diff --git a/ydb/core/kqp/executer_actor/kqp_executer_stats.cpp b/ydb/core/kqp/executer_actor/kqp_executer_stats.cpp
index 10026e5321da..60dae26fb9df 100644
--- a/ydb/core/kqp/executer_actor/kqp_executer_stats.cpp
+++ b/ydb/core/kqp/executer_actor/kqp_executer_stats.cpp
@@ -836,7 +836,10 @@ void TQueryExecutionStats::AddComputeActorStats(ui32 /* nodeId */, NYql::NDqProt
         // TODO(ilezhankin): investigate - for some reason `task.FinishTimeMs` may be large (or small?)
         //      enough to result in an enormous duration - triggering the "long tasks" mode.
 
-        auto taskDuration = TDuration::MilliSeconds(task.GetFinishTimeMs() - task.GetStartTimeMs());
+        auto taskDuration = TDuration::MilliSeconds(
+            task.GetStartTimeMs() != 0 && task.GetFinishTimeMs() >= task.GetStartTimeMs()
+            ? task.GetFinishTimeMs() - task.GetStartTimeMs()
+            : 0);
         auto& longestTaskDuration = LongestTaskDurations[task.GetStageId()];
         if (taskDuration > Max(collectLongTaskStatsTimeout, longestTaskDuration)) {
             CollectStatsByLongTasks = true;
@@ -982,7 +985,10 @@ void TQueryExecutionStats::AddDatashardStats(NYql::NDqProto::TDqComputeActorStat
 
         // checking whether the task is long
 
-        auto taskDuration = TDuration::MilliSeconds(task.GetFinishTimeMs() - task.GetStartTimeMs());
+        auto taskDuration = TDuration::MilliSeconds(
+            task.GetStartTimeMs() != 0 && task.GetFinishTimeMs() >= task.GetStartTimeMs()
+            ? task.GetFinishTimeMs() - task.GetStartTimeMs()
+            : 0);
         auto& longestTaskDuration = LongestTaskDurations[task.GetStageId()];
         if (taskDuration > Max(collectLongTaskStatsTimeout, longestTaskDuration)) {
             CollectStatsByLongTasks = true;
diff --git a/ydb/core/kqp/runtime/kqp_write_actor.cpp b/ydb/core/kqp/runtime/kqp_write_actor.cpp
index 63b47668c87f..fcd1ad539fb9 100644
--- a/ydb/core/kqp/runtime/kqp_write_actor.cpp
+++ b/ydb/core/kqp/runtime/kqp_write_actor.cpp
@@ -2802,7 +2802,7 @@ class TKqpBufferWriteActor :public TActorBootstrapped<TKqpBufferWriteActor>, pub
     void UpdateTracingState(const char* name, NWilson::TTraceId traceId) {
         BufferWriteActorStateSpan = NWilson::TSpan(TWilsonKqp::BufferWriteActorState, std::move(traceId),
             name, NWilson::EFlags::AUTO_END);
-        if (traceId != BufferWriteActorSpan.GetTraceId()) {
+        if (BufferWriteActorStateSpan.GetTraceId() != BufferWriteActorSpan.GetTraceId()) {
             BufferWriteActorStateSpan.Link(BufferWriteActorSpan.GetTraceId());
         }
         for (auto& [_, info] : WriteInfos) {
diff --git a/ydb/core/kqp/runtime/kqp_write_table.cpp b/ydb/core/kqp/runtime/kqp_write_table.cpp
index 36fb6a6eb300..9b4bda13120a 100644
--- a/ydb/core/kqp/runtime/kqp_write_table.cpp
+++ b/ydb/core/kqp/runtime/kqp_write_table.cpp
@@ -245,7 +245,7 @@ class TRowBatch : public IDataBatch {
         for (const auto& row : Rows) {
             AFL_ENSURE(row.size() == Rows.front().size());
             const auto size = EstimateSize(row);
-            SerializedMemory += GetCellHeaderSize() * rows.Size() + size;
+            SerializedMemory += GetCellHeaderSize() * row.size() + size;
             Memory += size;
         }
     }