
>
>
> Benchao Li
> School of Electronics Engineering and Computer Science, Peking University
> Tel:+86-15650713730
> Email: libenc...@gmail.com; libenc...@pku.edu.cn
