diff --git a/src/observer/mysql/ob_query_driver.cpp b/src/observer/mysql/ob_query_driver.cpp
index e78617038b..cd4f453cfd 100644
--- a/src/observer/mysql/ob_query_driver.cpp
+++ b/src/observer/mysql/ob_query_driver.cpp
@@ -698,8 +698,9 @@ int ObQueryDriver::process_lob_locator_results(ObObj& value,
         LOG_WARN("Lob: handle lob locator v1 failed", K(value), K(GET_MIN_CLUSTER_VERSION()));
       }
     } else { // lob locator v2
+      ObArenaAllocator tmp_alloc("ObLobRead", OB_MALLOC_NORMAL_BLOCK_SIZE, session_info->get_effective_tenant_id());
       ObTextStringIter instr_iter(value);
-      if (OB_FAIL(instr_iter.init(0, session_info, allocator))) {
+      if (OB_FAIL(instr_iter.init(0, session_info, allocator, &tmp_alloc))) {
         LOG_WARN("init lob str inter failed", K(ret), K(value));
       } else if (OB_FAIL(instr_iter.get_full_data(data))) {
         LOG_WARN("Lob: init lob str iter failed ", K(value));
diff --git a/src/share/ob_lob_access_utils.cpp b/src/share/ob_lob_access_utils.cpp
index 490cba1ad4..5bde900211 100644
--- a/src/share/ob_lob_access_utils.cpp
+++ b/src/share/ob_lob_access_utils.cpp
@@ -65,8 +65,8 @@ ObTextStringIter::~ObTextStringIter()
 
 int ObTextStringIter::init(uint32_t buffer_len,
                            const sql::ObBasicSessionInfo *session,
-                           ObIAllocator *allocator,
-                           bool clone_remote /* false */)
+                           ObIAllocator *res_allocator,
+                           ObIAllocator *tmp_allocator)
 {
   int ret = OB_SUCCESS;
   if (is_init_) {
@@ -80,6 +80,7 @@ int ObTextStringIter::init(uint32_t buffer_len,
   } else {
     ObLobLocatorV2 locator(datum_str_, has_lob_header_);
     is_lob_ = true;
+    tmp_alloc_ = tmp_allocator;
     if (!has_lob_header_) {
       is_outrow_ = false;
 
@@ -88,17 +89,18 @@ int ObTextStringIter::init(uint32_t buffer_len,
       COMMON_LOG(WARN,"Lob: invalid lob", K(ret));
     } else if (FALSE_IT(is_outrow_ = !locator.has_inrow_data())) {
     } else if (!is_outrow_) { // inrow lob always get full data, no need ctx_
-    } else if (OB_ISNULL(allocator)) {
+    } else if (OB_ISNULL(res_allocator)) {
       ret = OB_INVALID_ARGUMENT;
       COMMON_LOG(WARN, "Lob: iter with null allocator", K(ret));
     } else { // outrow lob
+      ObIAllocator *allocator = (tmp_allocator == nullptr) ? res_allocator : tmp_allocator;
       char *ctx_buffer = static_cast<char *>(allocator->alloc(sizeof(ObLobTextIterCtx)));
       if (OB_ISNULL(ctx_buffer)) {
         ret = OB_ALLOCATE_MEMORY_FAILED;
         COMMON_LOG(WARN,"Lob: failed to alloc output buffer", K(ret), KP(ctx_buffer));
       } else {
-        ctx_ = new (ctx_buffer) ObLobTextIterCtx(locator, session, allocator, buffer_len);
-        ctx_ ->init(clone_remote);
+        ctx_ = new (ctx_buffer) ObLobTextIterCtx(locator, session, res_allocator, buffer_len);
+        ctx_ ->init();
       }
     }
   }
@@ -194,7 +196,7 @@ int ObTextStringIter::get_outrow_lob_full_data(ObIAllocator *allocator /*nullptr
     COMMON_LOG(WARN, "Lob: get lob manager failed.", K(ret));
   } else { // outrow persist lob
     storage::ObLobAccessParam param;
-    if (OB_SUCC(init_lob_access_param(param, ctx_, cs_type_, allocator))) {
+    if (OB_SUCC(init_lob_access_param(param, ctx_, cs_type_, tmp_alloc_))) {
       param.len_ = (ctx_->total_access_len_ == 0 ? param.byte_size_ : ctx_->total_access_len_);
 
