diff --git a/ydb/core/tx/columnshard/engines/changes/general_compaction.cpp b/ydb/core/tx/columnshard/engines/changes/general_compaction.cpp
index 631b380e320a..2b47f9b8a736 100644
--- a/ydb/core/tx/columnshard/engines/changes/general_compaction.cpp
+++ b/ydb/core/tx/columnshard/engines/changes/general_compaction.cpp
@@ -275,4 +275,30 @@ std::shared_ptr<TGeneralCompactColumnEngineChanges::IMemoryPredictor> TGeneralCo
     }
 }
 
+ui64 TGeneralCompactColumnEngineChanges::TMemoryPredictorChunkedPolicy::AddPortion(const TPortionInfo& portionInfo) {
+    SumMemoryFix += portionInfo.GetRecordsCount() * (2 * sizeof(ui64) + sizeof(ui32) + sizeof(ui16));
+    ++PortionsCount;
+    THashMap<ui32, ui64> maxChunkSizeByColumn;
+    for (auto&& i : portionInfo.GetRecords()) {
+        SumMemoryFix += i.BlobRange.Size;
+        auto it = maxChunkSizeByColumn.find(i.GetColumnId());
+        if (it == maxChunkSizeByColumn.end()) {
+            maxChunkSizeByColumn.emplace(i.GetColumnId(), i.GetMeta().GetRawBytesVerified());
+        } else {
+            if (it->second < i.GetMeta().GetRawBytesVerified()) {
+                it->second = i.GetMeta().GetRawBytesVerified();
+            }
+        }
+    }
+
+    SumMemoryDelta = 0;
+    for (auto&& i : maxChunkSizeByColumn) {
+        MaxMemoryByColumnChunk[i.first] += i.second;
+        SumMemoryDelta = std::max(SumMemoryDelta, MaxMemoryByColumnChunk[i.first]);
+    }
+
+    AFL_DEBUG(NKikimrServices::TX_COLUMNSHARD)("memory_prediction_after", SumMemoryFix + SumMemoryDelta)("portion_info", portionInfo.DebugString());
+    return SumMemoryFix + SumMemoryDelta;
+}
+
 }
diff --git a/ydb/core/tx/columnshard/engines/changes/general_compaction.h b/ydb/core/tx/columnshard/engines/changes/general_compaction.h
index 506966ac3494..287ba34b37ae 100644
--- a/ydb/core/tx/columnshard/engines/changes/general_compaction.h
+++ b/ydb/core/tx/columnshard/engines/changes/general_compaction.h
@@ -50,27 +50,12 @@ class TGeneralCompactColumnEngineChanges: public TCompactColumnEngineChanges {
 
     class TMemoryPredictorChunkedPolicy: public IMemoryPredictor {
     private:
-        ui64 SumMemory = 0;
+        ui64 SumMemoryDelta = 0;
+        ui64 SumMemoryFix = 0;
         ui32 PortionsCount = 0;
         THashMap<ui32, ui64> MaxMemoryByColumnChunk;
     public:
-        virtual ui64 AddPortion(const TPortionInfo& portionInfo) override {
-            SumMemory += portionInfo.GetRecordsCount() * (2 * sizeof(ui64) + sizeof(ui32) + sizeof(ui16));
-            for (auto&& i : portionInfo.GetRecords()) {
-                SumMemory += i.BlobRange.Size;
-                auto it = MaxMemoryByColumnChunk.find(i.GetColumnId());
-                ++PortionsCount;
-                if (it == MaxMemoryByColumnChunk.end()) {
-                    it = MaxMemoryByColumnChunk.emplace(i.GetColumnId(), i.GetMeta().GetRawBytesVerified()).first;
-                    SumMemory += it->second * PortionsCount;
-                } else if (it->second < i.GetMeta().GetRawBytesVerified()) {
-                    SumMemory -= it->second * (PortionsCount - 1);
-                    it->second = i.GetMeta().GetRawBytesVerified();
-                    SumMemory += it->second * PortionsCount;
-                }
-            }
-            return SumMemory;
-        }
+        virtual ui64 AddPortion(const TPortionInfo& portionInfo) override;
     };
 
     static std::shared_ptr<IMemoryPredictor> BuildMemoryPredictor();