diff --git a/dbms/src/Storages/MergeTree/IMergeTreeDataPartWriter.cpp b/dbms/src/Storages/MergeTree/IMergeTreeDataPartWriter.cpp
index 1605beadeaf..2cad6ee1930 100644
--- a/dbms/src/Storages/MergeTree/IMergeTreeDataPartWriter.cpp
+++ b/dbms/src/Storages/MergeTree/IMergeTreeDataPartWriter.cpp
@@ -90,7 +90,7 @@ IMergeTreeDataPartWriter::IMergeTreeDataPartWriter(
 
 IMergeTreeDataPartWriter::~IMergeTreeDataPartWriter() = default;
 
-void fillIndexGranularityImpl(
+static void fillIndexGranularityImpl(
     const Block & block,
     size_t index_granularity_bytes,
     size_t fixed_index_granularity_rows,
@@ -98,7 +98,7 @@ void fillIndexGranularityImpl(
     size_t index_offset,
     MergeTreeIndexGranularity & index_granularity,
     bool can_use_adaptive_index_granularity,
-    bool need_finish_last_granule)
+    bool need_finish_last_granule = false)
 {
     /// FIXME correct index granularity for compact
     size_t rows_in_block = block.rows();
@@ -151,9 +151,6 @@ void fillIndexGranularityImpl(
         else
             index_granularity.appendMark(index_granularity_for_block);
     }
-
-    for (size_t i = 0; i < index_granularity.getMarksCount(); ++i)
-        std::cerr << "marks: " << index_granularity.getMarkRows(i) << "\n";
 }
 
 void IMergeTreeDataPartWriter::fillIndexGranularity(const Block & block)
@@ -226,7 +223,6 @@ void IMergeTreeDataPartWriter::calculateAndSerializePrimaryIndex(const Block & p
 
     /// Write index. The index contains Primary Key value for each `index_granularity` row.
 
-    std::cerr << "writing index...\n";
     for (size_t i = index_offset; i < rows;)
     {
         if (storage.hasPrimaryKey())
@@ -239,10 +235,6 @@ void IMergeTreeDataPartWriter::calculateAndSerializePrimaryIndex(const Block & p
             }
         }
 
-        std::cerr << "(index) i: " << i << "\n";
-        std::cerr << "(index) current_mark: " << current_mark << "\n";
-        std::cerr << "(index) rows in mark: " << index_granularity.getMarkRows(current_mark) << "\n";
-
         i += index_granularity.getMarkRows(current_mark++);
         if (current_mark >= index_granularity.getMarksCount())
             break;
@@ -322,8 +314,6 @@ void IMergeTreeDataPartWriter::calculateAndSerializeSkipIndices(
 
 void IMergeTreeDataPartWriter::finishPrimaryIndexSerialization(MergeTreeData::DataPart::Checksums & checksums)
 {
-    std::cerr << "finishPrimaryIndexSerialization called...\n";
-
     bool write_final_mark = (with_final_mark && data_written);
     if (write_final_mark && compute_granularity)
         index_granularity.appendMark(0);
@@ -341,9 +331,6 @@ void IMergeTreeDataPartWriter::finishPrimaryIndexSerialization(MergeTreeData::Da
             last_index_row.clear();
         }
 
-
-        std::cerr << "(finishPrimaryIndexSerialization) marks_count: " << index_granularity.getMarksCount() << "\n";
-
         index_stream->next();
         checksums.files["primary.idx"].file_size = index_stream->count();
         checksums.files["primary.idx"].file_hash = index_stream->getHash();
diff --git a/dbms/src/Storages/MergeTree/IMergeTreeDataPartWriter.h b/dbms/src/Storages/MergeTree/IMergeTreeDataPartWriter.h
index 645a44f8238..96c5b7807e1 100644
--- a/dbms/src/Storages/MergeTree/IMergeTreeDataPartWriter.h
+++ b/dbms/src/Storages/MergeTree/IMergeTreeDataPartWriter.h
@@ -94,12 +94,14 @@ public:
 
     const MergeTreeData::ColumnSizeByName & getColumnsSizes() const { return columns_sizes; }
 
-    void setOffsetColumns(WrittenOffsetColumns * written_offset_columns_, bool skip_offsets_)
+    void setWrittenOffsetColumns(WrittenOffsetColumns * written_offset_columns_)
     {
         written_offset_columns = written_offset_columns_;
-        skip_offsets = skip_offsets_;
     }
 
+    using SkipIndices = std::vector<MergeTreeIndexPtr>;
+    const SkipIndices & getSkipIndices() { return skip_indices; }
+
     void initSkipIndices();
     void initPrimaryIndex();
 
@@ -160,8 +162,6 @@ protected:
 
     /// To correctly write Nested elements column-by-column.
     WrittenOffsetColumns * written_offset_columns = nullptr;
-    bool skip_offsets = false;
-
 };
 
