diff --git a/crates/examples/Cargo.toml b/crates/examples/Cargo.toml
index cce6faf2..26251cc7 100644
--- a/crates/examples/Cargo.toml
+++ b/crates/examples/Cargo.toml
@@ -37,4 +37,4 @@ path = "src/example_kv_table.rs"
 
 [[example]]
 name = "example-partitioned-upsert-lookup"
-path = "src/example_partitioned_kv_table.rs"
\ No newline at end of file
+path = "src/example_partitioned_kv_table.rs"
diff --git a/crates/fluss/src/metadata/table.rs b/crates/fluss/src/metadata/table.rs
index 7f0d2e2a..dba9a523 100644
--- a/crates/fluss/src/metadata/table.rs
+++ b/crates/fluss/src/metadata/table.rs
@@ -234,8 +234,8 @@ impl SchemaBuilder {
         Ok(self)
     }
 
-    pub fn build(&mut self) -> Result<Schema> {
-        let columns = Self::normalize_columns(&mut self.columns, self.primary_key.as_ref())?;
+    pub fn build(&self) -> Result<Schema> {
+        let columns = Self::normalize_columns(&self.columns, self.primary_key.as_ref())?;
 
         let column_names: HashSet<_> = columns.iter().map(|c| &c.name).collect();
         for auto_inc_col in &self.auto_increment_col_names {
@@ -266,7 +266,7 @@ impl SchemaBuilder {
     }
 
     fn normalize_columns(
-        columns: &mut [Column],
+        columns: &[Column],
         primary_key: Option<&PrimaryKey>,
     ) -> Result<Vec<Column>> {
         let names: Vec<_> = columns.iter().map(|c| &c.name).collect();
diff --git a/crates/fluss/src/test_utils.rs b/crates/fluss/src/test_utils.rs
index 752d4224..47bb2ea8 100644
--- a/crates/fluss/src/test_utils.rs
+++ b/crates/fluss/src/test_utils.rs
@@ -25,7 +25,7 @@ use std::sync::Arc;
 
 pub(crate) fn build_table_info(table_path: TablePath, table_id: i64, buckets: i32) -> TableInfo {
     let row_type = DataTypes::row(vec![DataField::new("id", DataTypes::int(), None)]);
-    let mut schema_builder = Schema::builder().with_row_type(&row_type);
+    let schema_builder = Schema::builder().with_row_type(&row_type);
     let schema = schema_builder.build().expect("schema build");
     let table_descriptor = TableDescriptor::builder()
         .schema(schema)