       if (!param.ls_id_.is_valid() || !param.tablet_id_.is_valid()) {
@@ -249,7 +251,7 @@ int ObTextStringIter::get_outrow_prefix_data(uint32_t prefix_char_len)
     COMMON_LOG(WARN, "Lob: get lob manager failed.", K(ret));
   } else { // outrow persist lob
     storage::ObLobAccessParam param;
-    if (OB_SUCC(init_lob_access_param(param, ctx_, cs_type_))) {
+    if (OB_SUCC(init_lob_access_param(param, ctx_, cs_type_, tmp_alloc_))) {
       param.len_ = prefix_char_len;
 
       if (!param.ls_id_.is_valid() || !param.tablet_id_.is_valid()) {
@@ -298,7 +300,7 @@ int ObTextStringIter::get_current_block(ObString &str)
   return ret;
 }
 
-int ObTextStringIter::get_full_data(ObString &data_str, ObIAllocator *allocator)
+int ObTextStringIter::get_full_data(ObString &data_str)
 {
   int ret = OB_SUCCESS;
   if (!is_init_ || state_ != TEXTSTRING_ITER_INIT) {
@@ -316,7 +318,7 @@ int ObTextStringIter::get_full_data(ObString &data_str, ObIAllocator *allocator)
     }
   } else {
     // outrow lob, read full data into a inrow local tmp lob currently
-    if (OB_FAIL(get_outrow_lob_full_data(allocator))) {
+    if (OB_FAIL(get_outrow_lob_full_data())) {
       COMMON_LOG(WARN, "Lob: get lob outrow data failed", K(ret));
     } else {
       data_str.assign_ptr(ctx_->buff_, ctx_->content_byte_len_);
@@ -391,7 +393,7 @@ int ObTextStringIter::get_first_block(ObString &str)
     COMMON_LOG(WARN, "Lob: get lob manager failed.", K(ret));
   } else {
     storage::ObLobAccessParam param;
-    if (OB_SUCC(init_lob_access_param(param, ctx_, cs_type_))) {
+    if (OB_SUCC(init_lob_access_param(param, ctx_, cs_type_, tmp_alloc_))) {
       param.scan_backward_ = ctx_->is_backward_;
       param.offset_ = ctx_->start_offset_;
       param.len_ = (ctx_->total_access_len_ == 0 ? param.byte_size_ : ctx_->total_access_len_);
@@ -830,7 +832,7 @@ int ObTextStringIter::get_char_len(int64_t &char_length)
       COMMON_LOG(WARN, "Lob: get lob manager failed.", K(ret));
     } else {
       storage::ObLobAccessParam param;
-      if (OB_SUCC(init_lob_access_param(param, ctx_, cs_type_))) {
+      if (OB_SUCC(init_lob_access_param(param, ctx_, cs_type_, tmp_alloc_))) {
         uint64_t length = 0;
         if (!param.ls_id_.is_valid() || !param.tablet_id_.is_valid()) {
           ret = OB_INVALID_ARGUMENT;
@@ -911,10 +913,12 @@ int ObTextStringIter::append_outrow_lob_fulldata(ObObj &obj,
         mem_loc_extern->payload_size_ = static_cast<uint32_t>(lob_data_byte_len);
 
