diff --git a/src/query/sql/src/planner/optimizer/optimizer.rs b/src/query/sql/src/planner/optimizer/optimizer.rs
index 1ceb3803d1a3..661768d1c5fa 100644
--- a/src/query/sql/src/planner/optimizer/optimizer.rs
+++ b/src/query/sql/src/planner/optimizer/optimizer.rs
@@ -451,7 +451,7 @@ async fn optimize_merge_into(mut opt_ctx: OptimizerContext, plan: Box<MergeInto>
             .table_ctx
             .get_settings()
             .get_enable_distributed_merge_into()?;
-    let mut new_columns_set = plan.columns_set.clone();
+    let new_columns_set = plan.columns_set.clone();
     if change_join_order
         && matches!(plan.merge_type, MergeIntoType::FullOperation)
         && opt_ctx