ClickHouse/src/Processors/QueryPlan/ReadFromMergeTree.cpp

#include <algorithm>
#include <functional>
#include <memory>
#include <numeric>
#include <queue>
#include <stdexcept>
#include <IO/Operators.h>
#include <Interpreters/ExpressionAnalyzer.h>
#include <Interpreters/TreeRewriter.h>
#include <Interpreters/Context.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTSelectQuery.h>
#include <Processors/ConcatProcessor.h>
#include <Processors/Merges/AggregatingSortedTransform.h>
#include <Processors/Merges/CollapsingSortedTransform.h>
#include <Processors/Merges/GraphiteRollupSortedTransform.h>
#include <Processors/Merges/MergingSortedTransform.h>
#include <Processors/Merges/ReplacingSortedTransform.h>
#include <Processors/Merges/SummingSortedTransform.h>
#include <Processors/Merges/VersionedCollapsingTransform.h>
#include <Processors/QueryPlan/PartsSplitter.h>
#include <Processors/QueryPlan/ReadFromMergeTree.h>
#include <Processors/Sources/NullSource.h>
#include <Processors/Transforms/ExpressionTransform.h>
#include <Processors/Transforms/FilterTransform.h>
#include <Processors/Transforms/ReverseTransform.h>
#include <QueryPipeline/QueryPipelineBuilder.h>
#include <Storages/MergeTree/MergeTreeDataSelectExecutor.h>
#include <Storages/MergeTree/MergeTreeInOrderSelectProcessor.h>
#include <Storages/MergeTree/MergeTreeReadPool.h>
#include <Storages/MergeTree/MergeTreeReverseSelectProcessor.h>
#include <Storages/MergeTree/MergeTreeThreadSelectProcessor.h>
#include <Storages/VirtualColumnUtils.h>
#include <Common/logger_useful.h>
#include <base/sort.h>
#include <Poco/Logger.h>
#include <Common/JSONBuilder.h>

namespace ProfileEvents
{
    extern const Event SelectedParts;
    extern const Event SelectedRanges;
    extern const Event SelectedMarks;
}

namespace DB
{

namespace ErrorCodes
{
    extern const int INDEX_NOT_USED;
    extern const int LOGICAL_ERROR;
}

static MergeTreeReaderSettings getMergeTreeReaderSettings(
    const ContextPtr & context, const SelectQueryInfo & query_info)
{
    const auto & settings = context->getSettingsRef();
    return
    {
        .read_settings = context->getReadSettings(),
        .save_marks_in_cache = true,
        .checksum_on_read = settings.checksum_on_read,
        .read_in_order = query_info.input_order_info != nullptr,
        .apply_deleted_mask = context->applyDeletedMask(),
    };
}

static const PrewhereInfoPtr & getPrewhereInfo(const SelectQueryInfo & query_info)
{
    return query_info.projection ? query_info.projection->prewhere_info
                                 : query_info.prewhere_info;
}

ReadFromMergeTree::ReadFromMergeTree(
    MergeTreeData::DataPartsVector parts_,
    Names real_column_names_,
    Names virt_column_names_,
    const MergeTreeData & data_,
    const SelectQueryInfo & query_info_,
    StorageSnapshotPtr storage_snapshot_,
    ContextPtr context_,
    size_t max_block_size_,
    size_t num_streams_,
    bool sample_factor_column_queried_,
    std::shared_ptr<PartitionIdToMaxBlock> max_block_numbers_to_read_,
    Poco::Logger * log_,
    MergeTreeDataSelectAnalysisResultPtr analyzed_result_ptr_,
    bool enable_parallel_reading)
    : ISourceStep(DataStream{.header = MergeTreeBaseSelectProcessor::transformHeader(
        storage_snapshot_->getSampleBlockForColumns(real_column_names_),
        getPrewhereInfo(query_info_),
        data_.getPartitionValueType(),
        virt_column_names_)})
    , reader_settings(getMergeTreeReaderSettings(context_, query_info_))
    , prepared_parts(std::move(parts_))
    , real_column_names(std::move(real_column_names_))
    , virt_column_names(std::move(virt_column_names_))
    , data(data_)
    , query_info(query_info_)
    , prewhere_info(getPrewhereInfo(query_info))
    , actions_settings(ExpressionActionsSettings::fromContext(context_))
    , storage_snapshot(std::move(storage_snapshot_))
    , metadata_for_reading(storage_snapshot->getMetadataForQuery())
    , context(std::move(context_))
    , max_block_size(max_block_size_)
    , requested_num_streams(num_streams_)
    , preferred_block_size_bytes(context->getSettingsRef().preferred_block_size_bytes)
    , preferred_max_column_in_block_size_bytes(context->getSettingsRef().preferred_max_column_in_block_size_bytes)
    , sample_factor_column_queried(sample_factor_column_queried_)
    , max_block_numbers_to_read(std::move(max_block_numbers_to_read_))
    , log(log_)
    , analyzed_result_ptr(analyzed_result_ptr_)
{
    if (sample_factor_column_queried)
    {
        /// Only _sample_factor virtual column is added by ReadFromMergeTree
        /// Other virtual columns are added by MergeTreeBaseSelectProcessor.
        auto type = std::make_shared<DataTypeFloat64>();
        output_stream->header.insert({type->createColumn(), type, "_sample_factor"});
    }

    if (enable_parallel_reading)
        read_task_callback = context->getMergeTreeReadTaskCallback();

