perf: improve performance of string replace (#19530)

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- Closes #.

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Use a reusable String buffer instead of allocating a new String for each
row. This optimization achieves 17-32% performance improvement across
different string types and sizes by avoiding per-row allocations.

Benchmark results:
| Benchmark | Array Size | String Length | Baseline (µs) | Optimized
(µs) | Improvement |

|---------------|------------|---------------|---------------|----------------|-------------|
| string_view | 1024 | 32 | 32.53 | 22.32 | 31.4% faster|
| string | 1024 | 32 | 31.89 | 21.49 | 32.6% faster|
| large_string | 1024 | 32 | 31.75 | 22.01 | 30.7% faster|
| string_view | 1024 | 128 | 49.51 | 36.11 | 27.1% faster|
| string | 1024 | 128 | 48.91 | 34.90 | 28.6% faster|
| large_string | 1024 | 128 | 49.78 | 35.42 | 28.8% faster|
| string_view | 4096 | 32 | 133.67 | 95.93 | 28.2% faster|
| string | 4096 | 32 | 131.48 | 91.73 | 30.2% faster|
| large_string | 4096 | 32 | 129.61 | 92.82 | 28.4% faster|
| string_view | 4096 | 128 | 191.50 | 153.74 | 19.7% faster|
| string | 4096 | 128 | 185.27 | 149.37 | 19.4% faster|
| large_string | 4096 | 128 | 187.82 | 154.32 | 17.8% faster|

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Author: viirya

datafusion/functions/Cargo.toml

@@ -210,6 +210,11 @@ harness = false
 name = "repeat"
 required-features = ["string_expressions"]
 
+[[bench]]
+harness = false
+name = "replace"
+required-features = ["string_expressions"]
+
 [[bench]]
 harness = false
 name = "random"

