diff --git a/src/graph/optimizer/OptGroup.cpp b/src/graph/optimizer/OptGroup.cpp
index 2b68497d229..871513a2704 100644
--- a/src/graph/optimizer/OptGroup.cpp
+++ b/src/graph/optimizer/OptGroup.cpp
@@ -161,6 +161,8 @@ const PlanNode *OptGroup::getPlan() const {
 
 void OptGroup::deleteRefGroupNode(const OptGroupNode *node) {
   groupNodesReferenced_.erase(node);
+#if 0
+  // FIXME(yee): This cleanup will crash the optimizer for LDBC queries, try to fix it next PR
   if (groupNodesReferenced_.empty()) {
     // Cleanup all opt group nodes in current opt group if it's NOT referenced by any other opt
     // group nodes
@@ -168,6 +170,7 @@ void OptGroup::deleteRefGroupNode(const OptGroupNode *node) {
       n->release();
     }
   }
+#endif
 }
 
 OptGroupNode *OptGroupNode::create(OptContext *ctx, PlanNode *node, const OptGroup *group) {
diff --git a/src/graph/optimizer/Optimizer.cpp b/src/graph/optimizer/Optimizer.cpp
index 669c258982f..80793021087 100644
--- a/src/graph/optimizer/Optimizer.cpp
+++ b/src/graph/optimizer/Optimizer.cpp
@@ -128,6 +128,9 @@ void Optimizer::addBodyToGroupNode(OptContext *ctx,
 
 namespace {
 
+// The plan node referenced by argument always is in the left side of plan tree. So we only need to
+// check whether the left root child of binary input plan node contains what the argument needs in
+// its output columns
 bool findArgumentRefPlanNodeInPath(const std::vector<const PlanNode *> &path, PlanNode *argument) {
   DCHECK_EQ(argument->kind(), PlanNode::Kind::kArgument);
   for (int i = path.size() - 1; i >= 0; i--) {