    /// Add explicit description.
    setStepDescription(data.getStorageID().getFullNameNotQuoted());

    { /// build sort description for output stream
        SortDescription sort_description;
        const Names & sorting_key_columns = storage_snapshot->getMetadataForQuery()->getSortingKeyColumns();
        const Block & header = output_stream->header;
        const int sort_direction = getSortDirection();
        for (const auto & column_name : sorting_key_columns)
        {
            if (std::find_if(header.begin(), header.end(), [&](ColumnWithTypeAndName const & col) { return col.name == column_name; })
                == header.end())
                break;
            sort_description.emplace_back(column_name, sort_direction);
        }
        if (!sort_description.empty())
        {
            auto const & settings = context->getSettingsRef();
            if ((settings.optimize_read_in_order || settings.optimize_aggregation_in_order) && query_info.getInputOrderInfo())
                output_stream->sort_mode = DataStream::SortMode::Port;
            else
                output_stream->sort_mode = DataStream::SortMode::Chunk;
        }

        output_stream->sort_description = std::move(sort_description);

    }
}

Pipe ReadFromMergeTree::readFromPool(
    RangesInDataParts parts_with_range,
    Names required_columns,
    size_t max_streams,
    size_t min_marks_for_concurrent_read,
    bool use_uncompressed_cache)
{
    Pipes pipes;
    size_t sum_marks = 0;
    size_t total_rows = 0;

    for (const auto & part : parts_with_range)
    {
        sum_marks += part.getMarksCount();
        total_rows += part.getRowsCount();
    }

    const auto & settings = context->getSettingsRef();
    const auto & client_info = context->getClientInfo();
    MergeTreeReadPool::BackoffSettings backoff_settings(settings);

    auto pool = std::make_shared<MergeTreeReadPool>(
        max_streams,
        sum_marks,
        min_marks_for_concurrent_read,
        std::move(parts_with_range),
        data,
        storage_snapshot,
        prewhere_info,
        required_columns,
        virt_column_names,
        backoff_settings,
        settings.preferred_block_size_bytes,
        false);

    auto * logger = &Poco::Logger::get(data.getLogName() + " (SelectExecutor)");
    LOG_DEBUG(logger, "Reading approx. {} rows with {} streams", total_rows, max_streams);

    for (size_t i = 0; i < max_streams; ++i)
    {
        std::optional<ParallelReadingExtension> extension;
        if (read_task_callback)
        {
            extension = ParallelReadingExtension
            {
                .callback = read_task_callback.value(),
                .count_participating_replicas = client_info.count_participating_replicas,
                .number_of_current_replica = client_info.number_of_current_replica,
                .colums_to_read = required_columns
            };
        }

        auto source = std::make_shared<MergeTreeThreadSelectProcessor>(
            i, pool, min_marks_for_concurrent_read, max_block_size,
            settings.preferred_block_size_bytes, settings.preferred_max_column_in_block_size_bytes,
            data, storage_snapshot, use_uncompressed_cache,
            prewhere_info, actions_settings, reader_settings, virt_column_names, std::move(extension));

        /// Set the approximate number of rows for the first source only
        /// In case of parallel processing on replicas do not set approximate rows at all.
        /// Because the value will be identical on every replicas and will be accounted
        /// multiple times (settings.max_parallel_replicas times more)
        if (i == 0 && !client_info.collaborate_with_initiator)
            source->addTotalRowsApprox(total_rows);

        pipes.emplace_back(std::move(source));
    }

    return Pipe::unitePipes(std::move(pipes));
}

template<typename TSource>
ProcessorPtr ReadFromMergeTree::createSource(
    const RangesInDataPart & part,
    const Names & required_columns,
    bool use_uncompressed_cache,
    bool has_limit_below_one_block)
{
    const auto & client_info = context->getClientInfo();
    std::optional<ParallelReadingExtension> extension;
    if (read_task_callback)
    {
        extension = ParallelReadingExtension
        {
            .callback = read_task_callback.value(),
            .count_participating_replicas = client_info.count_participating_replicas,
            .number_of_current_replica = client_info.number_of_current_replica,
            .colums_to_read = required_columns
        };
    }

    return std::make_shared<TSource>(
            data, storage_snapshot, part.data_part, max_block_size, preferred_block_size_bytes,
            preferred_max_column_in_block_size_bytes, required_columns, part.ranges, use_uncompressed_cache, prewhere_info,
            actions_settings, reader_settings, virt_column_names, part.part_index_in_query, has_limit_below_one_block, std::move(extension));
}

Pipe ReadFromMergeTree::readInOrder(
    RangesInDataParts parts_with_range,
    Names required_columns,
    ReadType read_type,
    bool use_uncompressed_cache,
    UInt64 limit)
{
    Pipes pipes;
    /// For reading in order it makes sense to read only
    /// one range per task to reduce number of read rows.
    bool has_limit_below_one_block = read_type != ReadType::Default && limit && limit < max_block_size;

    for (const auto & part : parts_with_range)
    {
        auto source = read_type == ReadType::InReverseOrder
                    ? createSource<MergeTreeReverseSelectProcessor>(part, required_columns, use_uncompressed_cache, has_limit_below_one_block)
                    : createSource<MergeTreeInOrderSelectProcessor>(part, required_columns, use_uncompressed_cache, has_limit_below_one_block);

        pipes.emplace_back(std::move(source));
    }

    auto pipe = Pipe::unitePipes(std::move(pipes));

    if (read_type == ReadType::InReverseOrder)
    {
        pipe.addSimpleTransform([&](const Block & header)
        {
            return std::make_shared<ReverseTransform>(header);
        });
    }

    return pipe;
}

Pipe ReadFromMergeTree::read(
    RangesInDataParts parts_with_range, Names required_columns, ReadType read_type,
    size_t max_streams, size_t min_marks_for_concurrent_read, bool use_uncompressed_cache)
{
    if (read_type == ReadType::Default && max_streams > 1)
        return readFromPool(parts_with_range, required_columns, max_streams,
                            min_marks_for_concurrent_read, use_uncompressed_cache);

    auto pipe = readInOrder(parts_with_range, required_columns, read_type, use_uncompressed_cache, 0);

