diff --git a/cpp-ch/local-engine/Shuffle/PartitionWriter.cpp b/cpp-ch/local-engine/Shuffle/PartitionWriter.cpp
index 3623e493bf48d..20f47d869ec24 100644
--- a/cpp-ch/local-engine/Shuffle/PartitionWriter.cpp
+++ b/cpp-ch/local-engine/Shuffle/PartitionWriter.cpp
@@ -303,7 +303,7 @@ void Partition::clear()
         blocks.clear();
 }
 
-size_t Partition::spill(DB::NativeWriter & writer)
+size_t Partition::spill(NativeWriter & writer)
 {
     std::unique_lock<std::mutex> lock(mtx, std::try_to_lock);
     if (lock.owns_lock())
diff --git a/cpp-ch/local-engine/Shuffle/PartitionWriter.h b/cpp-ch/local-engine/Shuffle/PartitionWriter.h
index a0d83c194b05e..0a457e39415e7 100644
--- a/cpp-ch/local-engine/Shuffle/PartitionWriter.h
+++ b/cpp-ch/local-engine/Shuffle/PartitionWriter.h
@@ -48,7 +48,7 @@ class Partition
     void addBlock(DB::Block & block);
     bool empty() const;
     void clear();
-    size_t spill(DB::NativeWriter & writer);
+    size_t spill(NativeWriter & writer);
 
 private:
     std::vector<DB::Block> blocks;
diff --git a/cpp-ch/local-engine/Storages/IO/AggregateSerializationUtils.cpp b/cpp-ch/local-engine/Storages/IO/AggregateSerializationUtils.cpp
index d53d565c42e72..49b8f274ad2a9 100644
--- a/cpp-ch/local-engine/Storages/IO/AggregateSerializationUtils.cpp
+++ b/cpp-ch/local-engine/Storages/IO/AggregateSerializationUtils.cpp
@@ -19,8 +19,10 @@
 
 #include <Columns/ColumnAggregateFunction.h>
 #include <Columns/ColumnFixedString.h>
+#include <Columns/ColumnString.h>
 #include <DataTypes/DataTypeAggregateFunction.h>
 #include <DataTypes/DataTypeFixedString.h>
+#include <DataTypes/DataTypeString.h>
 
 
 using namespace DB;
@@ -58,6 +60,30 @@ DB::ColumnWithTypeAndName convertAggregateStateToFixedString(DB::ColumnWithTypeA
     }
     return DB::ColumnWithTypeAndName(std::move(res_col), res_type, col.name);
 }
+
+DB::ColumnWithTypeAndName convertAggregateStateToString(DB::ColumnWithTypeAndName col)
+{
+    if (!isAggregateFunction(col.type))
+    {
+        return col;
+    }
+    const auto *aggregate_col = checkAndGetColumn<ColumnAggregateFunction>(*col.column);
+    auto res_type = std::make_shared<DataTypeString>();
+    auto res_col = res_type->createColumn();
+    PaddedPODArray<UInt8> & column_chars = assert_cast<ColumnString &>(*res_col).getChars();
+    column_chars.reserve(aggregate_col->size() * 60);
+    IColumn::Offsets & column_offsets = assert_cast<ColumnString &>(*res_col).getOffsets();
+    auto value_writer = WriteBufferFromVector<PaddedPODArray<UInt8>>(column_chars);
+    column_offsets.reserve(aggregate_col->size());
+    for (const auto & item : aggregate_col->getData())
+    {
+        aggregate_col->getAggregateFunction()->serialize(item, value_writer);
+        writeChar('\0', value_writer);
+        column_offsets.emplace_back(value_writer.count());
+    }
+    return DB::ColumnWithTypeAndName(std::move(res_col), res_type, col.name);
+}
+
 DB::ColumnWithTypeAndName convertFixedStringToAggregateState(DB::ColumnWithTypeAndName col, DB::DataTypePtr type)
 {
     chassert(isAggregateFunction(type));
@@ -90,7 +116,7 @@ DB::Block convertAggregateStateInBlock(DB::Block block)
     ColumnsWithTypeAndName columns;
     for (const auto & item : block.getColumnsWithTypeAndName())
     {
-        columns.emplace_back(convertAggregateStateToFixedString(item));
+        columns.emplace_back(convertAggregateStateToString(item));
     }
     return columns;
 }
diff --git a/cpp-ch/local-engine/Storages/IO/AggregateSerializationUtils.h b/cpp-ch/local-engine/Storages/IO/AggregateSerializationUtils.h
index 62d5127d8a90f..fb9bd4ae5e876 100644
--- a/cpp-ch/local-engine/Storages/IO/AggregateSerializationUtils.h
+++ b/cpp-ch/local-engine/Storages/IO/AggregateSerializationUtils.h
@@ -24,6 +24,8 @@ DB::Block convertAggregateStateInBlock(DB::Block block);
 
