diff --git a/src/query/src/datafusion.rs b/src/query/src/datafusion.rs
index 6f20764e20..e2e577debf 100644
--- a/src/query/src/datafusion.rs
+++ b/src/query/src/datafusion.rs
@@ -354,25 +354,6 @@ impl DatafusionQueryEngine {
         Ok(physical_plan)
     }
 
-    #[tracing::instrument(skip_all)]
-    pub fn optimize(
-        &self,
-        context: &QueryEngineContext,
-        plan: &LogicalPlan,
-    ) -> Result<LogicalPlan> {
-        let _timer = metrics::OPTIMIZE_LOGICAL_ELAPSED.start_timer();
-
-        // Optimized by extension rules
-        let optimized_plan = self
-            .state
-            .optimize_by_extension_rules(plan.clone(), context)?;
-
-        // Optimized by datafusion optimizer
-        let optimized_plan = self.state.session_state().optimize(&optimized_plan)?;
-
-        Ok(optimized_plan)
-    }
-
     #[tracing::instrument(skip_all)]
     fn optimize_physical_plan(
         &self,
diff --git a/src/query/src/planner.rs b/src/query/src/planner.rs
index 0357a210b2..f522dc567a 100644
--- a/src/query/src/planner.rs
+++ b/src/query/src/planner.rs
@@ -419,7 +419,7 @@ impl DfLogicalPlanner {
     ///
     /// This function walks through all expressions in the logical plan,
     /// including subqueries, to identify placeholders and their cast types.
-    pub(crate) fn extract_placeholder_cast_types(
+    fn extract_placeholder_cast_types(
         plan: &LogicalPlan,
     ) -> Result<HashMap<String, Option<DataType>>> {
         let mut placeholder_types = HashMap::new();