datafusion/functions/benches/replace.rs

@@ -0,0 +1,193 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+extern crate criterion;
+
+use arrow::array::OffsetSizeTrait;
+use arrow::datatypes::{DataType, Field};
+use arrow::util::bench_util::{
+    create_string_array_with_len, create_string_view_array_with_len,
+};
+use criterion::{Criterion, SamplingMode, criterion_group, criterion_main};
+use datafusion_common::DataFusionError;
+use datafusion_common::config::ConfigOptions;
+use datafusion_expr::{ColumnarValue, ScalarFunctionArgs};
+use datafusion_functions::string;
+use std::hint::black_box;
+use std::sync::Arc;
+use std::time::Duration;
+
+fn create_args<O: OffsetSizeTrait>(
+    size: usize,
+    str_len: usize,
+    force_view_types: bool,
+    from_len: usize,
+    to_len: usize,
+) -> Vec<ColumnarValue> {
+    if force_view_types {
+        let string_array =
+            Arc::new(create_string_view_array_with_len(size, 0.1, str_len, false));
+        let from_array = Arc::new(create_string_view_array_with_len(
+            size, 0.1, from_len, false,
+        ));
+        let to_array =
+            Arc::new(create_string_view_array_with_len(size, 0.1, to_len, false));
+        vec![
+            ColumnarValue::Array(string_array),
+            ColumnarValue::Array(from_array),
+            ColumnarValue::Array(to_array),
+        ]
+    } else {
+        let string_array =
+            Arc::new(create_string_array_with_len::<O>(size, 0.1, str_len));
+        let from_array = Arc::new(create_string_array_with_len::<O>(size, 0.1, from_len));
+        let to_array = Arc::new(create_string_array_with_len::<O>(size, 0.1, to_len));
+
+        vec![
+            ColumnarValue::Array(string_array),
+            ColumnarValue::Array(from_array),
+            ColumnarValue::Array(to_array),
+        ]
+    }
+}
+
+fn invoke_replace_with_args(
+    args: Vec<ColumnarValue>,
+    number_rows: usize,
+) -> Result<ColumnarValue, DataFusionError> {
+    let arg_fields = args
+        .iter()
+        .enumerate()
+        .map(|(idx, arg)| Field::new(format!("arg_{idx}"), arg.data_type(), true).into())
+        .collect::<Vec<_>>();
+    let config_options = Arc::new(ConfigOptions::default());
+
+    string::replace().invoke_with_args(ScalarFunctionArgs {
+        args,
+        arg_fields,
+        number_rows,
+        return_field: Field::new("f", DataType::Utf8, true).into(),
+        config_options: Arc::clone(&config_options),
+    })
+}
+
+fn criterion_benchmark(c: &mut Criterion) {
+    for size in [1024, 4096] {
+        let mut group = c.benchmark_group(format!("replace size={size}"));
+        group.sampling_mode(SamplingMode::Flat);
+        group.sample_size(10);
+        group.measurement_time(Duration::from_secs(10));
+
+        // ASCII single character replacement (fast path)
+        let str_len = 32;
+        let args = create_args::<i32>(size, str_len, false, 1, 1);
+        group.bench_function(
+            format!("replace_string_ascii_single [size={size}, str_len={str_len}]"),
+            |b| {
+                b.iter(|| {
+                    let args_cloned = args.clone();
+                    black_box(invoke_replace_with_args(args_cloned, size))
+                })
+            },
+        );
+
+        // Multi-character strings (general path)
+        let args = create_args::<i32>(size, str_len, true, 3, 5);
+        group.bench_function(
+            format!("replace_string_view [size={size}, str_len={str_len}]"),
+            |b| {
+                b.iter(|| {
+                    let args_cloned = args.clone();
+                    black_box(invoke_replace_with_args(args_cloned, size))
+                })
+            },
+        );
+
+        let args = create_args::<i32>(size, str_len, false, 3, 5);
+        group.bench_function(
+            format!("replace_string [size={size}, str_len={str_len}]"),
+            |b| {
+                b.iter(|| {
+                    let args_cloned = args.clone();
+                    black_box(invoke_replace_with_args(args_cloned, size))
+                })
+            },
+        );
+
+        let args = create_args::<i64>(size, str_len, false, 3, 5);
+        group.bench_function(
+            format!("replace_large_string [size={size}, str_len={str_len}]"),
+            |b| {
+                b.iter(|| {
+                    let args_cloned = args.clone();
+                    black_box(invoke_replace_with_args(args_cloned, size))
+                })
+            },
+        );
+
+        // Larger strings
+        let str_len = 128;
+        let args = create_args::<i32>(size, str_len, false, 1, 1);
+        group.bench_function(
+            format!("replace_string_ascii_single [size={size}, str_len={str_len}]"),
+            |b| {
+                b.iter(|| {
+                    let args_cloned = args.clone();
+                    black_box(invoke_replace_with_args(args_cloned, size))
+                })
+            },
+        );
+
+        let args = create_args::<i32>(size, str_len, true, 3, 5);
+        group.bench_function(
+            format!("replace_string_view [size={size}, str_len={str_len}]"),
+            |b| {
+                b.iter(|| {
+                    let args_cloned = args.clone();
+                    black_box(invoke_replace_with_args(args_cloned, size))
+                })
+            },
+        );
+
+        let args = create_args::<i32>(size, str_len, false, 3, 5);
+        group.bench_function(
+            format!("replace_string [size={size}, str_len={str_len}]"),
+            |b| {
+                b.iter(|| {
+                    let args_cloned = args.clone();
+                    black_box(invoke_replace_with_args(args_cloned, size))
+                })
+            },
+        );
+
+        let args = create_args::<i64>(size, str_len, false, 3, 5);
+        group.bench_function(
+            format!("replace_large_string [size={size}, str_len={str_len}]"),
+            |b| {
+                b.iter(|| {
+                    let args_cloned = args.clone();
+                    black_box(invoke_replace_with_args(args_cloned, size))
+                })
+            },
+        );
+
+        group.finish();
+    }
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);

datafusion/functions/src/string/replace.rs

@@ -18,7 +18,7 @@
 use std::any::Any;
 use std::sync::Arc;
 
