EeshanBembi commented on code in PR #18137:
URL: https://github.com/apache/datafusion/pull/18137#discussion_r2658921205
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datafusion/functions/src/string/concat.rs:
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@@ -65,13 +71,64 @@ impl Default for ConcatFunc {
impl ConcatFunc {
pub fn new() -> Self {
- use DataType::*;
Self {
- signature: Signature::variadic(
- vec![Utf8View, Utf8, LargeUtf8],
- Volatility::Immutable,
- ),
+ signature: Signature::user_defined(Volatility::Immutable),
+ }
+ }
+
+ /// Get the string type with highest precedence: Utf8View > LargeUtf8 >
Utf8
+ fn get_string_type_precedence(&self, arg_types: &[DataType]) -> DataType {
+ use DataType::*;
+
+ for data_type in arg_types {
+ if data_type == &Utf8View {
+ return Utf8View;
+ }
+ }
+
+ for data_type in arg_types {
+ if data_type == &LargeUtf8 {
+ return LargeUtf8;
+ }
+ }
+
+ Utf8
+ }
+
+ /// Concatenate array arguments
+ fn concat_arrays(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
+ if args.is_empty() {
+ return plan_err!("concat requires at least one argument");
}
+
+ // Convert ColumnarValue arguments to ArrayRef
+ let arrays: Result<Vec<Arc<dyn Array>>> = args
+ .iter()
+ .map(|arg| match arg {
+ ColumnarValue::Array(arr) => Ok(Arc::clone(arr)),
+ ColumnarValue::Scalar(scalar) => scalar.to_array_of_size(1),
+ })
+ .collect();
+ let arrays = arrays?;
+
+ // Check if all arrays are null - concat errors in this case
Review Comment:
Yes, this matches PostgreSQL's behavior. I've added a comment to clarify:
` // This matches PostgreSQL behavior where concat() with all NULL values
returns an error`
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