perf: optimize array_replace for scalar needle

datafusion/functions-nested/src/replace.rs

@@ -19,22 +19,20 @@
 
 use arrow::array::{
     Array, ArrayRef, AsArray, Capacities, GenericListArray, MutableArrayData,
-    NullBufferBuilder, OffsetSizeTrait, new_null_array,
+    NullBufferBuilder, OffsetBufferBuilder, OffsetSizeTrait, Scalar, new_null_array,
 };
-use arrow::datatypes::{DataType, Field};
-
 use arrow::buffer::OffsetBuffer;
+use arrow::datatypes::{DataType, Field};
 use datafusion_common::cast::as_int64_array;
 use datafusion_common::utils::ListCoercion;
-use datafusion_common::{Result, exec_err, utils::take_function_args};
+use datafusion_common::{Result, ScalarValue, exec_err, utils::take_function_args};
 use datafusion_expr::{
     ArrayFunctionArgument, ArrayFunctionSignature, ColumnarValue, Documentation,
     ScalarFunctionArgs, ScalarUDFImpl, Signature, TypeSignature, Volatility,
 };
 use datafusion_macros::user_doc;
 
 use crate::utils::compare_element_to_list;
-use crate::utils::make_scalar_function;
 
 use std::sync::Arc;
 
@@ -125,7 +123,27 @@ impl ScalarUDFImpl for ArrayReplace {
     }
 
     fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
-        make_scalar_function(array_replace_inner)(&args.args)
+        let [list_arg, from_arg, to_arg] = take_function_args(self.name(), &args.args)?;
+        let num_rows = args.number_rows;
+        let list_array = list_arg.to_array(num_rows)?;
+        match (from_arg, to_arg) {
+            (ColumnarValue::Scalar(scalar_from), ColumnarValue::Scalar(scalar_to)) => {
+                let result = array_replace_with_scalar_args(
+                    &list_array,
+                    scalar_from,
+                    scalar_to,
+                    1i64,
+                )?;
+                Ok(ColumnarValue::Array(result))
+            }
+            (from_arg, to_arg) => {
+                let from_array = from_arg.to_array(num_rows)?;
+                let to_array = to_arg.to_array(num_rows)?;
+                let result =
+                    array_replace_internal(&list_array, &from_array, &to_array, &[1])?;
+                Ok(ColumnarValue::Array(result))
+            }
+        }
     }
 
     fn aliases(&self) -> &[String] {
@@ -200,7 +218,38 @@ impl ScalarUDFImpl for ArrayReplaceN {
     }
 
     fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
-        make_scalar_function(array_replace_n_inner)(&args.args)
+        let [list_arg, from_arg, to_arg, max_arg] =
+            take_function_args(self.name(), &args.args)?;
+        let num_rows = args.number_rows;
+        let list_array = list_arg.to_array(num_rows)?;
+        match (from_arg, to_arg, max_arg) {
+            (
+                ColumnarValue::Scalar(scalar_from),
+                ColumnarValue::Scalar(scalar_to),
+                ColumnarValue::Scalar(scalar_max),
+            ) => {
+                let ScalarValue::Int64(Some(n)) = scalar_max else {
+                    // null max means no replacements
+                    return Ok(ColumnarValue::Array(list_array));
+                };
+                let result = array_replace_with_scalar_args(
+                    &list_array,
+                    scalar_from,
+                    scalar_to,
+                    *n,
+                )?;
+                Ok(ColumnarValue::Array(result))
+            }
+            (from_arg, to_arg, max_arg) => {
+                let from_array = from_arg.to_array(num_rows)?;
+                let to_array = to_arg.to_array(num_rows)?;
+                let max_array = max_arg.to_array(num_rows)?;
+                let arr_n = as_int64_array(&max_array)?.values().to_vec();
+                let result =
+                    array_replace_internal(&list_array, &from_array, &to_array, &arr_n)?;
+                Ok(ColumnarValue::Array(result))
+            }
+        }
     }
 
     fn aliases(&self) -> &[String] {
@@ -273,7 +322,31 @@ impl ScalarUDFImpl for ArrayReplaceAll {
     }
 
     fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
-        make_scalar_function(array_replace_all_inner)(&args.args)
+        let [list_arg, from_arg, to_arg] = take_function_args(self.name(), &args.args)?;
+        let num_rows = args.number_rows;
+        let list_array = list_arg.to_array(num_rows)?;
+        match (from_arg, to_arg) {
+            (ColumnarValue::Scalar(scalar_from), ColumnarValue::Scalar(scalar_to)) => {
+                let result = array_replace_with_scalar_args(
+                    &list_array,
+                    scalar_from,
+                    scalar_to,
+                    i64::MAX,
+                )?;
+                Ok(ColumnarValue::Array(result))
+            }
+            (from_arg, to_arg) => {
+                let from_array = from_arg.to_array(num_rows)?;
+                let to_array = to_arg.to_array(num_rows)?;
+                let result = array_replace_internal(
+                    &list_array,
+                    &from_array,
+                    &to_array,
+                    &[i64::MAX],
+                )?;
+                Ok(ColumnarValue::Array(result))
+            }
+        }
     }
 
     fn aliases(&self) -> &[String] {
@@ -343,7 +416,11 @@ fn general_replace<O: OffsetSizeTrait>(
 
         let original_idx = O::usize_as(0);
         let replace_idx = O::usize_as(1);
-        let n = arr_n[row_index];
+        let n = if arr_n.len() == 1 {
+            arr_n[0]
+        } else {
+            arr_n[row_index]
+        };
         let mut counter = 0;
 
         // All elements are false, no need to replace, just copy original data
@@ -412,63 +489,154 @@ fn general_replace<O: OffsetSizeTrait>(
     )?))
 }
 
-fn array_replace_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
-    let [array, from, to] = take_function_args("array_replace", args)?;
+/// Replaces up to `max_replacements` occurrences of `needle` with the single
+/// element in `to_array` for each row in `list_array`.
+///
+/// This is a specialized fast path for the all-scalar case that uses a single
+/// bulk `not_distinct` comparison over only the visible values range, then
+/// iterates match positions via `set_indices` instead of scanning every bit.
+fn general_replace_with_scalar<O: OffsetSizeTrait>(
+    list_array: &GenericListArray<O>,
+    needle: &Scalar<ArrayRef>,
+    scalar_to: &ScalarValue,
+    max_replacements: i64,
+) -> Result<ArrayRef> {
+    // No replacement needed - return unchanged.
+    if max_replacements <= 0 {
+        return Ok(Arc::new(list_array.clone()));
+    }
 
-    // replace at most one occurrence for each element
-    let arr_n = vec![1; array.len()];
-    match array.data_type() {
-        DataType::List(_) => {
-            let list_array = array.as_list::<i32>();
-            general_replace::<i32>(list_array, from, to, &arr_n)
+    let first_offset = list_array.offsets()[0].to_usize().unwrap();
+    let last_offset = list_array.offsets()[list_array.len()].to_usize().unwrap();
+    let visible_values = list_array
+        .values()
+        .slice(first_offset, last_offset - first_offset);
+
+    let to_array = scalar_to.to_array_of_size(1)?;
+    let original_data = visible_values.to_data();
+    let to_data = to_array.to_data();
+    let capacity = Capacities::Array(original_data.len());
+
+    let mut mutable = MutableArrayData::with_capacities(
+        vec![&original_data, &to_data],
+        false,
+        capacity,
+    );
+
+    let mut offsets = OffsetBufferBuilder::<O>::new(list_array.len());
+
+    // Single bulk comparison over the visible values only.
+    let match_bitmap = arrow_ord::cmp::not_distinct(&visible_values, needle)?;
+    let match_bits = match_bitmap.values();
+
+    for (row_index, offset_window) in list_array.offsets().windows(2).enumerate() {
+        // Offsets relative to visible_values (subtract first_offset).
+        let start = offset_window[0].to_usize().unwrap() - first_offset;
+        let end = offset_window[1].to_usize().unwrap() - first_offset;
+        let row_len = end - start;
+
+        if list_array.is_null(row_index) {
+            offsets.push_length(0);
+            continue;
         }
-        DataType::LargeList(_) => {
-            let list_array = array.as_list::<i64>();
-            general_replace::<i64>(list_array, from, to, &arr_n)
+
+        // Slice the match bits to this row and iterate only over true positions.
+        let row_bits = match_bits.slice(start, row_len);
+        let mut match_positions = row_bits
+            .set_indices()
+            .take(max_replacements as usize)
+            .peekable();
+        if match_positions.peek().is_none() {
+            mutable.extend(0, start, end);
+            offsets.push_length(row_len);
+            continue;
         }
-        DataType::Null => Ok(new_null_array(array.data_type(), 1)),
-        array_type => exec_err!("array_replace does not support type '{array_type}'."),
+
+        // Iterate only over the positions that match using set_indices,
+        // which is more efficient than scanning every bit because the number
+        // of matches is typically much smaller than the total array size.
+        let mut prev_end = 0usize;
+        for match_pos in match_positions {
+            // Retain elements before this match.
+            if match_pos > prev_end {
+                mutable.extend(0, start + prev_end, start + match_pos);
+            }
+            // Emit the replacement element.
+            mutable.extend(1, 0, 1);
+            prev_end = match_pos + 1;
+        }
+
+        // Copy remaining elements after the last replacement.
+        if prev_end < row_len {
+            mutable.extend(0, start + prev_end, end);
+        }
+
+        offsets.push_length(row_len);
     }
+
+    let data = mutable.freeze();
+
+    Ok(Arc::new(GenericListArray::<O>::try_new(
+        Arc::new(Field::new_list_field(list_array.value_type(), true)),
+        offsets.finish(),
+        arrow::array::make_array(data),
+        list_array.nulls().cloned(),
+    )?))
 }
 