 }
diff --git a/dbms/src/Storages/MergeTree/MergeTreeBaseSelectProcessor.cpp b/dbms/src/Storages/MergeTree/MergeTreeBaseSelectProcessor.cpp
index 47d9d89a2c9..b7ee14d141c 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeBaseSelectProcessor.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeBaseSelectProcessor.cpp
@@ -155,8 +155,6 @@ Chunk MergeTreeBaseSelectProcessor::readFromPartImpl()
     UInt64 recommended_rows = estimateNumRows(*task, task->range_reader);
     UInt64 rows_to_read = std::max(UInt64(1), std::min(current_max_block_size_rows, recommended_rows));
 
-    // std::cerr << "(readFromPartImpl) rows_to_read: " << rows_to_read << "\n";
-
     auto read_result = task->range_reader.read(rows_to_read, task->mark_ranges);
 
     /// All rows were filtered. Repeat.
diff --git a/dbms/src/Storages/MergeTree/MergeTreeData.cpp b/dbms/src/Storages/MergeTree/MergeTreeData.cpp
index f8e1147cadd..79acbd5a683 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeData.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeData.cpp
@@ -296,16 +296,13 @@ void MergeTreeData::setProperties(
 
     Names new_primary_key_columns;
     Names new_sorting_key_columns;
-    NameSet sorting_key_columns_set;
+    NameSet primary_key_columns_set;
 
     for (size_t i = 0; i < sorting_key_size; ++i)
     {
         String sorting_key_column = new_sorting_key_expr_list->children[i]->getColumnName();
         new_sorting_key_columns.push_back(sorting_key_column);
 
-        if (!sorting_key_columns_set.emplace(sorting_key_column).second)
-            throw Exception("Sorting key contains duplicate columns", ErrorCodes::BAD_ARGUMENTS);
-
         if (i < primary_key_size)
         {
             String pk_column = new_primary_key_expr_list->children[i]->getColumnName();
@@ -314,6 +311,9 @@ void MergeTreeData::setProperties(
                     + toString(i) + " its column is " + pk_column + ", not " + sorting_key_column,
                     ErrorCodes::BAD_ARGUMENTS);
 
+            if (!primary_key_columns_set.emplace(pk_column).second)
+                throw Exception("Primary key contains duplicate columns", ErrorCodes::BAD_ARGUMENTS);
+
             new_primary_key_columns.push_back(pk_column);
         }
     }
@@ -840,8 +840,6 @@ void MergeTreeData::loadDataParts(bool skip_sanity_checks)
             const auto & part_name = part_names_with_disks[i].first;
             const auto part_disk_ptr = part_names_with_disks[i].second;
 
-            std::cerr << "(loadDataParts) loading part: " << part_name << "\n";
-
             MergeTreePartInfo part_info;
             if (!MergeTreePartInfo::tryParsePartName(part_name, &part_info, format_version))
                 return;
@@ -1678,7 +1676,6 @@ void MergeTreeData::alterDataPart(
     /// Apply the expression and write the result to temporary files.
     if (res.expression)
     {
-        std::cerr << "(alterDataPart) expression: " << res.expression->dumpActions() << "\n";
         BlockInputStreamPtr part_in = std::make_shared<MergeTreeSequentialBlockInputStream>(
                 *this, part, res.expression->getRequiredColumns(), false, /* take_column_types_from_storage = */ false);
 
@@ -1687,8 +1684,6 @@ void MergeTreeData::alterDataPart(
             static_cast<double>(part->bytes_on_disk) / this->getTotalActiveSizeInBytes());
         ExpressionBlockInputStream in(part_in, res.expression);
 
-        std::cerr << "im.header: " << in.getHeader().dumpStructure() << "\n";
-
         /** Don't write offsets for arrays, because ALTER never change them
          *  (MODIFY COLUMN could only change types of elements but never modify array sizes).
           * Also note that they does not participate in 'rename_map'.
@@ -1696,7 +1691,6 @@ void MergeTreeData::alterDataPart(
           *  temporary column name ('converting_column_name') created in 'createConvertExpression' method
           *  will have old name of shared offsets for arrays.
           */
-        IMergedBlockOutputStream::WrittenOffsetColumns unused_written_offsets;
 
         MergedColumnOnlyOutputStream out(
             part,
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataMergerMutator.cpp b/dbms/src/Storages/MergeTree/MergeTreeDataMergerMutator.cpp
index 5ef367ba2fb..ba025f3fa82 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataMergerMutator.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataMergerMutator.cpp
@@ -668,7 +668,7 @@ MergeTreeData::MutableDataPartPtr MergeTreeDataMergerMutator::mergePartsToTempor
     }
 
     MergeStageProgress horizontal_stage_progress(
-        column_sizes ? 1.0 : column_sizes->keyColumnsWeight());
+        column_sizes ? column_sizes->keyColumnsWeight() : 1.0);
 
     for (const auto & part : parts)
     {
@@ -963,8 +963,6 @@ MergeTreeData::MutableDataPartPtr MergeTreeDataMergerMutator::mutatePartToTempor
     if (isCompactPart(source_part))
         commands_for_part.additional_columns = source_part->columns.getNames();
 