    /// Use ConcatProcessor to concat sources together.
    /// It is needed to read in parts order (and so in PK order) if single thread is used.
    if (read_type == ReadType::Default && pipe.numOutputPorts() > 1)
        pipe.addTransform(std::make_shared<ConcatProcessor>(pipe.getHeader(), pipe.numOutputPorts()));

    return pipe;
}

namespace
{

struct PartRangesReadInfo
{
    std::vector<size_t> sum_marks_in_parts;

    size_t sum_marks = 0;
    size_t total_rows = 0;
    size_t adaptive_parts = 0;
    size_t index_granularity_bytes = 0;
    size_t max_marks_to_use_cache = 0;
    size_t min_marks_for_concurrent_read = 0;

    bool use_uncompressed_cache = false;

    static bool checkAllPartsOnRemoteFS(const RangesInDataParts & parts)
    {
        for (const auto & part : parts)
        {
            if (!part.data_part->isStoredOnRemoteDisk())
                return false;
        }
        return true;
    }

    PartRangesReadInfo(
        const RangesInDataParts & parts,
        const Settings & settings,
        const MergeTreeSettings & data_settings)
    {
        /// Count marks for each part.
        sum_marks_in_parts.resize(parts.size());
        for (size_t i = 0; i < parts.size(); ++i)
        {
            total_rows += parts[i].getRowsCount();
            sum_marks_in_parts[i] = parts[i].getMarksCount();
            sum_marks += sum_marks_in_parts[i];

            if (parts[i].data_part->index_granularity_info.is_adaptive)
                ++adaptive_parts;
        }

        if (adaptive_parts > parts.size() / 2)
            index_granularity_bytes = data_settings.index_granularity_bytes;

        max_marks_to_use_cache = MergeTreeDataSelectExecutor::roundRowsOrBytesToMarks(
            settings.merge_tree_max_rows_to_use_cache,
            settings.merge_tree_max_bytes_to_use_cache,
            data_settings.index_granularity,
            index_granularity_bytes);

        auto all_parts_on_remote_disk = checkAllPartsOnRemoteFS(parts);
        min_marks_for_concurrent_read = MergeTreeDataSelectExecutor::minMarksForConcurrentRead(
            all_parts_on_remote_disk ? settings.merge_tree_min_rows_for_concurrent_read_for_remote_filesystem
                                     : settings.merge_tree_min_rows_for_concurrent_read,
            all_parts_on_remote_disk ? settings.merge_tree_min_bytes_for_concurrent_read_for_remote_filesystem
                                     : settings.merge_tree_min_bytes_for_concurrent_read,
            data_settings.index_granularity,
            index_granularity_bytes,
            sum_marks);

        use_uncompressed_cache = settings.use_uncompressed_cache;
        if (sum_marks > max_marks_to_use_cache)
            use_uncompressed_cache = false;
    }
};

}

Pipe ReadFromMergeTree::spreadMarkRangesAmongStreams(
    RangesInDataParts && parts_with_ranges,
    const Names & column_names)
{
    const auto & settings = context->getSettingsRef();
    const auto data_settings = data.getSettings();

    PartRangesReadInfo info(parts_with_ranges, settings, *data_settings);

    if (0 == info.sum_marks)
        return {};

    size_t num_streams = requested_num_streams;
    if (num_streams > 1)
    {
        /// Reduce the number of num_streams if the data is small.
        if (info.sum_marks < num_streams * info.min_marks_for_concurrent_read && parts_with_ranges.size() < num_streams)
            num_streams = std::max((info.sum_marks + info.min_marks_for_concurrent_read - 1) / info.min_marks_for_concurrent_read, parts_with_ranges.size());
    }

    return read(std::move(parts_with_ranges), column_names, ReadType::Default,
                num_streams, info.min_marks_for_concurrent_read, info.use_uncompressed_cache);
}

static ActionsDAGPtr createProjection(const Block & header)
{
    auto projection = std::make_shared<ActionsDAG>(header.getNamesAndTypesList());
    projection->removeUnusedActions(header.getNames());
    projection->projectInput();
    return projection;
}

Pipe ReadFromMergeTree::spreadMarkRangesAmongStreamsWithOrder(
    RangesInDataParts && parts_with_ranges,
    const Names & column_names,
    ActionsDAGPtr & out_projection,
    const InputOrderInfoPtr & input_order_info)
{
    const auto & settings = context->getSettingsRef();
    const auto data_settings = data.getSettings();

    PartRangesReadInfo info(parts_with_ranges, settings, *data_settings);

    Pipes res;

    if (info.sum_marks == 0)
        return {};

