diff --git a/src/sql/monitor/ob_sql_plan.cpp b/src/sql/monitor/ob_sql_plan.cpp
index 24e2c82abf..5cffb9df8f 100644
--- a/src/sql/monitor/ob_sql_plan.cpp
+++ b/src/sql/monitor/ob_sql_plan.cpp
@@ -122,6 +122,7 @@ int ObSqlPlan::store_sql_plan_for_explain(ObExecContext *ctx,
   PlanText out_plan_text;
   plan_text.type_ = type;
   ObSEArray<ObSqlPlanItem*, 16> sql_plan_infos;
+  bool allocate_mem_failed = false;
   if (OB_FAIL(init_buffer(plan_text))) {
     LOG_WARN("failed to init buffer", K(ret));
   } else if (OB_FAIL(get_sql_plan_infos(plan_text,
@@ -129,12 +130,14 @@ int ObSqlPlan::store_sql_plan_for_explain(ObExecContext *ctx,
                                         sql_plan_infos))) {
     LOG_WARN("failed to get sql plan infos", K(ret));
   }
+  allocate_mem_failed |= OB_ALLOCATE_MEMORY_FAILED == ret;
   if (OB_FAIL(format_sql_plan(sql_plan_infos,
                               type,
                               option,
                               out_plan_text))) {
     LOG_WARN("failed to format sql plan", K(ret));
   }
+  allocate_mem_failed |= OB_ALLOCATE_MEMORY_FAILED == ret;
   if (OB_FAIL(plan_text_to_strings(out_plan_text, plan_strs))) {
     LOG_WARN("failed to convert plan text to strings", K(ret));
   } else if (OB_FAIL(inner_store_sql_plan_for_explain(ctx,
@@ -147,6 +150,16 @@ int ObSqlPlan::store_sql_plan_for_explain(ObExecContext *ctx,
       ret = OB_SUCCESS;
     }
   }
+  if (OB_SUCC(ret)) {
+    if (allocate_mem_failed) {
+      if (OB_FAIL(plan_strs.push_back("Plan truncated due to insufficient memory!"))) {
+        LOG_WARN("failed to push back string", K(ret));
+      }
+    } else if (plan_strs.empty()) {
+      ret = OB_ERR_UNEXPECTED;
+      LOG_WARN("failed to generate plan", K(ret));
+    }
+  }
   destroy_buffer(plan_text);
   return ret;
 }
diff --git a/src/sql/ob_optimizer_trace_impl.cpp b/src/sql/ob_optimizer_trace_impl.cpp
index 7dca0cfcf2..5caaaeb62b 100644
--- a/src/sql/ob_optimizer_trace_impl.cpp
+++ b/src/sql/ob_optimizer_trace_impl.cpp
@@ -270,8 +270,9 @@ int ObOptimizerTraceImpl::append_lower(const char* msg)
   int ret = OB_SUCCESS;
   char *buf = NULL;
   int64_t buf_len = strlen(msg);
+  common::ObArenaAllocator allocator("OptimizerTrace");
   if (buf_len <= 0) {
-  } else if (OB_ISNULL(buf = static_cast<char*>(allocator_.alloc(buf_len)))) {
+  } else if (OB_ISNULL(buf = static_cast<char*>(allocator.alloc(buf_len)))) {
     ret = OB_ALLOCATE_MEMORY_FAILED;
     LOG_ERROR("Failed to allocate buffer", "buffer size", buf_len, K(ret));
   } else {
diff --git a/src/sql/ob_optimizer_trace_impl.h b/src/sql/ob_optimizer_trace_impl.h
index 853721e670..19c5ba722c 100644
--- a/src/sql/ob_optimizer_trace_impl.h
+++ b/src/sql/ob_optimizer_trace_impl.h
@@ -322,7 +322,8 @@ ObOptimizerTraceImpl::append(const T* expr)
   char *buf = NULL;
   int64_t buf_len = OB_MAX_SQL_LENGTH;
   int64_t pos = 0;
-  if (OB_ISNULL(buf = (char*)allocator_.alloc(buf_len))) {
+  common::ObArenaAllocator allocator("OptimizerTrace");
+  if (OB_ISNULL(buf = (char*)allocator.alloc(buf_len))) {
     ret = OB_ERR_UNEXPECTED;
     //LOG_WARN("failed to alloc buffer", K(ret));
   } else if (OB_NOT_NULL(expr)) {
@@ -346,8 +347,9 @@ ObOptimizerTraceImpl::append(const T* value)
   int ret = OB_SUCCESS;
   ObString sql;
   ObObjPrintParams print_params;
+  common::ObArenaAllocator allocator("OptimizerTrace");
   // TODO: @zhenling, use a valid schema guard in each query
-  if (OB_FAIL(ObSQLUtils::reconstruct_sql(allocator_,
+  if (OB_FAIL(ObSQLUtils::reconstruct_sql(allocator,
                                           value,
                                           sql,
                                           NULL,
diff --git a/src/sql/optimizer/ob_dynamic_sampling.cpp b/src/sql/optimizer/ob_dynamic_sampling.cpp
index a73c51868b..8ae2989ec6 100644
--- a/src/sql/optimizer/ob_dynamic_sampling.cpp
+++ b/src/sql/optimizer/ob_dynamic_sampling.cpp
@@ -520,9 +520,12 @@ int ObDynamicSampling::estimte_rowcount(int64_t max_ds_timeout,
     need_restore_session = true;
   }
   if (OB_SUCC(ret)) {
+    //do not trace dynamic sample sql execute
+    STOP_OPT_TRACE;
     if (OB_FAIL(do_estimate_rowcount(session_info, raw_sql_str))) {
       LOG_WARN("failed to do estimate rowcount", K(ret));
     }
+    RESUME_OPT_TRACE;
   }
   //regardless of whether the above behavior is successful or not, we need to restore session.
   if (need_restore_session) {
diff --git a/src/sql/optimizer/ob_log_plan.cpp b/src/sql/optimizer/ob_log_plan.cpp
index 45daa282de..4305eedda4 100644
--- a/src/sql/optimizer/ob_log_plan.cpp
+++ b/src/sql/optimizer/ob_log_plan.cpp
@@ -3180,6 +3180,8 @@ int ObLogPlan::generate_single_join_level_with_DP(ObIArray<JoinOrderArray> &join
             LOG_TRACE("succeed to generate join order", K(left_tree->get_tables()),
                        K(right_tree->get_tables()), K(is_valid_join), K(abort_type));
           }
+          OPT_TRACE_TIME_USED;
+          OPT_TRACE_MEM_USED;
         }
         OPT_TRACE_END_SECTION;
       }