         // copy inrow data
+        int64_t tenant_id = (session == nullptr) ? MTL_ID() : session->get_effective_tenant_id();
+        ObArenaAllocator tmp_alloc("ObLobRead", OB_MALLOC_NORMAL_BLOCK_SIZE, tenant_id);
         ObTextStringIterState state;
         ObString src_block_data;
         ObTextStringIter instr_iter(obj);
-        if (OB_FAIL(instr_iter.init(0, session, &allocator))) {
+        if (OB_FAIL(instr_iter.init(0, session, &allocator, &tmp_alloc))) {
           COMMON_LOG(WARN, "Lob: init text string iter failed", K(instr_iter));
         } else {
           while (OB_SUCC(ret)
diff --git a/src/share/ob_lob_access_utils.h b/src/share/ob_lob_access_utils.h
index a132758ae8..01c93511dc 100644
--- a/src/share/ob_lob_access_utils.h
+++ b/src/share/ob_lob_access_utils.h
@@ -116,7 +116,7 @@ public:
                    bool has_lob_header) :
     type_(type), cs_type_(cs_type), is_init_(false), is_lob_(false), is_outrow_(false),
     has_lob_header_(has_lob_header), state_(TEXTSTRING_ITER_INVALID), datum_str_(datum_str),
-    ctx_(nullptr), err_ret_(OB_SUCCESS)
+    ctx_(nullptr), err_ret_(OB_SUCCESS), tmp_alloc_(nullptr)
   {
     if (is_lob_storage(type)) {
       validate_has_lob_header(has_lob_header_);
@@ -126,7 +126,7 @@ public:
   ObTextStringIter(const ObObj &obj) :
     type_(obj.get_type()), cs_type_(obj.get_collation_type()), is_init_(false), is_lob_(false),
     is_outrow_(false), has_lob_header_(obj.has_lob_header()), state_(TEXTSTRING_ITER_INVALID),
-    datum_str_(obj.get_string()), ctx_(nullptr), err_ret_(OB_SUCCESS)
+    datum_str_(obj.get_string()), ctx_(nullptr), err_ret_(OB_SUCCESS), tmp_alloc_(nullptr)
   {
     if (is_lob_storage(obj.get_type())) {
       validate_has_lob_header(has_lob_header_);
@@ -139,14 +139,14 @@ public:
 
   int init(uint32_t buffer_len,
            const sql::ObBasicSessionInfo *session = NULL,
-           ObIAllocator *allocator = NULL,
-           bool clone_remote = false);
+           ObIAllocator *res_allocator = NULL,
+           ObIAllocator *tmp_allocator = NULL);
 
   ObTextStringIterState get_next_block(ObString &str);
 
   int get_current_block(ObString &str);
 
-  int get_full_data(ObString &data_str, ObIAllocator *allocator = nullptr);
+  int get_full_data(ObString &data_str);
 
   int get_inrow_or_outrow_prefix_data(ObString &data_str,
                                       uint32_t prefix_char_len = DEAFULT_LOB_PREFIX_CHAR_LEN);
@@ -207,6 +207,7 @@ private:
   const ObString datum_str_;
   ObLobTextIterCtx *ctx_;
   int err_ret_;
+  ObIAllocator *tmp_alloc_;
 };
 
 // wrapper class to handle templob output(including string types)
diff --git a/src/sql/engine/expr/ob_datum_cast.cpp b/src/sql/engine/expr/ob_datum_cast.cpp
index 614705c5f2..8cd19af8ba 100644
--- a/src/sql/engine/expr/ob_datum_cast.cpp
+++ b/src/sql/engine/expr/ob_datum_cast.cpp
@@ -3851,9 +3851,10 @@ CAST_FUNC_NAME(text, string)
     ObExprStrResAlloc res_alloc(expr, ctx);
     ObTextStringIter instr_iter(in_type, in_cs_type, child_res->get_string(), has_lob_header);
     if (OB_FAIL(instr_iter.init(0, ctx.exec_ctx_.get_my_session(),
-                                is_same_charset ? reinterpret_cast<ObIAllocator *>(&res_alloc) : &temp_allocator))) {
+                                is_same_charset ? reinterpret_cast<ObIAllocator *>(&res_alloc) : &temp_allocator,
+                                &temp_allocator))) {
       LOG_WARN("init lob str iter failed ", K(ret), K(in_type));
-    } else if (OB_FAIL(instr_iter.get_full_data(data, &temp_allocator))) {
+    } else if (OB_FAIL(instr_iter.get_full_data(data))) {
       LOG_WARN("init lob str iter failed ", K(ret), K(in_type));
     } else if (lib::is_oracle_mode()
                && ob_is_clob(in_type, in_cs_type)