    /// Let's split ranges to avoid reading much data.
    auto split_ranges = [rows_granularity = data_settings->index_granularity, max_block_size = max_block_size]
        (const auto & ranges, int direction)
    {
        MarkRanges new_ranges;
        const size_t max_marks_in_range = (max_block_size + rows_granularity - 1) / rows_granularity;
        size_t marks_in_range = 1;

        if (direction == 1)
        {
            /// Split first few ranges to avoid reading much data.
            bool split = false;
            for (auto range : ranges)
            {
                while (!split && range.begin + marks_in_range < range.end)
                {
                    new_ranges.emplace_back(range.begin, range.begin + marks_in_range);
                    range.begin += marks_in_range;
                    marks_in_range *= 2;

                    if (marks_in_range > max_marks_in_range)
                        split = true;
                }
                new_ranges.emplace_back(range.begin, range.end);
            }
        }
        else
        {
            /// Split all ranges to avoid reading much data, because we have to
            ///  store whole range in memory to reverse it.
            for (auto it = ranges.rbegin(); it != ranges.rend(); ++it)
            {
                auto range = *it;
                while (range.begin + marks_in_range < range.end)
                {
                    new_ranges.emplace_front(range.end - marks_in_range, range.end);
                    range.end -= marks_in_range;
                    marks_in_range = std::min(marks_in_range * 2, max_marks_in_range);
                }
                new_ranges.emplace_front(range.begin, range.end);
            }
        }

        return new_ranges;
    };

    const size_t min_marks_per_stream = (info.sum_marks - 1) / requested_num_streams + 1;
    bool need_preliminary_merge = (parts_with_ranges.size() > settings.read_in_order_two_level_merge_threshold);

    Pipes pipes;

    for (size_t i = 0; i < requested_num_streams && !parts_with_ranges.empty(); ++i)
    {
        size_t need_marks = min_marks_per_stream;
        RangesInDataParts new_parts;

        /// Loop over parts.
        /// We will iteratively take part or some subrange of a part from the back
        ///  and assign a stream to read from it.
        while (need_marks > 0 && !parts_with_ranges.empty())
        {
            RangesInDataPart part = parts_with_ranges.back();
            parts_with_ranges.pop_back();
            size_t & marks_in_part = info.sum_marks_in_parts.back();

            /// We will not take too few rows from a part.
            if (marks_in_part >= info.min_marks_for_concurrent_read &&
                need_marks < info.min_marks_for_concurrent_read)
                need_marks = info.min_marks_for_concurrent_read;

            /// Do not leave too few rows in the part.
            if (marks_in_part > need_marks &&
                marks_in_part - need_marks < info.min_marks_for_concurrent_read)
                need_marks = marks_in_part;

            MarkRanges ranges_to_get_from_part;

            /// We take full part if it contains enough marks or
            /// if we know limit and part contains less than 'limit' rows.
            bool take_full_part = marks_in_part <= need_marks
                || (input_order_info->limit && input_order_info->limit < part.getRowsCount());

            /// We take the whole part if it is small enough.
            if (take_full_part)
            {
                ranges_to_get_from_part = part.ranges;

                need_marks -= marks_in_part;
                info.sum_marks_in_parts.pop_back();
            }
            else
            {
                /// Loop through ranges in part. Take enough ranges to cover "need_marks".
                while (need_marks > 0)
                {
                    if (part.ranges.empty())
                        throw Exception("Unexpected end of ranges while spreading marks among streams",
                                        ErrorCodes::LOGICAL_ERROR);

                    MarkRange & range = part.ranges.front();

                    const size_t marks_in_range = range.end - range.begin;
                    const size_t marks_to_get_from_range = std::min(marks_in_range, need_marks);

                    ranges_to_get_from_part.emplace_back(range.begin, range.begin + marks_to_get_from_range);
                    range.begin += marks_to_get_from_range;
                    marks_in_part -= marks_to_get_from_range;
                    need_marks -= marks_to_get_from_range;
                    if (range.begin == range.end)
                        part.ranges.pop_front();
                }
                parts_with_ranges.emplace_back(part);
            }

            ranges_to_get_from_part = split_ranges(ranges_to_get_from_part, input_order_info->direction);
            new_parts.emplace_back(part.data_part, part.part_index_in_query, std::move(ranges_to_get_from_part));
        }

        auto read_type = input_order_info->direction == 1
                       ? ReadFromMergeTree::ReadType::InOrder
                       : ReadFromMergeTree::ReadType::InReverseOrder;

        pipes.emplace_back(readInOrder(std::move(new_parts), column_names, read_type,
                                        info.use_uncompressed_cache, input_order_info->limit));
    }

    if (need_preliminary_merge)
    {
        size_t prefix_size = input_order_info->used_prefix_of_sorting_key_size;
        auto order_key_prefix_ast = metadata_for_reading->getSortingKey().expression_list_ast->clone();
        order_key_prefix_ast->children.resize(prefix_size);

        auto syntax_result = TreeRewriter(context).analyze(order_key_prefix_ast, metadata_for_reading->getColumns().getAllPhysical());
        auto sorting_key_prefix_expr = ExpressionAnalyzer(order_key_prefix_ast, syntax_result, context).getActionsDAG(false);
        const auto & sorting_columns = metadata_for_reading->getSortingKey().column_names;