-use arrow::array::{ArrayRef, GenericStringArray, OffsetSizeTrait, StringArray};
+use arrow::array::{ArrayRef, GenericStringBuilder, OffsetSizeTrait};
 use arrow::datatypes::DataType;
 
 use crate::utils::{make_scalar_function, utf8_to_str_type};
@@ -165,17 +165,25 @@ fn replace_view(args: &[ArrayRef]) -> Result<ArrayRef> {
     let from_array = as_string_view_array(&args[1])?;
     let to_array = as_string_view_array(&args[2])?;
 
-    let result = string_array
+    let mut builder = GenericStringBuilder::<i32>::new();
+    let mut buffer = String::new();
+
+    for ((string, from), to) in string_array
         .iter()
         .zip(from_array.iter())
         .zip(to_array.iter())
-        .map(|((string, from), to)| match (string, from, to) {
-            (Some(string), Some(from), Some(to)) => Some(string.replace(from, to)),
-            _ => None,
-        })
-        .collect::<StringArray>();
+    {
+        match (string, from, to) {
+            (Some(string), Some(from), Some(to)) => {
+                buffer.clear();
+                replace_into_string(&mut buffer, string, from, to);
+                builder.append_value(&buffer);
+            }
+            _ => builder.append_null(),
+        }
+    }
 
-    Ok(Arc::new(result) as ArrayRef)
+    Ok(Arc::new(builder.finish()) as ArrayRef)
 }
 
 /// Replaces all occurrences in string of substring from with substring to.
@@ -185,17 +193,64 @@ fn replace<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
     let from_array = as_generic_string_array::<T>(&args[1])?;
     let to_array = as_generic_string_array::<T>(&args[2])?;
 
-    let result = string_array
+    let mut builder = GenericStringBuilder::<T>::new();
+    let mut buffer = String::new();
+
+    for ((string, from), to) in string_array
         .iter()
         .zip(from_array.iter())
         .zip(to_array.iter())
-        .map(|((string, from), to)| match (string, from, to) {
-            (Some(string), Some(from), Some(to)) => Some(string.replace(from, to)),
-            _ => None,
-        })
-        .collect::<GenericStringArray<T>>();
+    {
+        match (string, from, to) {
+            (Some(string), Some(from), Some(to)) => {
+                buffer.clear();
+                replace_into_string(&mut buffer, string, from, to);
+                builder.append_value(&buffer);
+            }
+            _ => builder.append_null(),
+        }
+    }
 
-    Ok(Arc::new(result) as ArrayRef)
+    Ok(Arc::new(builder.finish()) as ArrayRef)
+}
+
+/// Helper function to perform string replacement into a reusable String buffer
+#[inline]
+fn replace_into_string(buffer: &mut String, string: &str, from: &str, to: &str) {
+    if from.is_empty() {
+        // When from is empty, insert 'to' at the beginning, between each character, and at the end
+        // This matches the behavior of str::replace()
+        buffer.push_str(to);
+        for ch in string.chars() {
+            buffer.push(ch);
+            buffer.push_str(to);
+        }
+        return;
+    }
+
+    // Fast path for replacing a single ASCII character with another single ASCII character
+    // This matches Rust's str::replace() optimization and enables vectorization
+    if let ([from_byte], [to_byte]) = (from.as_bytes(), to.as_bytes())
+        && from_byte.is_ascii()
+        && to_byte.is_ascii()
+    {
+        // SAFETY: We're replacing ASCII with ASCII, which preserves UTF-8 validity
+        let replaced: Vec<u8> = string
+            .as_bytes()
+            .iter()
+            .map(|b| if *b == *from_byte { *to_byte } else { *b })
+            .collect();
+        buffer.push_str(unsafe { std::str::from_utf8_unchecked(&replaced) });
+        return;
+    }
+
+    let mut last_end = 0;
+    for (start, _part) in string.match_indices(from) {
+        buffer.push_str(&string[last_end..start]);
+        buffer.push_str(to);
+        last_end = start + from.len();
+    }
+    buffer.push_str(&string[last_end..]);
 }
 
 #[cfg(test)]