Skip to content

fix: Avoid unnecessary type casts in concat_ws #20436

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
neilconway wants to merge 3 commits into
base: main
Choose a base branch
from
+380 −68
Open

fix: Avoid unnecessary type casts in concat_ws #20436

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
b976e16
Initial work
neilconway Feb 19, 2026
51a7e87
Fix bug with NULL separators, add tests
neilconway Feb 19, 2026
9c0b4f4
cargo fmt
neilconway Feb 19, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
42 changes: 19 additions & 23 deletions datafusion/functions/src/string/concat.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -88,37 +88,33 @@ impl ScalarUDFImpl for ConcatFunc {
&self.signature
}

/// Match the return type to the input types to avoid unnecessary casts. On
/// mixed inputs, prefer Utf8View; prefer LargeUtf8 over Utf8 to avoid
/// potential overflow on LargeUtf8 input.
fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
use DataType::*;
let mut dt = &Utf8;
arg_types.iter().for_each(|data_type| {
if data_type == &Utf8View {
dt = data_type;
}
if data_type == &LargeUtf8 && dt != &Utf8View {
dt = data_type;
}
});

Ok(dt.to_owned())
if arg_types.contains(&Utf8View) {
Ok(Utf8View)
} else if arg_types.contains(&LargeUtf8) {
Ok(LargeUtf8)
} else {
Ok(Utf8)
}
}

/// Concatenates the text representations of all the arguments. NULL arguments are ignored.
/// concat('abcde', 2, NULL, 22) = 'abcde222'
fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
let ScalarFunctionArgs { args, .. } = args;

let mut return_datatype = DataType::Utf8;
args.iter().for_each(|col| {
if col.data_type() == DataType::Utf8View {
return_datatype = col.data_type();
}
if col.data_type() == DataType::LargeUtf8
&& return_datatype != DataType::Utf8View
{
return_datatype = col.data_type();
}
});
let return_datatype = if args.iter().any(|c| c.data_type() == DataType::Utf8View)
{
DataType::Utf8View
} else if args.iter().any(|c| c.data_type() == DataType::LargeUtf8) {
DataType::LargeUtf8
} else {
DataType::Utf8
};

let array_len = args.iter().find_map(|x| match x {
ColumnarValue::Array(array) => Some(array.len()),
Expand Down Expand Up @@ -247,7 +243,7 @@ impl ScalarUDFImpl for ConcatFunc {
builder.append_offset();
}

let string_array = builder.finish();
let string_array = builder.finish(None);
Ok(ColumnarValue::Array(Arc::new(string_array)))
}
DataType::LargeUtf8 => {
Expand Down
Loading