diff --git a/src/sql/code_generator/ob_static_engine_cg.cpp b/src/sql/code_generator/ob_static_engine_cg.cpp
index 9697b3ec5e..352c6871ff 100644
--- a/src/sql/code_generator/ob_static_engine_cg.cpp
+++ b/src/sql/code_generator/ob_static_engine_cg.cpp
@@ -4154,6 +4154,10 @@ int ObStaticEngineCG::construct_hash_elements_for_connect_by(ObLogJoin &op, ObNL
   } else if (OB_ISNULL(left_op = op.get_child(0)) || OB_ISNULL(right_op = op.get_child(1))) {
     ret = OB_ERR_UNEXPECTED;
     LOG_WARN("child op is null", K(ret));
+  } else if (OB_FAIL(spec.hash_key_exprs_.init(op.get_other_join_conditions().count()))) {
+    LOG_WARN("failed to init hash key exprs", K(ret));
+  } else if (OB_FAIL(spec.hash_probe_exprs_.init(op.get_other_join_conditions().count()))) {
+    LOG_WARN("failed to init hash probe exprs", K(ret));
   } else {
     const ObRelIds &left_table_set = left_op->get_table_set();
     const ObRelIds &right_table_set = right_op->get_table_set();
diff --git a/src/sql/engine/connect_by/ob_cnnt_by_pump.cpp b/src/sql/engine/connect_by/ob_cnnt_by_pump.cpp
index 0e30128890..132f0fe569 100644
--- a/src/sql/engine/connect_by/ob_cnnt_by_pump.cpp
+++ b/src/sql/engine/connect_by/ob_cnnt_by_pump.cpp
@@ -602,17 +602,18 @@ void ObConnectByOpPump::ConnectByHashTable::reverse_bucket_cells()
   }
 }
 
-int ObConnectByOpPump::calc_hash_value(const ObArray<ObExpr *> &hash_exprs, uint64_t &hash_value)
+int ObConnectByOpPump::calc_hash_value(const ExprFixedArray &exprs, uint64_t &hash_value)
 {
   int ret = OB_SUCCESS;
   ObDatum *datum = NULL;
   hash_value = 0;
-  if (OB_ISNULL(eval_ctx_)) {
+  const ObIArray<ObExpr*> *hash_exprs = &exprs;
+  if (OB_ISNULL(hash_exprs) || OB_ISNULL(eval_ctx_)) {
     ret = OB_ERR_UNEXPECTED;
     LOG_WARN("eval ctx is null", K(ret));
   }
-  for (int64_t i = 0; OB_SUCC(ret) && i < hash_exprs.count(); i++) {
-    ObExpr *hash_expr = hash_exprs.at(i);
+  for (int64_t i = 0; OB_SUCC(ret) && i < hash_exprs->count(); i++) {
+    ObExpr *hash_expr = hash_exprs->at(i);
     if (OB_ISNULL(hash_expr)) {
       ret = OB_ERR_UNEXPECTED;
       LOG_WARN("hash probe expr is null", K(ret));
@@ -650,7 +651,7 @@ int ObConnectByOpPump::build_hash_table(ObIAllocator &alloc)
     hash_table_.all_cells_->reuse();
   }
   HashTableCell **bucket_end_cell = NULL;
-  const ObArray<ObExpr *> &hash_key_exprs =
+  const ExprFixedArray &hash_key_exprs =
     (static_cast<const ObNLConnectBySpec &>(connect_by_->get_spec())).hash_key_exprs_;
   if (OB_FAIL(ret)) {
   } else if (OB_UNLIKELY(0 == hash_key_exprs.count()) || OB_ISNULL(eval_ctx_)) {
@@ -731,7 +732,7 @@ int ObConnectByOpPump::build_hash_table(ObIAllocator &alloc)
 }
 
 int ObConnectByOpPump::RowFetcher::init(ObConnectByOpPump &connect_by_pump,
-                                        const ObArray<ObExpr *> &hash_probe_exprs)
+                                        const ExprFixedArray &hash_probe_exprs)
 {
   int ret = OB_SUCCESS;
   use_hash_ = false;
diff --git a/src/sql/engine/connect_by/ob_cnnt_by_pump.h b/src/sql/engine/connect_by/ob_cnnt_by_pump.h
index e5580ed1c3..10a4021c28 100644
--- a/src/sql/engine/connect_by/ob_cnnt_by_pump.h
+++ b/src/sql/engine/connect_by/ob_cnnt_by_pump.h
@@ -165,7 +165,7 @@ private:
     ObChunkDatumStore::Iterator *iterator_;
     HashTableCell *tuple_;
     bool use_hash_;     // tuple is valid if use_hash_
-    int init(ObConnectByOpPump &connect_by_pump, const ObArray<ObExpr *> &hash_probe_exprs);
+    int init(ObConnectByOpPump &connect_by_pump, const ExprFixedArray &hash_probe_exprs);
     int get_next_row(const ObChunkDatumStore::StoredRow *&row);
     int get_next_row(const ObIArray<ObExpr *> &exprs, ObEvalCtx &eval_ctx);
   };
@@ -289,7 +289,7 @@ public:
   int get_top_pump_node(PumpNode *&node);
   int get_sys_path(uint64_t sys_connect_by_path_id, ObString &parent_path);
   int concat_sys_path(uint64_t sys_connect_by_path_id, const ObString &cur_path);
-  int calc_hash_value(const ObArray<ObExpr *> &hash_exprs, uint64_t &hash_value);
+  int calc_hash_value(const ExprFixedArray &exprs, uint64_t &hash_value);
   int build_hash_table(ObIAllocator &alloc);
 
 private:
diff --git a/src/sql/engine/connect_by/ob_nl_cnnt_by_op.h b/src/sql/engine/connect_by/ob_nl_cnnt_by_op.h
index 9a8e26c7d2..c123cc7fc5 100644
--- a/src/sql/engine/connect_by/ob_nl_cnnt_by_op.h
+++ b/src/sql/engine/connect_by/ob_nl_cnnt_by_op.h
@@ -121,10 +121,10 @@ class ObNLConnectBySpec : public ObNLConnectBySpecBase
 {
   OB_UNIS_VERSION_V(1);
 public:
-	common::ObArray<ObExpr *> hash_key_exprs_;
-  common::ObArray<ObExpr *> hash_probe_exprs_;
+	ExprFixedArray hash_key_exprs_;
+  ExprFixedArray hash_probe_exprs_;
   ObNLConnectBySpec(common::ObIAllocator &alloc, const ObPhyOperatorType type)
-  : ObNLConnectBySpecBase(alloc, type), hash_key_exprs_(), hash_probe_exprs_()
+  : ObNLConnectBySpecBase(alloc, type), hash_key_exprs_(alloc), hash_probe_exprs_(alloc)
   {}
 };