-    MutationsInterpreter mutations_interpreter(storage_from_source_part, commands_for_part, context_for_reading, true);
-
     if (!isStorageTouchedByMutations(storage_from_source_part, commands_for_part, context_for_reading))
     {
         LOG_TRACE(log, "Part " << source_part->name << " doesn't change up to mutation version " << future_part.part_info.mutation);
@@ -973,6 +971,7 @@ MergeTreeData::MutableDataPartPtr MergeTreeDataMergerMutator::mutatePartToTempor
     else
         LOG_TRACE(log, "Mutating part " << source_part->name << " to mutation version " << future_part.part_info.mutation);
 
+    MutationsInterpreter mutations_interpreter(storage_from_source_part, commands_for_part, context_for_reading, true);
     auto in = mutations_interpreter.execute(table_lock_holder);
     const auto & updated_header = mutations_interpreter.getUpdatedHeader();
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataPartCompact.cpp b/dbms/src/Storages/MergeTree/MergeTreeDataPartCompact.cpp
index 0008bc23e7a..0977d18b6f8 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataPartCompact.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataPartCompact.cpp
@@ -185,10 +185,6 @@ void MergeTreeDataPartCompact::loadIndexGranularity()
         buffer.seek(columns.size() * sizeof(MarkInCompressedFile), SEEK_CUR);
     }
 
-    std::cerr << "(loadIndexGranularity) marks: " << index_granularity.getMarksCount() << "\n";
-    std::cerr << "(loadIndexGranularity) mark size: " << index_granularity_info.mark_size_in_bytes << "\n";
-    std::cerr << "(loadIndexGranularity) marks file size: " << marks_file_size << "\n";
-
     if (index_granularity.getMarksCount() * index_granularity_info.mark_size_in_bytes != marks_file_size)
         throw Exception("Cannot read all marks from file " + marks_file_path, ErrorCodes::CANNOT_READ_ALL_DATA);
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataPartWide.cpp b/dbms/src/Storages/MergeTree/MergeTreeDataPartWide.cpp
index bc5e8924242..d8c705a874c 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataPartWide.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataPartWide.cpp
@@ -181,7 +181,7 @@ void MergeTreeDataPartWide::loadIndexGranularity()
         throw Exception("No columns in part " + name, ErrorCodes::NO_FILE_IN_DATA_PART);
 
     /// We can use any column, it doesn't matter
-    std::string marks_file_path = index_granularity_info.getMarksFilePath(full_path + escapeForFileName(columns.front().name));
+    std::string marks_file_path = index_granularity_info.getMarksFilePath(full_path + getFileNameForColumn(columns.front()));
     if (!Poco::File(marks_file_path).exists())
         throw Exception("Marks file '" + marks_file_path + "' doesn't exist", ErrorCodes::NO_FILE_IN_DATA_PART);
 
@@ -431,7 +431,8 @@ NameToNameMap MergeTreeDataPartWide::createRenameMapForAlter(
 String MergeTreeDataPartWide::getFileNameForColumn(const NameAndTypePair & column) const
 {
     String filename;
-    column.type->enumerateStreams([&](const IDataType::SubstreamPath & substream_path) {
+    column.type->enumerateStreams([&](const IDataType::SubstreamPath & substream_path)
+    {
         if (filename.empty())
             filename = IDataType::getFileNameForStream(column.name, substream_path);
     });
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataPartWide.h b/dbms/src/Storages/MergeTree/MergeTreeDataPartWide.h
index 8eb572a6d36..ae747382dba 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataPartWide.h
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataPartWide.h
@@ -33,7 +33,7 @@ public:
     using Checksums = MergeTreeDataPartChecksums;
     using Checksum = MergeTreeDataPartChecksums::Checksum;
 
-   MergeTreeDataPartWide(
+    MergeTreeDataPartWide(
         const MergeTreeData & storage_,
         const String & name_,
         const MergeTreePartInfo & info_,
@@ -86,7 +86,7 @@ public:
 
     ~MergeTreeDataPartWide() override;
 
-   bool hasColumnFiles(const String & column, const IDataType & type) const override;
+    bool hasColumnFiles(const String & column, const IDataType & type) const override;
 
 protected:
     void checkConsistency(bool require_part_metadata) const override;
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.cpp b/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.cpp
index fa9d1e279f0..d46d556d7b9 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterCompact.cpp
@@ -40,8 +40,6 @@ void MergeTreeDataPartWriterCompact::write(
     const Block & block, const IColumn::Permutation * permutation,
     const Block & primary_key_block, const Block & skip_indexes_block)
 {
-    std::cerr << "(MergeTreeDataPartWriterCompact::write) block111: " << block.dumpStructure() << "\n";
-
     /// Fill index granularity for this block
     /// if it's unknown (in case of insert data or horizontal merge,
     /// but not in case of vertical merge)
@@ -117,10 +115,6 @@ void MergeTreeDataPartWriterCompact::writeBlock(const Block & block)
 
 size_t MergeTreeDataPartWriterCompact::writeColumnSingleGranule(const ColumnWithTypeAndName & column, size_t from_row, size_t number_of_rows)
 {
-    std::cerr << "(writeColumnSingleGranule) writing column: " << column.name << "\n";
-    std::cerr << "(writeColumnSingleGranule) from_row: " << from_row << "\n";
-    std::cerr << "(writeColumnSingleGranule) number_of_rows: " << number_of_rows << "\n";
-
     size_t old_uncompressed_size = stream->compressed.count();
 
