liukun4515 commented on code in PR #10193:
URL: https://github.com/apache/datafusion/pull/10193#discussion_r1580661398
##########
datafusion/functions/src/math/random.rs:
##########
@@ -64,45 +61,9 @@ impl ScalarUDFImpl for RandomFunc {
Ok(Float64)
}
- fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
- random(args)
- }
-}
-
-/// Random SQL function
-fn random(args: &[ColumnarValue]) -> Result<ColumnarValue> {
- let len: usize = match &args[0] {
- ColumnarValue::Array(array) => array.len(),
- _ => return exec_err!("Expect random function to take no param"),
- };
- let mut rng = thread_rng();
- let values = iter::repeat_with(|| rng.gen_range(0.0..1.0)).take(len);
- let array = Float64Array::from_iter_values(values);
- Ok(ColumnarValue::Array(Arc::new(array)))
-}
-
-#[cfg(test)]
-mod test {
- use std::sync::Arc;
-
- use arrow::array::NullArray;
-
- use datafusion_common::cast::as_float64_array;
- use datafusion_expr::ColumnarValue;
-
- use crate::math::random::random;
-
- #[test]
- fn test_random_expression() {
- let args = vec![ColumnarValue::Array(Arc::new(NullArray::new(1)))];
- let array = random(&args)
- .expect("failed to initialize function random")
- .into_array(1)
- .expect("Failed to convert to array");
- let floats =
- as_float64_array(&array).expect("failed to initialize function
random");
-
- assert_eq!(floats.len(), 1);
- assert!(0.0 <= floats.value(0) && floats.value(0) < 1.0);
+ fn invoke(&self, _args: &[ColumnarValue]) -> Result<ColumnarValue> {
Review Comment:
> We have test like
>
> ```
> query II
> SELECT octet_length(uuid()), length(uuid())
> ----
> 36 36
> ```
I means the `uuid` function is also `invoked once per row rather than once
per batch` like `random()` function mentioned by alamb.
I test the function in the spark
```
spark-sql> desc test;
col1 int NULL
Time taken: 0.065 seconds, Fetched 1 row(s)
spark-sql> select * from test;
1
2
spark-sql> select *,uuid() from test;
1 6b04b66c-2e6c-4925-8b18-a9d51d5ed80a
2 3e0be0c2-9ff2-422a-8f3f-5cdb6551264b
```
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