        SortDescription sort_description;
        sort_description.compile_sort_description = settings.compile_sort_description;
        sort_description.min_count_to_compile_sort_description = settings.min_count_to_compile_sort_description;

        for (size_t j = 0; j < prefix_size; ++j)
            sort_description.emplace_back(sorting_columns[j], input_order_info->direction);

        auto sorting_key_expr = std::make_shared<ExpressionActions>(sorting_key_prefix_expr);

        for (auto & pipe : pipes)
        {
            /// Drop temporary columns, added by 'sorting_key_prefix_expr'
            out_projection = createProjection(pipe.getHeader());

            pipe.addSimpleTransform([sorting_key_expr](const Block & header)
            {
                return std::make_shared<ExpressionTransform>(header, sorting_key_expr);
            });

            if (pipe.numOutputPorts() > 1)
            {
                auto transform = std::make_shared<MergingSortedTransform>(
                        pipe.getHeader(),
                        pipe.numOutputPorts(),
                        sort_description,
                        max_block_size,
                        SortingQueueStrategy::Batch);

                pipe.addTransform(std::move(transform));
            }
        }
    }

    return Pipe::unitePipes(std::move(pipes));
}

static void addMergingFinal(
    Pipe & pipe,
    const SortDescription & sort_description,
    MergeTreeData::MergingParams merging_params,
    Names partition_key_columns,
    size_t max_block_size)
{
    const auto & header = pipe.getHeader();
    size_t num_outputs = pipe.numOutputPorts();

    auto now = time(nullptr);

    auto get_merging_processor = [&]() -> MergingTransformPtr
    {
        switch (merging_params.mode)
        {
            case MergeTreeData::MergingParams::Ordinary:
                return std::make_shared<MergingSortedTransform>(header, num_outputs,
                            sort_description, max_block_size, SortingQueueStrategy::Batch);

            case MergeTreeData::MergingParams::Collapsing:
                return std::make_shared<CollapsingSortedTransform>(header, num_outputs,
                            sort_description, merging_params.sign_column, true, max_block_size);

            case MergeTreeData::MergingParams::Summing:
                return std::make_shared<SummingSortedTransform>(header, num_outputs,
                            sort_description, merging_params.columns_to_sum, partition_key_columns, max_block_size);

            case MergeTreeData::MergingParams::Aggregating:
                return std::make_shared<AggregatingSortedTransform>(header, num_outputs,
                            sort_description, max_block_size);

            case MergeTreeData::MergingParams::Replacing:
                return std::make_shared<ReplacingSortedTransform>(header, num_outputs,
                            sort_description, merging_params.version_column, max_block_size);

            case MergeTreeData::MergingParams::VersionedCollapsing:
                return std::make_shared<VersionedCollapsingTransform>(header, num_outputs,
                            sort_description, merging_params.sign_column, max_block_size);

            case MergeTreeData::MergingParams::Graphite:
                return std::make_shared<GraphiteRollupSortedTransform>(header, num_outputs,
                            sort_description, max_block_size, merging_params.graphite_params, now);
        }

        __builtin_unreachable();
    };

    pipe.addTransform(get_merging_processor());
}


Pipe ReadFromMergeTree::spreadMarkRangesAmongStreamsFinal(
    RangesInDataParts && parts_with_ranges,
    const Names & column_names,
    ActionsDAGPtr & out_projection)
{
    const auto & settings = context->getSettingsRef();
    const auto data_settings = data.getSettings();

    PartRangesReadInfo info(parts_with_ranges, settings, *data_settings);

    size_t num_streams = requested_num_streams;
    if (num_streams > settings.max_final_threads)
        num_streams = settings.max_final_threads;

    /// If setting do_not_merge_across_partitions_select_final is true than we won't merge parts from different partitions.
    /// We have all parts in parts vector, where parts with same partition are nearby.
    /// So we will store iterators pointed to the beginning of each partition range (and parts.end()),
    /// then we will create a pipe for each partition that will run selecting processor and merging processor
    /// for the parts with this partition. In the end we will unite all the pipes.
    std::vector<RangesInDataParts::iterator> parts_to_merge_ranges;
    auto it = parts_with_ranges.begin();
    parts_to_merge_ranges.push_back(it);

    if (settings.do_not_merge_across_partitions_select_final)
    {
        while (it != parts_with_ranges.end())
        {
            it = std::find_if(
                it, parts_with_ranges.end(), [&it](auto & part) { return it->data_part->info.partition_id != part.data_part->info.partition_id; });
            parts_to_merge_ranges.push_back(it);
        }
        /// We divide threads for each partition equally. But we will create at least the number of partitions threads.
        /// (So, the total number of threads could be more than initial num_streams.
        num_streams /= (parts_to_merge_ranges.size() - 1);
    }
    else
    {
        /// If do_not_merge_across_partitions_select_final is false we just merge all the parts.
        parts_to_merge_ranges.push_back(parts_with_ranges.end());
    }

    Pipes partition_pipes;

    /// If do_not_merge_across_partitions_select_final is true and num_streams > 1
    /// we will store lonely parts with level > 0 to use parallel select on them.
    std::vector<RangesInDataPart> lonely_parts;
    size_t sum_marks_in_lonely_parts = 0;

    for (size_t range_index = 0; range_index < parts_to_merge_ranges.size() - 1; ++range_index)
    {
        Pipes pipes;
        {
            RangesInDataParts new_parts;

