bert-beyondloops opened a new issue, #16474:
URL: https://github.com/apache/datafusion/issues/16474
### Describe the bug
When using the array_has function with an empty list, the result is <null>
Currently :
array_has([], 1) => **null**.
array_has(null, 1) => null.
In my opinion, it should **_only_** return null when the list itself is null.
In duckDb:
array_has([], 1) => **false**.
array_has(null, 1) => null.
### To Reproduce
```
CREATE TABLE foo ( bar INTEGER[] );
INSERT INTO foo VALUES
( [1, 3, 5]),
( []),
( null)
;
SELECT bar, IFNULL(CAST(list_contains(bar, 1) AS VARCHAR), 'null') FROM foo;
```
will result in :
```
+-----------+-----------------------------------------------+
| bar | nvl(array_has(foo.bar,Int64(1)),Utf8("null")) |
+-----------+-----------------------------------------------+
| [1, 3, 5] | true |
| [] | null |
| | null |
+-----------+-----------------------------------------------+
```
whereas for example in duckDb you get :
```
┌───────────┬──────────────────────────────────────────────────────────┐
│ bar │ COALESCE(CAST(list_contains(bar, 1) AS VARCHAR), 'null') │
│ int32[] │ varchar │
├───────────┼──────────────────────────────────────────────────────────┤
│ [1, 3, 5] │ true │
│ [] │ false │
│ │ null │
└───────────┴──────────────────────────────────────────────────────────┘
```
### Expected behavior
array_has([], 1) => false.
array_has(null, 1) => null.
### Additional context
According to me, the issue is situated in the
`array_has_dispatch_for_scalar` method :
```
...
for (i, offset) in offsets.windows(2).enumerate() {
let start = offset[0].to_usize().unwrap();
let end = offset[1].to_usize().unwrap();
let length = end - start;
// For non-nested list, length is 0 for null
if length == 0 {
continue;
}
let sliced_array = eq_array.slice(start, length);
final_contained[i] = Some(sliced_array.true_count() > 0);
}
...
```
There is no distinction between null or length = 0.
You cannot only look at the offset difference. You have to look at the
validity buffer as well.
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