 DB::ColumnWithTypeAndName convertAggregateStateToFixedString(DB::ColumnWithTypeAndName col);
 
+DB::ColumnWithTypeAndName convertAggregateStateToString(DB::ColumnWithTypeAndName col);
+
 DB::ColumnWithTypeAndName convertFixedStringToAggregateState(DB::ColumnWithTypeAndName col, DB::DataTypePtr type);
 
 }
diff --git a/cpp-ch/local-engine/Storages/IO/NativeReader.cpp b/cpp-ch/local-engine/Storages/IO/NativeReader.cpp
index f0c47b9b1f5e6..cf6d11f1695f9 100644
--- a/cpp-ch/local-engine/Storages/IO/NativeReader.cpp
+++ b/cpp-ch/local-engine/Storages/IO/NativeReader.cpp
@@ -73,9 +73,10 @@ void NativeReader::readAggData(const DB::DataTypeAggregateFunction & data_type,
         AggregateDataPtr place = arena.alignedAlloc(size_of_state, align_of_state);
 
         agg_function->create(place);
-
-        auto n = istr.read(place, size_of_state);
-        chassert(n == size_of_state);
+//        UInt64 size;
+//        readVarUInt(size, istr);
+        agg_function->deserialize(place, istr);
+        istr.ignore();
         vec.push_back(place);
     }
 }
diff --git a/cpp-ch/local-engine/Storages/IO/NativeWriter.cpp b/cpp-ch/local-engine/Storages/IO/NativeWriter.cpp
index 1c24f4c1a5e2e..fd7d11fd54b6e 100644
--- a/cpp-ch/local-engine/Storages/IO/NativeWriter.cpp
+++ b/cpp-ch/local-engine/Storages/IO/NativeWriter.cpp
@@ -19,6 +19,8 @@
 #include <IO/WriteHelpers.h>
 #include <DataTypes/Serializations/ISerialization.h>
 #include <Columns/ColumnSparse.h>
+#include <Columns/ColumnString.h>
+
 
 using namespace DB;
 
@@ -69,8 +71,9 @@ size_t NativeWriter::write(const DB::Block & block)
         auto original_type = header.safeGetByPosition(i).type;
         /// Type
         String type_name = original_type->getName();
-        if (isAggregateFunction(original_type)
-            && header.safeGetByPosition(i).column->getDataType() != block.safeGetByPosition(i).column->getDataType())
+        bool is_agg_opt = isAggregateFunction(original_type)
+            && header.safeGetByPosition(i).column->getDataType() != block.safeGetByPosition(i).column->getDataType();
+        if (is_agg_opt)
         {
             writeStringBinary(type_name + AGG_STATE_SUFFIX, ostr);
         }
@@ -83,7 +86,18 @@ size_t NativeWriter::write(const DB::Block & block)
         column.column = recursiveRemoveSparse(column.column);
         /// Data
         if (rows)    /// Zero items of data is always represented as zero number of bytes.
-            writeData(*serialization, column.column, ostr, 0, 0);
+        {
+            if (is_agg_opt)
+            {
+                const auto * str_col = static_cast<const ColumnString *>(column.column.get());
+                const PaddedPODArray<UInt8> & column_chars = str_col->getChars();
+                ostr.write(column_chars.raw_data(), str_col->getOffsets().back());
+            }
+            else
+            {
+                writeData(*serialization, column.column, ostr, 0, 0);
+            }
+        }
     }
 
     size_t written_after = ostr.count();