-fn array_replace_n_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
-    let [array, from, to, max] = take_function_args("array_replace_n", args)?;
+/// Fast path for `array_replace` when all arguments are scalars.
+///
+/// Uses a single bulk `not_distinct` comparison instead of per-row comparisons.
+fn array_replace_with_scalar_args(
+    list_array: &ArrayRef,
+    scalar_from: &ScalarValue,
+    scalar_to: &ScalarValue,
+    max_replacements: i64,
+) -> Result<ArrayRef> {
+    // `not_distinct` doesn't support nested types, fall back to the generic array path.
+    if scalar_from.data_type().is_nested() {
+        let num_rows = list_array.len();
+        let from_array = scalar_from.to_array_of_size(num_rows)?;
+        let to_array = scalar_to.to_array_of_size(num_rows)?;
+        return array_replace_internal(
+            list_array,
+            &from_array,
+            &to_array,
+            &vec![max_replacements; num_rows],
+        );
+    }
 
-    // replace the specified number of occurrences
-    let arr_n = as_int64_array(max)?.values().to_vec();
-    match array.data_type() {
+    let needle = Scalar::new(scalar_from.to_array_of_size(1)?);
+    match list_array.data_type() {
         DataType::List(_) => {
-            let list_array = array.as_list::<i32>();
-            general_replace::<i32>(list_array, from, to, &arr_n)
+            let list = list_array.as_list::<i32>();
+            general_replace_with_scalar::<i32>(list, &needle, scalar_to, max_replacements)
         }
         DataType::LargeList(_) => {
-            let list_array = array.as_list::<i64>();
-            general_replace::<i64>(list_array, from, to, &arr_n)
-        }
-        DataType::Null => Ok(new_null_array(array.data_type(), 1)),
-        array_type => {
-            exec_err!("array_replace_n does not support type '{array_type}'.")
+            let list = list_array.as_list::<i64>();
+            general_replace_with_scalar::<i64>(list, &needle, scalar_to, max_replacements)
         }
+        DataType::Null => Ok(new_null_array(list_array.data_type(), 1)),
+        array_type => exec_err!("array_replace does not support type '{array_type}'."),
     }
 }
 
-fn array_replace_all_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
-    let [array, from, to] = take_function_args("array_replace_all", args)?;
-
-    // replace all occurrences (up to "i64::MAX")
-    let arr_n = vec![i64::MAX; array.len()];
+fn array_replace_internal(
+    array: &ArrayRef,
+    from: &ArrayRef,
+    to: &ArrayRef,
+    arr_n: &[i64],
+) -> Result<ArrayRef> {
     match array.data_type() {
         DataType::List(_) => {
             let list_array = array.as_list::<i32>();
-            general_replace::<i32>(list_array, from, to, &arr_n)
+            general_replace::<i32>(list_array, from, to, arr_n)
         }
         DataType::LargeList(_) => {
             let list_array = array.as_list::<i64>();
-            general_replace::<i64>(list_array, from, to, &arr_n)
+            general_replace::<i64>(list_array, from, to, arr_n)
         }
         DataType::Null => Ok(new_null_array(array.data_type(), 1)),
-        array_type => {
-            exec_err!("array_replace_all does not support type '{array_type}'.")
-        }
+        array_type => exec_err!("array_replace does not support type '{array_type}'."),
     }
 }