From 20faccecd13d07e03cd17d274b1b7d2187470529 Mon Sep 17 00:00:00 2001
From: nvphungdev <283886185+nvphungdev@users.noreply.github.com>
Date: Sun, 17 May 2026 00:33:17 +0700
Subject: [PATCH] fix: make replace no-op for empty search

---
 datafusion/functions/src/string/replace.rs  | 42 +++++++++++++++++++--
 datafusion/sqllogictest/test_files/expr.slt |  5 +++
 2 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/datafusion/functions/src/string/replace.rs b/datafusion/functions/src/string/replace.rs
index 769727999ea05..7247d9211cf2c 100644
--- a/datafusion/functions/src/string/replace.rs
+++ b/datafusion/functions/src/string/replace.rs
@@ -268,12 +268,9 @@ fn apply_replace<B: BulkNullStringArrayBuilder>(
     }
 
     if from.is_empty() {
-        // Empty `from`: insert `to` before each character and at both ends.
         builder.append_with(|w| {
-            w.write_str(to);
             for ch in string.chars() {
                 w.write_char(ch);
-                w.write_str(to);
             }
         });
         return;
@@ -316,6 +313,19 @@ mod tests {
             StringArray
         );
 
+        test_function!(
+            ReplaceFunc::new(),
+            vec![
+                ColumnarValue::Scalar(ScalarValue::Utf8(Some(String::from("abc")))),
+                ColumnarValue::Scalar(ScalarValue::Utf8(Some(String::new()))),
+                ColumnarValue::Scalar(ScalarValue::Utf8(Some(String::from("x")))),
+            ],
+            Ok(Some("abc")),
+            &str,
+            Utf8,
+            StringArray
+        );
+
         test_function!(
             ReplaceFunc::new(),
             vec![
@@ -331,6 +341,19 @@ mod tests {
             LargeStringArray
         );
 
+        test_function!(
+            ReplaceFunc::new(),
+            vec![
+                ColumnarValue::Scalar(ScalarValue::LargeUtf8(Some(String::from("abc")))),
+                ColumnarValue::Scalar(ScalarValue::LargeUtf8(Some(String::new()))),
+                ColumnarValue::Scalar(ScalarValue::LargeUtf8(Some(String::from("x")))),
+            ],
+            Ok(Some("abc")),
+            &str,
+            LargeUtf8,
+            LargeStringArray
+        );
+
         test_function!(
             ReplaceFunc::new(),
             vec![
@@ -346,6 +369,19 @@ mod tests {
             StringArray
         );
 
+        test_function!(
+            ReplaceFunc::new(),
+            vec![
+                ColumnarValue::Scalar(ScalarValue::Utf8View(Some(String::from("abc")))),
+                ColumnarValue::Scalar(ScalarValue::Utf8View(Some(String::new()))),
+                ColumnarValue::Scalar(ScalarValue::Utf8View(Some(String::from("x")))),
+            ],
+            Ok(Some("abc")),
+            &str,
+            Utf8,
+            StringArray
+        );
+
         Ok(())
     }
 }
diff --git a/datafusion/sqllogictest/test_files/expr.slt b/datafusion/sqllogictest/test_files/expr.slt
index 163730baae9e8..71d4b16526849 100644
--- a/datafusion/sqllogictest/test_files/expr.slt
+++ b/datafusion/sqllogictest/test_files/expr.slt
@@ -636,6 +636,11 @@ SELECT replace('abcdefabcdef', 'notmatch', 'XX')
 ----
 abcdefabcdef
 
+query T
+SELECT replace('abc', '', 'x')
+----
+abc
+
 query T
 SELECT replace('abcdefabcdef', NULL, 'XX')
 ----