            /// If do_not_merge_across_partitions_select_final is true and there is only one part in partition
            /// with level > 0 then we won't postprocess this part and if num_streams > 1 we
            /// can use parallel select on such parts. We save such parts in one vector and then use
            /// MergeTreeReadPool and MergeTreeThreadSelectProcessor for parallel select.
            if (num_streams > 1 && settings.do_not_merge_across_partitions_select_final &&
                std::distance(parts_to_merge_ranges[range_index], parts_to_merge_ranges[range_index + 1]) == 1 &&
                parts_to_merge_ranges[range_index]->data_part->info.level > 0)
            {
                sum_marks_in_lonely_parts += parts_to_merge_ranges[range_index]->getMarksCount();
                lonely_parts.push_back(std::move(*parts_to_merge_ranges[range_index]));
                continue;
            }
            else
            {
                for (auto part_it = parts_to_merge_ranges[range_index]; part_it != parts_to_merge_ranges[range_index + 1]; ++part_it)
                {
                    new_parts.emplace_back(part_it->data_part, part_it->part_index_in_query, part_it->ranges);
                }
            }

            if (new_parts.empty())
                continue;

            if (num_streams > 1 && metadata_for_reading->hasPrimaryKey())
            {
                // Let's split parts into layers to ensure data parallelism of FINAL.
                auto reading_step_getter = [this, &column_names, &info](auto parts)
                {
                    return this->read(
                        std::move(parts),
                        column_names,
                        ReadFromMergeTree::ReadType::InOrder,
                        1 /* num_streams */,
                        0 /* min_marks_for_concurrent_read */,
                        info.use_uncompressed_cache);
                };
                pipes = buildPipesForReadingByPKRanges(
                    metadata_for_reading->getPrimaryKey(), std::move(new_parts), num_streams, context, std::move(reading_step_getter));
            }
            else
            {
                pipes.emplace_back(read(
                    std::move(new_parts), column_names, ReadFromMergeTree::ReadType::InOrder, num_streams, 0, info.use_uncompressed_cache));
            }

            /// Drop temporary columns, added by 'sorting_key_expr'
            if (!out_projection)
                out_projection = createProjection(pipes.front().getHeader());
        }

        auto sorting_expr = std::make_shared<ExpressionActions>(
            metadata_for_reading->getSortingKey().expression->getActionsDAG().clone());

        for (auto & pipe : pipes)
            pipe.addSimpleTransform([sorting_expr](const Block & header)
                                    { return std::make_shared<ExpressionTransform>(header, sorting_expr); });

        /// If do_not_merge_across_partitions_select_final is true and there is only one part in partition
        /// with level > 0 then we won't postprocess this part
        if (settings.do_not_merge_across_partitions_select_final &&
            std::distance(parts_to_merge_ranges[range_index], parts_to_merge_ranges[range_index + 1]) == 1 &&
            parts_to_merge_ranges[range_index]->data_part->info.level > 0)
        {
            partition_pipes.emplace_back(Pipe::unitePipes(std::move(pipes)));
            continue;
        }

        Names sort_columns = metadata_for_reading->getSortingKeyColumns();
        SortDescription sort_description;
        sort_description.compile_sort_description = settings.compile_sort_description;
        sort_description.min_count_to_compile_sort_description = settings.min_count_to_compile_sort_description;

        size_t sort_columns_size = sort_columns.size();
        sort_description.reserve(sort_columns_size);

        Names partition_key_columns = metadata_for_reading->getPartitionKey().column_names;

        for (size_t i = 0; i < sort_columns_size; ++i)
            sort_description.emplace_back(sort_columns[i], 1, 1);

        for (auto & pipe : pipes)
            addMergingFinal(
                pipe,
                sort_description,
                data.merging_params,
                partition_key_columns,
                max_block_size);

        partition_pipes.emplace_back(Pipe::unitePipes(std::move(pipes)));
    }

    if (!lonely_parts.empty())
    {
        size_t num_streams_for_lonely_parts = num_streams * lonely_parts.size();

        const size_t min_marks_for_concurrent_read = MergeTreeDataSelectExecutor::minMarksForConcurrentRead(
            settings.merge_tree_min_rows_for_concurrent_read,
            settings.merge_tree_min_bytes_for_concurrent_read,
            data_settings->index_granularity,
            info.index_granularity_bytes,
            sum_marks_in_lonely_parts);

        /// Reduce the number of num_streams_for_lonely_parts if the data is small.
        if (sum_marks_in_lonely_parts < num_streams_for_lonely_parts * min_marks_for_concurrent_read && lonely_parts.size() < num_streams_for_lonely_parts)
            num_streams_for_lonely_parts = std::max((sum_marks_in_lonely_parts + min_marks_for_concurrent_read - 1) / min_marks_for_concurrent_read, lonely_parts.size());

        auto pipe = read(std::move(lonely_parts), column_names, ReadFromMergeTree::ReadType::Default,
                num_streams_for_lonely_parts, min_marks_for_concurrent_read, info.use_uncompressed_cache);

        /// Drop temporary columns, added by 'sorting_key_expr'
        if (!out_projection)
            out_projection = createProjection(pipe.getHeader());

        auto sorting_expr = std::make_shared<ExpressionActions>(
            metadata_for_reading->getSortingKey().expression->getActionsDAG().clone());

        pipe.addSimpleTransform([sorting_expr](const Block & header)
        {
            return std::make_shared<ExpressionTransform>(header, sorting_expr);
        });

        partition_pipes.emplace_back(std::move(pipe));
    }

    return Pipe::unitePipes(std::move(partition_pipes));
}

MergeTreeDataSelectAnalysisResultPtr ReadFromMergeTree::selectRangesToRead(MergeTreeData::DataPartsVector parts) const
{
    return selectRangesToRead(
        std::move(parts),
        prewhere_info,
        added_filter_nodes,
        storage_snapshot->metadata,
        storage_snapshot->getMetadataForQuery(),
        query_info,
        context,
        requested_num_streams,
        max_block_numbers_to_read,
        data,
        real_column_names,
        sample_factor_column_queried,
        log);
}

