diff --git a/src/sql/optimizer/ob_log_set.cpp b/src/sql/optimizer/ob_log_set.cpp
index 15a144da66..b5ec84af47 100644
--- a/src/sql/optimizer/ob_log_set.cpp
+++ b/src/sql/optimizer/ob_log_set.cpp
@@ -218,10 +218,10 @@ int ObLogSet::compute_fd_item_set()
   } else if (OB_FAIL(fd_item_set->push_back(fd_item))) {
     LOG_WARN("failed to push back fd item", K(ret));
   } else if ((ObSelectStmt::INTERSECT == set_op_ || ObSelectStmt::EXCEPT == set_op_) &&
-            OB_FAIL(append(*fd_item_set, left_child->get_fd_item_set()))) {
+            OB_FAIL(append_child_fd_item_set(*fd_item_set, left_child->get_fd_item_set()))) {
     LOG_WARN("failed to append fd item set", K(ret));
   } else if (ObSelectStmt::INTERSECT == set_op_ &&
-            OB_FAIL(append(*fd_item_set, right_child->get_fd_item_set()))) {
+            OB_FAIL(append_child_fd_item_set(*fd_item_set, right_child->get_fd_item_set()))) {
     LOG_WARN("failed to append fd item set", K(ret));
   } else if (OB_FAIL(deduce_const_exprs_and_ft_item_set(*fd_item_set))) {
     LOG_WARN("falied to deduce fd item set", K(ret));
@@ -231,6 +231,25 @@ int ObLogSet::compute_fd_item_set()
   return ret;
 }
 
+// just ignore table fd item now
+// todo: adjust log set fd, convert child fd set to currnet level stmt
+int ObLogSet::append_child_fd_item_set(ObFdItemSet &all_fd_item_set, const ObFdItemSet &child_fd_item_set)
+{
+  int ret = OB_SUCCESS;
+  ObFdItem *fd_item = NULL;
+  for (int64_t i = 0; OB_SUCC(ret) && i < child_fd_item_set.count(); ++i) {
+    if (OB_ISNULL(fd_item = child_fd_item_set.at(i))) {
+      ret = OB_ERR_UNEXPECTED;
+      LOG_WARN("get unexpected null", K(ret));
+    } else if (fd_item->is_table_fd_item()) {
+      /* do nothing */
+    } else if (OB_FAIL(all_fd_item_set.push_back(fd_item))) {
+      LOG_WARN("failed to push back fd item", K(ret));
+    }
+  }
+  return ret;
+}
+
 int ObLogSet::compute_op_ordering()
 {
   int ret = OB_SUCCESS;
diff --git a/src/sql/optimizer/ob_log_set.h b/src/sql/optimizer/ob_log_set.h
index c8b23134db..4ecfdfb5d4 100644
--- a/src/sql/optimizer/ob_log_set.h
+++ b/src/sql/optimizer/ob_log_set.h
@@ -121,6 +121,7 @@ public:
   int set_child_ndv(ObIArray<double> &ndv) { return child_ndv_.assign(ndv); }
   int add_child_ndv(double ndv) { return child_ndv_.push_back(ndv); }
   virtual int get_card_without_filter(double &card) override;
+  int append_child_fd_item_set(ObFdItemSet &all_fd_item_set, const ObFdItemSet &child_fd_item_set);
 private:
   bool is_distinct_;
   bool is_recursive_union_;