diff --git a/src/observer/mysql/obmp_query.cpp b/src/observer/mysql/obmp_query.cpp
index 3bee30aef3..f90d54faf8 100644
--- a/src/observer/mysql/obmp_query.cpp
+++ b/src/observer/mysql/obmp_query.cpp
@@ -615,6 +615,7 @@ OB_NOINLINE int ObMPQuery::process_with_tmp_context(ObSQLSessionInfo &session,
                      force_sync_resp,
                      async_resp_used,
                      need_disconnect);
+    ctx_.first_plan_hash_ = 0;
     ctx_.first_outline_data_.reset();
     ctx_.clear();
   }
diff --git a/src/sql/rewrite/ob_transform_join_elimination.cpp b/src/sql/rewrite/ob_transform_join_elimination.cpp
index d716feb4b9..e35a38eb03 100644
--- a/src/sql/rewrite/ob_transform_join_elimination.cpp
+++ b/src/sql/rewrite/ob_transform_join_elimination.cpp
@@ -1703,8 +1703,6 @@ int ObTransformJoinElimination::eliminate_semi_join_self_foreign_key(ObDMLStmt *
       if (OB_ISNULL(semi_info = semi_infos.at(i))) {
         ret = OB_ERR_UNEXPECTED;
         LOG_WARN("get unexpected null", K(ret), K(semi_info));
-      } else if (OB_FAIL(preprocess_generate_right_table(*stmt, *semi_info))) {
-        LOG_WARN("failed to preprocess generate right table", K(ret));
       } else if (OB_FAIL(eliminate_semi_join_self_key(stmt,
                                                       semi_info,
                                                       candi_conds,
@@ -1734,23 +1732,6 @@ int ObTransformJoinElimination::eliminate_semi_join_self_foreign_key(ObDMLStmt *
   return ret;
 }
 
-// flatten joined table in right table
-int ObTransformJoinElimination::preprocess_generate_right_table(ObDMLStmt &stmt,
-                                                                SemiInfo &semi_info)
-{
-  int ret = OB_SUCCESS;
-  TableItem *right_table = NULL;
-  if (OB_ISNULL(right_table = stmt.get_table_item_by_id(semi_info.right_table_id_))) {
-    ret = OB_ERR_UNEXPECTED;
-    LOG_WARN("get unexpected null", K(right_table), K(ret));
-  } else if (!right_table->is_generated_table()) {
-    /* do nothing */
-  } else if (OB_FAIL(ObTransformUtils::flatten_joined_table(right_table->ref_query_))) {
-    LOG_WARN("failed to faltten joined table", K(ret));
-  }
-  return ret;
-}
-
 int ObTransformJoinElimination::eliminate_semi_join_self_key(ObDMLStmt *stmt,
                                                              SemiInfo *semi_info,
                                                              ObIArray<ObRawExpr*> &conds,
diff --git a/src/sql/rewrite/ob_transform_join_elimination.h b/src/sql/rewrite/ob_transform_join_elimination.h
index b1a11fe662..b277b5bc49 100644
--- a/src/sql/rewrite/ob_transform_join_elimination.h
+++ b/src/sql/rewrite/ob_transform_join_elimination.h
@@ -431,8 +431,6 @@ private:
 
   int left_join_can_be_eliminated(ObDMLStmt *stmt, TableItem *table, bool &can_be_eliminated);
 
-  int preprocess_generate_right_table(ObDMLStmt &stmt, SemiInfo &semi_info);
-
   int eliminate_semi_join_self_key(ObDMLStmt *stmt,
                                    SemiInfo *semi_info,
                                    ObIArray<ObRawExpr*> &conds,
diff --git a/src/sql/rewrite/ob_transform_predicate_move_around.cpp b/src/sql/rewrite/ob_transform_predicate_move_around.cpp
index 93221c5a80..ebcbc7b1a8 100644
--- a/src/sql/rewrite/ob_transform_predicate_move_around.cpp
+++ b/src/sql/rewrite/ob_transform_predicate_move_around.cpp
@@ -1565,7 +1565,8 @@ int ObTransformPredicateMoveAround::pushdown_into_set_stmt(ObSelectStmt *stmt,
         LOG_WARN("assign preds failed", K(ret));
       } else if (OB_FAIL(append(pushdown_preds, invalid_pushdown_preds))) {
         LOG_WARN("failed to append no push down preds", K(ret));
-      } else if (pushdown_preds.count() != pushdown_preds_cnt
+      } else if ((pushdown_preds.count() != pushdown_preds_cnt
+                 || (stmt->is_set_stmt() && ObOptimizerUtil::find_item(transed_stmts_, stmt)))
                  && OB_FAIL(add_var_to_array_no_dup(transed_stmts_, static_cast<ObDMLStmt*>(parent_stmt)))) {
         LOG_WARN("append transed stmt failed", K(ret));
       } else {/*do nothing*/}