MergeTreeDataSelectAnalysisResultPtr ReadFromMergeTree::selectRangesToRead(
    MergeTreeData::DataPartsVector parts,
    const PrewhereInfoPtr & prewhere_info,
    const ActionDAGNodes & added_filter_nodes,
    const StorageMetadataPtr & metadata_snapshot_base,
    const StorageMetadataPtr & metadata_snapshot,
    const SelectQueryInfo & query_info,
    ContextPtr context,
    unsigned num_streams,
    std::shared_ptr<PartitionIdToMaxBlock> max_block_numbers_to_read,
    const MergeTreeData & data,
    const Names & real_column_names,
    bool sample_factor_column_queried,
    Poco::Logger * log)
{
    AnalysisResult result;
    const auto & settings = context->getSettingsRef();

    size_t total_parts = parts.size();

    /// TODO Support row_policy_filter and additional_filters
    auto part_values = MergeTreeDataSelectExecutor::filterPartsByVirtualColumns(data, parts, query_info.query, context);
    if (part_values && part_values->empty())
        return std::make_shared<MergeTreeDataSelectAnalysisResult>(MergeTreeDataSelectAnalysisResult{.result = std::move(result)});

    result.column_names_to_read = real_column_names;

    /// If there are only virtual columns in the query, you must request at least one non-virtual one.
    if (result.column_names_to_read.empty())
    {
        NamesAndTypesList available_real_columns = metadata_snapshot->getColumns().getAllPhysical();
        result.column_names_to_read.push_back(ExpressionActions::getSmallestColumn(available_real_columns));
    }

    // storage_snapshot->check(result.column_names_to_read);

    // Build and check if primary key is used when necessary
    const auto & primary_key = metadata_snapshot->getPrimaryKey();
    Names primary_key_columns = primary_key.column_names;
    std::optional<KeyCondition> key_condition;

    if (settings.query_plan_optimize_primary_key)
    {
        ActionDAGNodes nodes;
        if (prewhere_info)
        {
            {
                const auto & node = prewhere_info->prewhere_actions->findInOutputs(prewhere_info->prewhere_column_name);
                nodes.nodes.push_back(&node);
            }

            if (prewhere_info->row_level_filter)
            {
                const auto & node = prewhere_info->row_level_filter->findInOutputs(prewhere_info->row_level_column_name);
                nodes.nodes.push_back(&node);
            }
        }

        for (const auto & node : added_filter_nodes.nodes)
            nodes.nodes.push_back(node);

        key_condition.emplace(
            std::move(nodes), query_info.syntax_analyzer_result, query_info.prepared_sets, context, primary_key_columns, primary_key.expression);
    }
    else
    {
        key_condition.emplace(query_info, context, primary_key_columns, primary_key.expression);
    }

    if (settings.force_primary_key && key_condition->alwaysUnknownOrTrue())
    {
        return std::make_shared<MergeTreeDataSelectAnalysisResult>(MergeTreeDataSelectAnalysisResult{
            .result = std::make_exception_ptr(Exception(
                ErrorCodes::INDEX_NOT_USED,
                "Primary key ({}) is not used and setting 'force_primary_key' is set",
                fmt::join(primary_key_columns, ", ")))});
    }
    LOG_DEBUG(log, "Key condition: {}", key_condition->toString());

    if (key_condition->alwaysFalse())
        return std::make_shared<MergeTreeDataSelectAnalysisResult>(MergeTreeDataSelectAnalysisResult{.result = std::move(result)});

    const auto & select = query_info.query->as<ASTSelectQuery &>();

    size_t total_marks_pk = 0;
    size_t parts_before_pk = 0;
    try
    {
        MergeTreeDataSelectExecutor::filterPartsByPartition(
            parts,
            part_values,
            metadata_snapshot_base,
            data,
            query_info,
            context,
            max_block_numbers_to_read.get(),
            log,
            result.index_stats);

        result.sampling = MergeTreeDataSelectExecutor::getSampling(
            select,
            metadata_snapshot->getColumns().getAllPhysical(),
            parts,
            *key_condition,
            data,
            metadata_snapshot,
            context,
            sample_factor_column_queried,
            log);

        if (result.sampling.read_nothing)
            return std::make_shared<MergeTreeDataSelectAnalysisResult>(MergeTreeDataSelectAnalysisResult{.result = std::move(result)});

        for (const auto & part : parts)
            total_marks_pk += part->index_granularity.getMarksCountWithoutFinal();
        parts_before_pk = parts.size();

        auto reader_settings = getMergeTreeReaderSettings(context, query_info);

        bool use_skip_indexes = settings.use_skip_indexes;
        if (select.final() && !settings.use_skip_indexes_if_final)
            use_skip_indexes = false;