     writeIntBinary(stream->plain_hashing.count(), stream->marks);
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterWide.cpp b/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterWide.cpp
index b3d06bb946f..92c21e3166f 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterWide.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterWide.cpp
@@ -20,7 +20,6 @@ MergeTreeDataPartWriterWide::MergeTreeDataPartWriterWide(
     : IMergeTreeDataPartWriter(part_path_,
         storage_, columns_list_, indices_to_recalc_,
         marks_file_extension_, default_codec_, settings_, index_granularity_, false)
-    , can_use_adaptive_granularity(storage_.canUseAdaptiveGranularity())
 {
     const auto & columns = storage.getColumns();
     for (const auto & it : columns_list)
@@ -35,11 +34,10 @@ void MergeTreeDataPartWriterWide::addStreams(
 {
     IDataType::StreamCallback callback = [&] (const IDataType::SubstreamPath & substream_path)
     {
-        if (skip_offsets && !substream_path.empty() && substream_path.back().type == IDataType::Substream::ArraySizes)
+        if (settings.skip_offsets && !substream_path.empty() && substream_path.back().type == IDataType::Substream::ArraySizes)
             return;
 
         String stream_name = IDataType::getFileNameForStream(name, substream_path);
-
         /// Shared offsets for Nested type.
         if (column_streams.count(stream_name))
             return;
@@ -54,8 +52,6 @@ void MergeTreeDataPartWriterWide::addStreams(
             settings.aio_threshold);
     };
 
-    std::cerr << "(addStreams) name: " << name << "\n";
-
     IDataType::SubstreamPath stream_path;
     type.enumerateStreams(callback, stream_path);
 }
@@ -67,7 +63,7 @@ IDataType::OutputStreamGetter MergeTreeDataPartWriterWide::createStreamGetter(
     return [&, this] (const IDataType::SubstreamPath & substream_path) -> WriteBuffer *
     {
         bool is_offsets = !substream_path.empty() && substream_path.back().type == IDataType::Substream::ArraySizes;
-        if (is_offsets && skip_offsets)
+        if (is_offsets && settings.skip_offsets)
             return nullptr;
 
         String stream_name = IDataType::getFileNameForStream(name, substream_path);
@@ -104,9 +100,6 @@ void MergeTreeDataPartWriterWide::write(const Block & block,
     if (compute_granularity)
         fillIndexGranularity(block);
 
-    std::cerr << "(MergeTreeDataPartWriterWide::write) marks_count: " << index_granularity.getMarksCount() << "\n";
-    std::cerr << "(MergeTreeDataPartWriterWide::write) current_mark: " << current_mark << "\n";
-
     auto offset_columns = written_offset_columns ? *written_offset_columns : WrittenOffsetColumns{};
 
     auto it = columns_list.begin();
@@ -150,7 +143,7 @@ void MergeTreeDataPartWriterWide::writeSingleMark(
      type.enumerateStreams([&] (const IDataType::SubstreamPath & substream_path)
      {
          bool is_offsets = !substream_path.empty() && substream_path.back().type == IDataType::Substream::ArraySizes;
-         if (is_offsets && skip_offsets)
+         if (is_offsets && settings.skip_offsets)
              return;
 
          String stream_name = IDataType::getFileNameForStream(name, substream_path);
@@ -192,7 +185,7 @@ size_t MergeTreeDataPartWriterWide::writeSingleGranule(
     type.enumerateStreams([&] (const IDataType::SubstreamPath & substream_path)
     {
         bool is_offsets = !substream_path.empty() && substream_path.back().type == IDataType::Substream::ArraySizes;
-        if (is_offsets && skip_offsets)
+        if (is_offsets && settings.skip_offsets)
             return;
 
         String stream_name = IDataType::getFileNameForStream(name, substream_path);
@@ -222,10 +215,6 @@ void MergeTreeDataPartWriterWide::writeColumn(
         type.serializeBinaryBulkStatePrefix(serialize_settings, it->second);
     }
 
-    std::cerr << "(writeColumn) table: " << storage.getTableName() << "\n";
-    std::cerr << "(writeColumn) column: " << name << "\n";
-    std::cerr << "(writeColumn) index_offset: " << index_offset << "\n";
-
     const auto & global_settings = storage.global_context.getSettingsRef();
     IDataType::SerializeBinaryBulkSettings serialize_settings;
     serialize_settings.getter = createStreamGetter(name, offset_columns);
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterWide.h b/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterWide.h
index ad8a91c3ec8..10260fb7a90 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterWide.h
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataPartWriterWide.h
@@ -69,9 +69,7 @@ private:
         size_t estimated_size);
 
     SerializationStates serialization_states;
-    bool can_use_adaptive_granularity;
     ColumnStreams column_streams;
-
 };
 
