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
