diff --git a/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.cpp b/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.cpp
index 70beaec5e5e..22df2abecf3 100644
--- a/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.cpp
+++ b/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.cpp
@@ -29,9 +29,6 @@ MergeTreeDataPartWriterCompact::MergeTreeDataPartWriterCompact(
     , marks(*marks_file)
 {
     const auto & storage_columns = metadata_snapshot->getColumns();
-
-    /// Create compressed stream for every different codec.
-    std::unordered_map<UInt64, CompressedStreamPtr> streams_by_codec;
     for (const auto & column : columns_list)
     {
         auto codec = storage_columns.getCodecOrDefault(column.name, default_codec);
@@ -226,7 +223,7 @@ void MergeTreeDataPartWriterCompact::addToChecksums(MergeTreeDataPartChecksums &
     size_t uncompressed_size = 0;
     CityHash_v1_0_2::uint128 uncompressed_hash{0, 0};
 
-    for (const auto & stream : compressed_streams)
+    for (const auto & [_, stream] : streams_by_codec)
     {
         uncompressed_size += stream->hashing_buf.count();
         auto stream_hash = stream->hashing_buf.getHash();
diff --git a/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.h b/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.h
index 2f24c515fb3..a121554f4be 100644
--- a/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.h
+++ b/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.h
@@ -62,6 +62,11 @@ private:
     };
 
     using CompressedStreamPtr = std::shared_ptr<CompressedStream>;
+
+    /// Create compressed stream for every different codec.
+    std::unordered_map<UInt64, CompressedStreamPtr> streams_by_codec;
+
+    /// For better performance save pointer to stream by every column.
     std::vector<CompressedStreamPtr> compressed_streams;
 
     /// marks -> marks_file