diff --git a/src/sql/optimizer/ob_logical_operator.cpp b/src/sql/optimizer/ob_logical_operator.cpp
index 29e13676f9..aa3eec17c4 100644
--- a/src/sql/optimizer/ob_logical_operator.cpp
+++ b/src/sql/optimizer/ob_logical_operator.cpp
@@ -1400,6 +1400,8 @@ int ObLogicalOperator::do_pre_traverse_operation(const TraverseOp &op, void *ctx
         LOG_WARN("get unexpected null", K(session), K(ret));
       } else if (is_plan_root() && OB_FAIL(adjust_plan_root_output_exprs())) {
         LOG_WARN("failed to set plan root output", K(ret));
+      } else if (is_plan_root() && OB_FAIL(collecte_inseparable_exprs(*alloc_expr_context))) {
+        LOG_WARN("failed to set plan root output", K(ret));
       } else if (OB_FAIL(allocate_expr_pre(*alloc_expr_context))) {
         LOG_WARN("failed to do allocate expr pre", K(ret));
       } else {
@@ -1686,6 +1688,22 @@ int ObLogicalOperator::mark_expr_produced(ObRawExpr *expr,
   return ret;
 }
 
+int ObLogicalOperator::collecte_inseparable_exprs(ObAllocExprContext &ctx)
+{
+  int ret = OB_SUCCESS;
+  const ObDMLStmt *stmt = NULL;
+  if (OB_ISNULL(stmt = get_stmt())) {
+    ret = OB_ERR_UNEXPECTED;
+    LOG_WARN("get unexpected null", K(stmt), K(ret));
+  } else if (stmt->is_dblink_stmt() && stmt->is_select_stmt()) {
+    const ObSelectStmt *sel_stmt = static_cast<const ObSelectStmt *>(stmt);
+    if (OB_FAIL(sel_stmt->get_select_exprs(ctx.inseparable_exprs_))) {
+      LOG_WARN("failed to get select exprs", K(ret));
+    }
+  }
+  return ret;
+}
+
 int ObLogicalOperator::allocate_expr_pre(ObAllocExprContext &ctx)
 {
   int ret = OB_SUCCESS;
@@ -1880,8 +1898,6 @@ int ObLogicalOperator::add_expr_to_ctx(ObAllocExprContext &ctx,
   if (OB_ISNULL(expr)) {
     ret = OB_ERR_UNEXPECTED;
     LOG_WARN("get unexpected null", K(ret));
-  } else if (log_op_def::LOG_LINK_SCAN == get_type()) {
-    // do not extract shared exprs for link op
   } else if (OB_FAIL(extract_shared_exprs(expr,
                                           ctx,
                                           0,
@@ -2044,11 +2060,13 @@ int ObLogicalOperator::extract_shared_exprs(ObRawExpr *raw_expr,
     LOG_WARN("failed to add var to array", K(ret));
   }
 
-  for (int64_t i = 0; OB_SUCC(ret) && i < raw_expr->get_param_count(); ++i) {
-    ret = SMART_CALL(extract_shared_exprs(raw_expr->get_param_expr(i),
-                                           ctx,
-                                           ref_cnt,
-                                           shard_exprs));
+  if (!ObOptimizerUtil::find_item(ctx.inseparable_exprs_, raw_expr)) {
+    for (int64_t i = 0; OB_SUCC(ret) && i < raw_expr->get_param_count(); ++i) {
+      ret = SMART_CALL(extract_shared_exprs(raw_expr->get_param_expr(i),
+                                            ctx,
+                                            ref_cnt,
+                                            shard_exprs));
+    }
   }
   return ret;
 }
diff --git a/src/sql/optimizer/ob_logical_operator.h b/src/sql/optimizer/ob_logical_operator.h
index 2025d22eda..ba964aad99 100644
--- a/src/sql/optimizer/ob_logical_operator.h
+++ b/src/sql/optimizer/ob_logical_operator.h
@@ -651,6 +651,8 @@ struct ObAllocExprContext
   //  {key => flattern expr, value => reference count }
   hash::ObHashMap<uint64_t, int64_t> flattern_expr_map_;
   common::ObSEArray<ExprProducer, 16, common::ModulePageAllocator, true> expr_producers_;
+  // Exprs that cannot be used to extract shared child exprs
+  common::ObSEArray<ObRawExpr *, 4, common::ModulePageAllocator, true> inseparable_exprs_;
 };
 
 struct ObPxPipeBlockingCtx
@@ -1185,6 +1187,8 @@ public:
     return common::OB_SUCCESS;
   }
 
+  int collecte_inseparable_exprs(ObAllocExprContext &ctx);
+
   virtual int allocate_expr_pre(ObAllocExprContext &ctx);
 
   virtual int get_op_exprs(ObIArray<ObRawExpr*> &all_exprs);
diff --git a/src/sql/rewrite/ob_transform_dblink.cpp b/src/sql/rewrite/ob_transform_dblink.cpp
index 8c824f37cf..064cb70df0 100644
--- a/src/sql/rewrite/ob_transform_dblink.cpp
+++ b/src/sql/rewrite/ob_transform_dblink.cpp
@@ -453,19 +453,6 @@ int ObTransformDBlink::pack_link_table(ObDMLStmt *stmt, bool &trans_happened)
         LOG_TRACE("succeed to pack one link stmt", K(helpers.at(i)));
       }
     }
-  } else if (stmt->is_set_stmt()) {
-    ObSelectStmt *sel_stmt = static_cast<ObSelectStmt *>(stmt);
-    for (int64_t i = 0; OB_SUCC(ret) && i < sel_stmt->get_set_query().count(); ++i) {
-      ObSelectStmt *child_stmt = sel_stmt->get_set_query(i);
-      if (OB_ISNULL(child_stmt)) {
-        ret = OB_ERR_UNEXPECTED;
-        LOG_WARN("unexpected null", K(ret));
-      } else if (!child_stmt->is_dblink_stmt()) {
-        // do nothing
-      } else if (OB_FAIL(ObTransformUtils::pack_stmt(ctx_, static_cast<ObSelectStmt *>(child_stmt)))) {
-        LOG_WARN("failed to pack link stmt", K(ret));
-      }
-    }
   }
   return ret;
 }