diff --git a/src/Interpreters/Aggregator.cpp b/src/Interpreters/Aggregator.cpp
index 6e101005599..e59605890d3 100644
--- a/src/Interpreters/Aggregator.cpp
+++ b/src/Interpreters/Aggregator.cpp
@@ -1951,13 +1951,7 @@ void NO_INLINE Aggregator::convertToBlockImplNotFinal(
     });
 }
 
-
-template <typename Filler>
-Block Aggregator::prepareBlockAndFill(
-    AggregatedDataVariants & data_variants,
-    bool final,
-    size_t rows,
-    Filler && filler) const
+Aggregator::OutputBlockColumns Aggregator::prepareOutputBlockColumns(Arenas & aggregates_pools, bool final, size_t rows) const
 {
     MutableColumns key_columns(params.keys_size);
     MutableColumns aggregate_columns(params.aggregates_size);
@@ -1982,7 +1976,7 @@ Block Aggregator::prepareBlockAndFill(
             /// The ColumnAggregateFunction column captures the shared ownership of the arena with the aggregate function states.
             ColumnAggregateFunction & column_aggregate_func = assert_cast<ColumnAggregateFunction &>(*aggregate_columns[i]);
 
-            for (auto & pool : data_variants.aggregates_pools)
+            for (auto & pool : aggregates_pools)
                 column_aggregate_func.addArena(pool);
 
             aggregate_columns_data[i] = &column_aggregate_func.getData();
@@ -1997,22 +1991,49 @@ Block Aggregator::prepareBlockAndFill(
             {
                 /// The ColumnAggregateFunction column captures the shared ownership of the arena with aggregate function states.
                 if (auto * column_aggregate_func = typeid_cast<ColumnAggregateFunction *>(final_aggregate_columns[i].get()))
-                    for (auto & pool : data_variants.aggregates_pools)
+                    for (auto & pool : aggregates_pools)
                         column_aggregate_func->addArena(pool);
 
                 /// Aggregate state can be wrapped into array if aggregate function ends with -Resample combinator.
-                final_aggregate_columns[i]->forEachSubcolumn([&data_variants](auto & subcolumn)
-                {
-                    if (auto * column_aggregate_func = typeid_cast<ColumnAggregateFunction *>(subcolumn.get()))
-                        for (auto & pool : data_variants.aggregates_pools)
-                            column_aggregate_func->addArena(pool);
-                });
+                final_aggregate_columns[i]->forEachSubcolumn(
+                    [&aggregates_pools](auto & subcolumn)
+                    {
+                        if (auto * column_aggregate_func = typeid_cast<ColumnAggregateFunction *>(subcolumn.get()))
+                            for (auto & pool : aggregates_pools)
+                                column_aggregate_func->addArena(pool);
+                    });
             }
         }
     }
 
+    return {
+        .key_columns = std::move(key_columns),
+        .aggregate_columns = std::move(aggregate_columns),
+        .final_aggregate_columns = std::move(final_aggregate_columns),
+        .aggregate_columns_data = std::move(aggregate_columns_data),
+    };
+}
+
+template <typename Filler>
+Block Aggregator::prepareBlockAndFill(
+    AggregatedDataVariants & data_variants,
+    bool final,
+    size_t rows,
+    Filler && filler) const
+{
+    auto && out_cols = prepareOutputBlockColumns(data_variants.aggregates_pools, final, rows);
+    auto && [key_columns, aggregate_columns, final_aggregate_columns, aggregate_columns_data] = out_cols;
+
     filler(key_columns, aggregate_columns_data, final_aggregate_columns, final);
 
+    return finalizeBlock(std::move(out_cols), final, rows);
+}
+
+Block Aggregator::finalizeBlock(OutputBlockColumns && out_cols, bool final, size_t rows) const
+{
+    auto && [key_columns, aggregate_columns, final_aggregate_columns, aggregate_columns_data] = out_cols;
+
+    Block res_header = getHeader(final);
     Block res = res_header.cloneEmpty();
 
     for (size_t i = 0; i < params.keys_size; ++i)
diff --git a/src/Interpreters/Aggregator.h b/src/Interpreters/Aggregator.h
index 3e8b25c1a8c..6e37c5a63d4 100644
--- a/src/Interpreters/Aggregator.h
+++ b/src/Interpreters/Aggregator.h
@@ -1306,6 +1306,25 @@ private:
         std::vector<IColumn *>  key_columns,
         AggregateColumnsData & aggregate_columns) const;
 
+    struct OutputBlockColumns
+    {
+        /*OutputBlockColumns(size_t keys_size, size_t aggregates_size)
+            : key_columns(keys_size)
+            , aggregate_columns(aggregates_size)
+            , final_aggregate_columns(aggregates_size)
+            , aggregate_columns_data(aggregates_size)
+        {
+        }*/
+
+        MutableColumns key_columns;
+        MutableColumns aggregate_columns;
+        MutableColumns final_aggregate_columns;
+        AggregateColumnsData aggregate_columns_data;
+    };
+
+    OutputBlockColumns prepareOutputBlockColumns(Arenas & aggregates_pools, bool final, size_t rows) const;
+    Block finalizeBlock(OutputBlockColumns && out_cols, bool final, size_t rows) const;
+
     template <typename Filler>
     Block prepareBlockAndFill(
         AggregatedDataVariants & data_variants,