 }
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp b/dbms/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp
index c23b5b6efc6..8e355e8f55b 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp
@@ -718,12 +718,6 @@ Pipes MergeTreeDataSelectExecutor::spreadMarkRangesAmongStreams(
     const Settings & settings,
     const MergeTreeReaderSettings & reader_settings) const
 {
-    std::cerr << "marks to read: ";
-    for (const auto & part : parts)
-        for (auto range : part.ranges)
-            std::cerr << "(" << range.begin << ", " << range.end << ") ";
-
-
     /// Count marks for each part.
     std::vector<size_t> sum_marks_in_parts(parts.size());
     size_t sum_marks = 0;
diff --git a/dbms/src/Storages/MergeTree/MergeTreeDataWriter.cpp b/dbms/src/Storages/MergeTree/MergeTreeDataWriter.cpp
index 2688879b1c8..86a10b35ca2 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeDataWriter.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeDataWriter.cpp
@@ -190,7 +190,6 @@ BlocksWithPartition MergeTreeDataWriter::splitBlockIntoParts(const Block & block
 MergeTreeData::MutableDataPartPtr MergeTreeDataWriter::writeTempPart(BlockWithPartition & block_with_partition)
 {
     Block & block = block_with_partition.block;
-    // std::cerr << "(MergeTreeDataWriter::writeTempPart) block.rows(): " << block.rows() << "\n";
 
     static const String TMP_PREFIX = "tmp_insert_";
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeIOSettings.h b/dbms/src/Storages/MergeTree/MergeTreeIOSettings.h
index ff2b1362bca..e967c7248b2 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeIOSettings.h
+++ b/dbms/src/Storages/MergeTree/MergeTreeIOSettings.h
@@ -28,6 +28,7 @@ struct MergeTreeWriterSettings
     bool blocks_are_granules_size;
     String filename_suffix = "";
     size_t estimated_size = 0;
+    bool skip_offsets = false;
 };
 }
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeIndexGranularityInfo.h b/dbms/src/Storages/MergeTree/MergeTreeIndexGranularityInfo.h
index a51bed5bf69..d72ef5f7917 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeIndexGranularityInfo.h
+++ b/dbms/src/Storages/MergeTree/MergeTreeIndexGranularityInfo.h
@@ -61,7 +61,7 @@ private:
 };
 
 constexpr inline auto getNonAdaptiveMrkExtension() { return ".mrk"; }
-constexpr inline auto getNonAdaptiveMrkSize() { return sizeof(MarkInCompressedFile) * 2; }
+constexpr inline auto getNonAdaptiveMrkSize() { return sizeof(UInt64) * 2; }
 
 std::string getAdaptiveMrkExtension(MergeTreeDataPartType part_type);
 size_t getAdaptiveMrkSize(MergeTreeDataPartType part_type, size_t columns_num);
diff --git a/dbms/src/Storages/MergeTree/MergeTreeIndexReader.cpp b/dbms/src/Storages/MergeTree/MergeTreeIndexReader.cpp
index 709b370c33d..f3fcf1b6cfe 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeIndexReader.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeIndexReader.cpp
@@ -27,7 +27,6 @@ MergeTreeIndexGranulePtr MergeTreeIndexReader::read()
 {
     auto granule = index->createIndexGranule();
     granule->deserializeBinary(*stream.data_buffer);
-    std::cerr << "(MergeTreeIndexReader) granule.empty(): " << granule->empty() << "\n";
     return granule;
 }
 
diff --git a/dbms/src/Storages/MergeTree/MergeTreeRangeReader.cpp b/dbms/src/Storages/MergeTree/MergeTreeRangeReader.cpp
index 81209fd31dc..2fe557040cb 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeRangeReader.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeRangeReader.cpp
@@ -231,9 +231,6 @@ void MergeTreeRangeReader::ReadResult::addGranule(size_t num_rows_)
 
 void MergeTreeRangeReader::ReadResult::adjustLastGranule()
 {
-    std::cerr << "(adjustLastGranule) num_read_rows: " << num_read_rows << "\n";
-    std::cerr << "(adjustLastGranule) total_rows_per_granule: " << total_rows_per_granule << "\n";
-
     size_t num_rows_to_subtract = total_rows_per_granule - num_read_rows;
 
     if (rows_per_granule.empty())
diff --git a/dbms/src/Storages/MergeTree/MergeTreeReaderCompact.cpp b/dbms/src/Storages/MergeTree/MergeTreeReaderCompact.cpp
index dbe5736597d..95db984ba43 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeReaderCompact.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeReaderCompact.cpp
@@ -55,10 +55,6 @@ MergeTreeReaderCompact::MergeTreeReaderCompact(const MergeTreeData::DataPartPtr
 size_t MergeTreeReaderCompact::readRows(size_t from_mark, bool continue_reading, size_t max_rows_to_read, Columns & res_columns)
 {
     /// FIXME compute correct granularity
-    std::cerr << "(MergeTreeReaderCompact::readRows) max_rows_to_read: " << max_rows_to_read << "\n";
-
-    std::cerr << "(MergeTreeReaderCompact::readRows) from_mark: " << from_mark << "\n";
-    std::cerr << "(MergeTreeReaderCompact::readRows) continue_reading: " << continue_reading << "\n";
 
     if (continue_reading)
         from_mark = next_mark;
@@ -75,7 +71,7 @@ size_t MergeTreeReaderCompact::readRows(size_t from_mark, bool continue_reading,
         {
             if (!column_positions[pos])
                 continue;
-            
+
             auto & [name, type] = *name_and_type;
             bool append = res_columns[pos] != nullptr;
             if (!append)
@@ -115,10 +111,6 @@ size_t MergeTreeReaderCompact::readRows(size_t from_mark, bool continue_reading,
 
