diff --git a/optd-cost-model/src/memo_ext.rs b/optd-cost-model/src/memo_ext.rs
index 6584319..16cddca 100644
--- a/optd-cost-model/src/memo_ext.rs
+++ b/optd-cost-model/src/memo_ext.rs
@@ -13,8 +13,8 @@ use crate::common::{
 pub trait MemoExt: Send + Sync + 'static {
     /// Get the schema of a group in the memo.
     fn get_schema(&self, group_id: GroupId) -> Schema;
-    /// Get the column reference of a group in the memo.
-    fn get_column_ref(&self, group_id: GroupId) -> GroupAttrRefs;
+    /// Get the attribute reference of a group in the memo.
+    fn get_attribute_ref(&self, group_id: GroupId) -> GroupAttrRefs;
     /// Get the attribute information of a given attribute in a group in the memo.
     fn get_attribute_info(&self, group_id: GroupId, attr_ref_idx: u64) -> Attribute;