diff --git a/datafusion/spark/src/function/string/format_string.rs b/datafusion/spark/src/function/string/format_string.rs
index 9809456af9a40..adb0eb2f09951 100644
--- a/datafusion/spark/src/function/string/format_string.rs
+++ b/datafusion/spark/src/function/string/format_string.rs
@@ -304,7 +304,7 @@ impl<'a> Formatter<'a> {
                         return exec_err!("No previous argument to reference");
                     };
                     let (spec, rest) =
-                        take_conversion_specifier(rest, p, arg_types[p - 1].clone())?;
+                        take_conversion_specifier(rest, p, &arg_types[p - 1])?;
                     res.push(FormatElement::Format(spec));
                     rem = rest;
                     continue;
@@ -335,7 +335,7 @@ impl<'a> Formatter<'a> {
                 let (spec, rest) = take_conversion_specifier(
                     rest,
                     current_argument_index,
-                    arg_types[current_argument_index - 1].clone(),
+                    &arg_types[current_argument_index - 1],
                 )
                 .map_err(|e| exec_datafusion_err!("{:?}, format string: {:?}", e, fmt))?;
                 res.push(FormatElement::Format(spec));
@@ -582,7 +582,7 @@ impl TryFrom<char> for TimeFormat {
 }
 
 impl ConversionType {
-    pub fn validate(&self, arg_type: DataType) -> Result<()> {
+    pub fn validate(&self, arg_type: &DataType) -> Result<()> {
         match self {
             ConversionType::BooleanLower | ConversionType::BooleanUpper => {
                 if !matches!(arg_type, DataType::Boolean) {
@@ -716,11 +716,11 @@ impl ConversionType {
     }
 }
 
-fn take_conversion_specifier(
-    mut s: &str,
+fn take_conversion_specifier<'a>(
+    mut s: &'a str,
     argument_index: usize,
-    arg_type: DataType,
-) -> Result<(ConversionSpecifier, &str)> {
+    arg_type: &DataType,
+) -> Result<(ConversionSpecifier, &'a str)> {
     let mut spec = ConversionSpecifier {
         argument_index,
         alt_form: false,
@@ -1186,7 +1186,7 @@ impl ConversionSpecifier {
                         | ConversionType::CompactFloatLower
                         | ConversionType::CompactFloatUpper,
                         Some(value),
-                    ) => self.format_decimal(string, value.to_string(), *scale as i64),
+                    ) => self.format_decimal(string, &value.to_string(), *scale as i64),
                     (
                         ConversionType::StringLower | ConversionType::StringUpper,
                         Some(value),
@@ -1212,7 +1212,7 @@ impl ConversionSpecifier {
                         | ConversionType::CompactFloatLower
                         | ConversionType::CompactFloatUpper,
                         Some(value),
-                    ) => self.format_decimal(string, value.to_string(), *scale as i64),
+                    ) => self.format_decimal(string, &value.to_string(), *scale as i64),
                     (
                         ConversionType::StringLower | ConversionType::StringUpper,
                         Some(value),
@@ -1991,12 +1991,7 @@ impl ConversionSpecifier {
         }
     }
 
-    fn format_decimal(
-        &self,
-        writer: &mut String,
-        value: String,
-        scale: i64,
-    ) -> Result<()> {
+    fn format_decimal(&self, writer: &mut String, value: &str, scale: i64) -> Result<()> {
         let mut prefix = String::new();
         let upper = self.conversion_type.is_upper();
 
diff --git a/datafusion/spark/src/function/string/length.rs b/datafusion/spark/src/function/string/length.rs
index 1fa54d000effa..ac6030770fe27 100644
--- a/datafusion/spark/src/function/string/length.rs
+++ b/datafusion/spark/src/function/string/length.rs
@@ -98,33 +98,33 @@ fn spark_length(args: &[ArrayRef]) -> datafusion_common::Result<ArrayRef> {
     match args[0].data_type() {
         DataType::Utf8 => {
             let string_array = args[0].as_string::<i32>();
-            character_length::<_>(string_array)
+            character_length::<_>(&string_array)
         }
         DataType::LargeUtf8 => {
             let string_array = args[0].as_string::<i64>();
-            character_length::<_>(string_array)
+            character_length::<_>(&string_array)
         }
         DataType::Utf8View => {
             let string_array = args[0].as_string_view();
-            character_length::<_>(string_array)
+            character_length::<_>(&string_array)
         }
         DataType::Binary => {
             let binary_array = args[0].as_binary::<i32>();
-            byte_length::<_>(binary_array)
+            byte_length::<_>(&binary_array)
         }
         DataType::LargeBinary => {
             let binary_array = args[0].as_binary::<i64>();
-            byte_length::<_>(binary_array)
+            byte_length::<_>(&binary_array)
         }
         DataType::BinaryView => {
             let binary_array = args[0].as_binary_view();
-            byte_length::<_>(binary_array)
+            byte_length::<_>(&binary_array)
         }
         other => exec_err!("Unsupported data type {other:?} for function `length`"),
     }
 }
 
-fn character_length<'a, V>(array: V) -> datafusion_common::Result<ArrayRef>
+fn character_length<'a, V>(array: &V) -> datafusion_common::Result<ArrayRef>
 where
     V: StringArrayType<'a>,
 {
@@ -169,7 +169,7 @@ where
     Ok(Arc::new(array))
 }
 
-fn byte_length<'a, V>(array: V) -> datafusion_common::Result<ArrayRef>
+fn byte_length<'a, V>(array: &V) -> datafusion_common::Result<ArrayRef>
 where
     V: BinaryArrayType<'a>,
 {
diff --git a/datafusion/spark/src/lib.rs b/datafusion/spark/src/lib.rs
index 5b1fa06cb2c7c..4f3f795add5ec 100644
--- a/datafusion/spark/src/lib.rs
+++ b/datafusion/spark/src/lib.rs
@@ -22,6 +22,9 @@
 #![cfg_attr(docsrs, feature(doc_cfg))]
 // Make cheap clones clear: https://github.com/apache/datafusion/issues/11143
 #![deny(clippy::clone_on_ref_ptr)]
+// https://github.com/apache/datafusion/issues/18503
+#![deny(clippy::needless_pass_by_value)]
+#![cfg_attr(test, allow(clippy::needless_pass_by_value))]
 
 //! Spark Expression packages for [DataFusion].
 //!