         ++from_mark;
         read_rows += rows_to_read;
-
-        std::cerr << "(MergeTreeReaderCompact::readRows) cur mark: " << from_mark << "\n";
-        std::cerr << "(MergeTreeReaderCompact::readRows) read_rows: " << read_rows << "\n";
-        std::cerr << "(MergeTreeReaderCompact::readRows) rows_to_read: " << rows_to_read << "\n";
     }
 
     next_mark = from_mark;
@@ -128,14 +120,9 @@ size_t MergeTreeReaderCompact::readRows(size_t from_mark, bool continue_reading,
 
 
 void MergeTreeReaderCompact::readData(
-    const String & name, const IDataType & type, IColumn & column,
+    const String & /* name */, const IDataType & type, IColumn & column,
     size_t from_mark, size_t column_position, size_t rows_to_read)
 {
-    std::cerr << "(MergeTreeReaderCompact::readData) from_mark: " << from_mark << "\n";
-    std::cerr << "(MergeTreeReaderCompact::readData) column_position: " << column_position << "\n";
-    std::cerr << "(MergeTreeReaderCompact::readData) rows_to_read: " << rows_to_read << "\n";
-    std::cerr << "(MergeTreeReaderCompact::readData) start reading column: " << name << "\n";
-
     /// FIXME seek only if needed
     seekToMark(from_mark, column_position);
 
@@ -147,9 +134,6 @@ void MergeTreeReaderCompact::readData(
     IDataType::DeserializeBinaryBulkStatePtr state;
     type.deserializeBinaryBulkStatePrefix(deserialize_settings, state);
     type.deserializeBinaryBulkWithMultipleStreams(column, rows_to_read, deserialize_settings, state);
-
-    // std::cerr << "(MergeTreeReaderCompact::readData) end reading column rows: " << column.size() << "\n";
-    // std::cerr << "(MergeTreeReaderCompact::readData) end reading column: " << name << "\n";
 }
 
 
@@ -166,9 +150,6 @@ void MergeTreeReaderCompact::initMarksLoader()
         size_t marks_count = data_part->getMarksCount();
         size_t mark_size_in_bytes = data_part->index_granularity_info.mark_size_in_bytes;
 
-        std::cerr << "(initMarksLoader) marks_count: " << marks_count << "\n";
-        std::cerr << "() mark_size_in_bytes: " << mark_size_in_bytes << "\n";
-
         size_t expected_file_size = mark_size_in_bytes * marks_count;
         if (expected_file_size != file_size)
             throw Exception(
@@ -180,8 +161,6 @@ void MergeTreeReaderCompact::initMarksLoader()
 
         auto res = std::make_shared<MarksInCompressedFile>(marks_count * columns_num);
 
-        // std::cerr << "(MergeTreeReaderCompact::loadMarks) marks_count: " << marks_count << "\n";
-
         ReadBufferFromFile buffer(mrk_path, file_size);
         size_t i = 0;
 
@@ -189,14 +168,9 @@ void MergeTreeReaderCompact::initMarksLoader()
         {
             buffer.seek(sizeof(size_t), SEEK_CUR);
             buffer.readStrict(reinterpret_cast<char *>(res->data() + i * columns_num), sizeof(MarkInCompressedFile) * columns_num);
-            // std::cerr << "(MergeTreeReaderCompact::loadMarks) i: " << i << "\n";
-            // std::cerr << "(MergeTreeReaderCompact::loadMarks) buffer pos in file: " << buffer.getPositionInFile() << "\n";
             ++i;
         }
 
-        // std::cerr << "(MergeTreeReaderCompact::loadMarks) file_size: " << file_size << "\n";
-        // std::cerr << "(MergeTreeReaderCompact::loadMarks) correct file size: " << i * mark_size_in_bytes << "\n";
-
         if (i * mark_size_in_bytes != file_size)
             throw Exception("Cannot read all marks from file " + mrk_path, ErrorCodes::CANNOT_READ_ALL_DATA);
 
@@ -211,9 +185,6 @@ void MergeTreeReaderCompact::initMarksLoader()
 void MergeTreeReaderCompact::seekToMark(size_t row_index, size_t column_index)
 {
     MarkInCompressedFile mark = marks_loader.getMark(row_index, column_index);
-
-    std::cerr << "(MergeTreeReaderCompact::seekToMark) mark: (" << mark.offset_in_compressed_file << ", " << mark.offset_in_decompressed_block << "\n";
-
     try
     {
         if (cached_buffer)
diff --git a/dbms/src/Storages/MergeTree/MergeTreeReaderStream.cpp b/dbms/src/Storages/MergeTree/MergeTreeReaderStream.cpp
index 9bf1ac7a36c..839be3104e0 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeReaderStream.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeReaderStream.cpp
@@ -112,13 +112,9 @@ void MergeTreeReaderStream::initMarksLoader()
 
     auto load = [this](const String & mrk_path) -> MarkCache::MappedPtr
     {
-        std::cerr << "reading marks from path: " << mrk_path << "\n";
-        std::cerr << "marks: " << marks_count << "\n";
         /// Memory for marks must not be accounted as memory usage for query, because they are stored in shared cache.
         auto temporarily_disable_memory_tracker = getCurrentMemoryTrackerActionLock();
 
