Completing the information of insert into select clause in direct-mode

src/sql/engine/cmd/ob_table_direct_insert_service.h

@@ -12,10 +12,15 @@ namespace sql
 {
 class ObExecContext;
 class ObPhysicalPlan;
+class ObOptimizerContext;
+class ObDMLStmt;
 
 class ObTableDirectInsertService
 {
 public:
+  static int check_direct_insert(ObOptimizerContext &optimizer_ctx,
+                                 const ObDMLStmt &stmt,
+                                 bool &is_direct_insert);
   static bool is_direct_insert(const ObPhysicalPlan &phy_plan);
   // all insert-tasks within an insert into select clause are wrapped by a single direct insert instance
   static int start_direct_insert(ObExecContext &ctx, ObPhysicalPlan &plan);