diff --git a/src/sql/optimizer/ob_log_plan.cpp b/src/sql/optimizer/ob_log_plan.cpp
index 35bf2dc142..3746319cd3 100644
--- a/src/sql/optimizer/ob_log_plan.cpp
+++ b/src/sql/optimizer/ob_log_plan.cpp
@@ -6648,20 +6648,21 @@ int ObLogPlan::init_groupby_helper(const ObIArray<ObRawExpr*> &group_exprs,
   int ret = OB_SUCCESS;
   ObSQLSessionInfo *session_info = NULL;
   ObLogicalOperator *best_plan = NULL;
-  const ObSelectStmt* stmt = NULL;
+  const ObDMLStmt* stmt = NULL;
   ObSEArray<ObRawExpr*, 4> group_rollup_exprs;
   bool push_group = false;
+  groupby_helper.is_scalar_group_by_ = true;
   groupby_helper.force_use_hash_ = get_log_plan_hint().use_hash_aggregate();
   groupby_helper.force_use_merge_ = get_log_plan_hint().use_merge_aggregate();
   if (OB_FAIL(candidates_.get_best_plan(best_plan))) {
     LOG_WARN("failed to get best plan", K(ret));
   } else if (OB_ISNULL(best_plan) ||
-             OB_ISNULL(get_stmt()) ||
-             OB_UNLIKELY(!get_stmt()->is_select_stmt()) ||
-             OB_ISNULL(stmt = static_cast<const ObSelectStmt*>(get_stmt()))) {
+             OB_ISNULL(stmt = get_stmt())) {
     ret = OB_ERR_UNEXPECTED;
     LOG_WARN("get unexpected null", K(ret));
-  } else if (OB_FALSE_IT(groupby_helper.is_scalar_group_by_ = stmt->is_scala_group_by())) {
+  } else if (stmt->is_select_stmt() &&
+             OB_FALSE_IT(groupby_helper.is_scalar_group_by_ =
+                         static_cast<const ObSelectStmt*>(stmt)->is_scala_group_by())) {
   } else if (OB_FAIL(append(group_rollup_exprs, group_exprs)) ||
              OB_FAIL(append(group_rollup_exprs, rollup_exprs))) {
     LOG_WARN("failed to append group rollup exprs", K(ret));