-        std::cerr << "data_file_extension: " << data_file_extension << '\n';
-
         size_t file_size = Poco::File(mrk_path).getSize();
         size_t mark_size = mode == ReadingMode::INDEX
             ? index_granularity_info->skip_index_mark_size_in_bytes
diff --git a/dbms/src/Storages/MergeTree/MergeTreeReaderWide.cpp b/dbms/src/Storages/MergeTree/MergeTreeReaderWide.cpp
index 567d9442743..6b9e15fe443 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeReaderWide.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeReaderWide.cpp
@@ -146,8 +146,6 @@ size_t MergeTreeReaderWide::readRows(size_t from_mark, bool continue_reading, si
         throw;
     }
 
-    // std::cerr << "(MergeTreeReaderWide::readRows) read_rows: " << read_rows << "\n";
-
     return read_rows;
 }
 
@@ -169,9 +167,6 @@ void MergeTreeReaderWide::addStreams(const String & name, const IDataType & type
         if (!data_file_exists)
             return;
 
-        std::cerr << "(addStreams) part: " << path << '\n';
-        std::cerr << "(addStreams) marks count: " << data_part->getMarksCount() << "\n";
-
         streams.emplace(stream_name, std::make_unique<MergeTreeReaderStream>(
             path + stream_name, DATA_FILE_EXTENSION, data_part->getMarksCount(),
             all_mark_ranges, settings, mark_cache,
@@ -191,8 +186,6 @@ void MergeTreeReaderWide::readData(
     size_t from_mark, bool continue_reading, size_t max_rows_to_read,
     bool with_offsets)
 {
-    std::cerr << "(MergeTreeReaderWide::readData) name: " << name << "\n";
-    std::cerr << "(MergeTreeReaderWide::readData) max_rows_to_read: " << max_rows_to_read << "\n";
     auto get_stream_getter = [&](bool stream_for_prefix) -> IDataType::InputStreamGetter
     {
         return [&, stream_for_prefix](const IDataType::SubstreamPath & substream_path) -> ReadBuffer *
diff --git a/dbms/src/Storages/MergeTree/MergeTreeSequentialBlockInputStream.cpp b/dbms/src/Storages/MergeTree/MergeTreeSequentialBlockInputStream.cpp
index c1a8d72bbaa..9caf605262a 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeSequentialBlockInputStream.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeSequentialBlockInputStream.cpp
@@ -51,10 +51,6 @@ MergeTreeSequentialBlockInputStream::MergeTreeSequentialBlockInputStream(
         columns_for_reader = data_part->columns.addTypes(columns_to_read);
     }
 
-    std::cerr << "(MergeTreeSequentialBlockInputStream) table: " << storage.getTableName() << "\n";
-    std::cerr << "(MergeTreeSequentialBlockInputStream) part: " << data_part_->getFullPath() << "\n";
-    std::cerr << "(MergeTreeSequentialBlockInputStream) columns_for_reader: " << columns_for_reader.toString() << "\n";
-
     MergeTreeReaderSettings reader_settings =
     {
         /// This is hack
@@ -136,8 +132,6 @@ try
         finish();
     }
 
-    std::cerr << "(MergeTreeSequentialBlockInputStream::readImpl) block: " << res.dumpStructure() << "\n";
-
     return res;
 }
 catch (...)
diff --git a/dbms/src/Storages/MergeTree/MergeTreeThreadSelectBlockInputProcessor.cpp b/dbms/src/Storages/MergeTree/MergeTreeThreadSelectBlockInputProcessor.cpp
index 27b13d5a934..537ccaba2c1 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeThreadSelectBlockInputProcessor.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeThreadSelectBlockInputProcessor.cpp
@@ -70,10 +70,6 @@ bool MergeTreeThreadSelectBlockInputProcessor::getNewTask()
             owned_uncompressed_cache = storage.global_context.getUncompressedCache();
         owned_mark_cache = storage.global_context.getMarkCache();
 
