dawidwys commented on pull request #12649:
URL: https://github.com/apache/flink/pull/12649#issuecomment-644618279
Yes, but does it always. We want that behaviour only when accessing the
field.
Imagine a user function that accepts `ADDRESS(id INT NOT NULL, city STRING)`.
```
class UDF extends ScalarFunction {
public Object eval(Address address) {
if (address != null) {
// based on the type I know address.id is NOT NULL here
int id = address.id;
}
}
}
```
but this is not possible in Calcite. There is no way to construct a
`ADDRESS(id INT NOT NULL, city STRING)`. It will be changed to `ADDRESS(id INT,
city STRING)`. And based on that there is no way to have the behaviour as
above. The id is always nullable.
On the other hand I want the type adjusted if I pass the field only, as this
might be null without additional checks:
```
class UDF2 extends ScalarFunction {
public Object eval(int id {
}
}
// This is illegal. We can not ensure that t.address.id is NOT NULL
SELECT UDF2(t.address.id) FROM test t;
```
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