-        std::cerr << "In Part: " << task->data_part->getFullPath() << "\n";
-        std::cerr << "task->columns: " << task->columns.toString() << "\n";
-        std::cerr << "part->columns: " << task->data_part->columns.toString() << "\n";
-
         reader = task->data_part->getReader(task->columns, rest_mark_ranges,
             owned_uncompressed_cache.get(), owned_mark_cache.get(), reader_settings,
             IMergeTreeReader::ValueSizeMap{}, profile_callback);
diff --git a/dbms/src/Storages/MergeTree/MergedColumnOnlyOutputStream.cpp b/dbms/src/Storages/MergeTree/MergedColumnOnlyOutputStream.cpp
index 518321dca9c..5b3da800d99 100644
--- a/dbms/src/Storages/MergeTree/MergedColumnOnlyOutputStream.cpp
+++ b/dbms/src/Storages/MergeTree/MergedColumnOnlyOutputStream.cpp
@@ -14,26 +14,21 @@ MergedColumnOnlyOutputStream::MergedColumnOnlyOutputStream(
     : IMergedBlockOutputStream(data_part),
     header(header_), sync(sync_)
 {
-    // std::cerr << "(MergedColumnOnlyOutputStream) storage: " << storage.getTableName() << "\n";
-    // std::cerr << "(MergedColumnOnlyOutputStream) can_use_adaptive_granularity: " << can_use_adaptive_granularity << "\n";
-    // std::cerr << "(MergedColumnOnlyOutputStream) index_granularity_info: " << !!index_granularity_info_ << "\n";
-    // if (index_granularity_info_)
-    //     std::cerr << "(MergedColumnOnlyOutputStream) index_granularity_info->isAdaptive(): " << index_granularity_info_->is_adaptive << "\n";
-
     MergeTreeWriterSettings writer_settings(
         data_part->storage.global_context.getSettings(),
         index_granularity_info ? index_granularity_info->is_adaptive : data_part->storage.canUseAdaptiveGranularity());
     writer_settings.filename_suffix = filename_suffix;
+    writer_settings.skip_offsets = skip_offsets_;
 
     writer = data_part->getWriter(header.getNamesAndTypesList(), indices_to_recalc, default_codec, writer_settings, index_granularity);
-    writer->setOffsetColumns(offset_columns_, skip_offsets_);
+    writer->setWrittenOffsetColumns(offset_columns_);
     writer->initSkipIndices();
 }
 
 void MergedColumnOnlyOutputStream::write(const Block & block)
 {
     std::set<String> skip_indexes_column_names_set;
-    for (const auto & index : storage.skip_indices) /// FIXME save local indices
+    for (const auto & index : writer->getSkipIndices())
         std::copy(index->columns.cbegin(), index->columns.cend(),
                   std::inserter(skip_indexes_column_names_set, skip_indexes_column_names_set.end()));
     Names skip_indexes_column_names(skip_indexes_column_names_set.begin(), skip_indexes_column_names_set.end());
@@ -44,8 +39,6 @@ void MergedColumnOnlyOutputStream::write(const Block & block)
     if (!rows)
         return;
 
-    std::cerr << "(MergedColumnOnlyOutputStream::write) writing rows: " << rows << "\n";
-
     writer->write(block);
     writer->calculateAndSerializeSkipIndices(skip_indexes_block, rows);
     writer->next();
diff --git a/dbms/src/Storages/tests/gtest_aux_funcs_for_adaptive_granularity.cpp b/dbms/src/Storages/tests/gtest_aux_funcs_for_adaptive_granularity.cpp
index 42544c192ae..0579fd05f5d 100644
--- a/dbms/src/Storages/tests/gtest_aux_funcs_for_adaptive_granularity.cpp
+++ b/dbms/src/Storages/tests/gtest_aux_funcs_for_adaptive_granularity.cpp
@@ -3,7 +3,7 @@
 #include <Columns/ColumnVector.h>
 
 // I know that inclusion of .cpp is not good at all
-#include <Storages/MergeTree/IMergedBlockOutputStream.cpp>
+#include <Storages/MergeTree/IMergeTreeDataPartWriter.cpp>
 
 using namespace DB;
 static Block getBlockWithSize(size_t required_size_in_bytes, size_t size_of_row_in_bytes)
diff --git a/utils/convert-month-partitioned-parts/main.cpp b/utils/convert-month-partitioned-parts/main.cpp
index d0b4d7571fa..c1b89f2251e 100644
--- a/utils/convert-month-partitioned-parts/main.cpp
+++ b/utils/convert-month-partitioned-parts/main.cpp
@@ -1,5 +1,5 @@
 #include <Storages/MergeTree/MergeTreePartInfo.h>
-#include <Storages/MergeTree/MergeTreeDataPart.h>
+#include <Storages/MergeTree/IMergeTreeDataPart.h>
 #include <DataTypes/DataTypeDate.h>
 #include <IO/ReadBufferFromFile.h>
 #include <IO/WriteBufferFromFile.h>
@@ -80,7 +80,7 @@ void run(String part_path, String date_column, String dest_path)
     checksums.files["count.txt"].file_size = count_out_hashing.count();
     checksums.files["count.txt"].file_hash = count_out_hashing.getHash();
 
-    MergeTreeDataPart::MinMaxIndex minmax_idx(min_date, max_date);
+    IMergeTreeDataPart::MinMaxIndex minmax_idx(min_date, max_date);
     Names minmax_idx_columns = {date_column};
     DataTypes minmax_idx_column_types = {std::make_shared<DataTypeDate>()};
     minmax_idx.store(minmax_idx_columns, minmax_idx_column_types, new_tmp_part_path_str, checksums);