        result.parts_with_ranges = MergeTreeDataSelectExecutor::filterPartsByPrimaryKeyAndSkipIndexes(
            std::move(parts),
            metadata_snapshot,
            query_info,
            context,
            *key_condition,
            reader_settings,
            log,
            num_streams,
            result.index_stats,
            use_skip_indexes);
    }
    catch (...)
    {
        return std::make_shared<MergeTreeDataSelectAnalysisResult>(MergeTreeDataSelectAnalysisResult{.result = std::current_exception()});
    }

    size_t sum_marks_pk = total_marks_pk;
    for (const auto & stat : result.index_stats)
        if (stat.type == IndexType::PrimaryKey)
            sum_marks_pk = stat.num_granules_after;

    size_t sum_marks = 0;
    size_t sum_ranges = 0;
    size_t sum_rows = 0;

    for (const auto & part : result.parts_with_ranges)
    {
        sum_ranges += part.ranges.size();
        sum_marks += part.getMarksCount();
        sum_rows += part.getRowsCount();
    }

    result.total_parts = total_parts;
    result.parts_before_pk = parts_before_pk;
    result.selected_parts = result.parts_with_ranges.size();
    result.selected_ranges = sum_ranges;
    result.selected_marks = sum_marks;
    result.selected_marks_pk = sum_marks_pk;
    result.total_marks_pk = total_marks_pk;
    result.selected_rows = sum_rows;

    const auto & input_order_info = query_info.getInputOrderInfo();
    if ((settings.optimize_read_in_order || settings.optimize_aggregation_in_order) && input_order_info)
        result.read_type = (input_order_info->direction > 0) ? ReadType::InOrder
                                                             : ReadType::InReverseOrder;

    return std::make_shared<MergeTreeDataSelectAnalysisResult>(MergeTreeDataSelectAnalysisResult{.result = std::move(result)});
}

void ReadFromMergeTree::setQueryInfoOrderOptimizer(std::shared_ptr<ReadInOrderOptimizer> order_optimizer)
{
    if (query_info.projection)
    {
        query_info.projection->order_optimizer = order_optimizer;
    }
    else
    {
        query_info.order_optimizer = order_optimizer;
    }
}

void ReadFromMergeTree::setQueryInfoInputOrderInfo(InputOrderInfoPtr order_info)
{
    if (query_info.projection)
    {
        query_info.projection->input_order_info = order_info;
    }
    else
    {
        query_info.input_order_info = order_info;
    }
}

ReadFromMergeTree::AnalysisResult ReadFromMergeTree::getAnalysisResult() const
{
    auto result_ptr = analyzed_result_ptr ? analyzed_result_ptr : selectRangesToRead(prepared_parts);
    if (std::holds_alternative<std::exception_ptr>(result_ptr->result))
        std::rethrow_exception(std::get<std::exception_ptr>(result_ptr->result));

    return std::get<ReadFromMergeTree::AnalysisResult>(result_ptr->result);
}

void ReadFromMergeTree::initializePipeline(QueryPipelineBuilder & pipeline, const BuildQueryPipelineSettings &)
{
    auto result = getAnalysisResult();
    LOG_DEBUG(
        log,
        "Selected {}/{} parts by partition key, {} parts by primary key, {}/{} marks by primary key, {} marks to read from {} ranges",
        result.parts_before_pk,
        result.total_parts,
        result.selected_parts,
        result.selected_marks_pk,
        result.total_marks_pk,
        result.selected_marks,
        result.selected_ranges);

    ProfileEvents::increment(ProfileEvents::SelectedParts, result.selected_parts);
    ProfileEvents::increment(ProfileEvents::SelectedRanges, result.selected_ranges);
    ProfileEvents::increment(ProfileEvents::SelectedMarks, result.selected_marks);

    auto query_id_holder = MergeTreeDataSelectExecutor::checkLimits(data, result, context);

    if (result.parts_with_ranges.empty())
    {
        pipeline.init(Pipe(std::make_shared<NullSource>(getOutputStream().header)));
        return;
    }

    selected_marks = result.selected_marks;
    selected_rows = result.selected_rows;
    selected_parts = result.selected_parts;
    /// Projection, that needed to drop columns, which have appeared by execution
    /// of some extra expressions, and to allow execute the same expressions later.
    /// NOTE: It may lead to double computation of expressions.
    ActionsDAGPtr result_projection;

    Names column_names_to_read = std::move(result.column_names_to_read);
    const auto & select = query_info.query->as<ASTSelectQuery &>();
    if (!select.final() && result.sampling.use_sampling)
    {
        /// Add columns needed for `sample_by_ast` to `column_names_to_read`.
        /// Skip this if final was used, because such columns were already added from PK.
        std::vector<String> add_columns = result.sampling.filter_expression->getRequiredColumns().getNames();
        column_names_to_read.insert(column_names_to_read.end(), add_columns.begin(), add_columns.end());
        ::sort(column_names_to_read.begin(), column_names_to_read.end());
        column_names_to_read.erase(std::unique(column_names_to_read.begin(), column_names_to_read.end()),
                                   column_names_to_read.end());
    }

    Pipe pipe;

    const auto & settings = context->getSettingsRef();
    const auto & input_order_info = query_info.getInputOrderInfo();

    if (select.final())
    {
        /// Add columns needed to calculate the sorting expression and the sign.
        std::vector<String> add_columns = metadata_for_reading->getColumnsRequiredForSortingKey();
        column_names_to_read.insert(column_names_to_read.end(), add_columns.begin(), add_columns.end());

        if (!data.merging_params.sign_column.empty())
            column_names_to_read.push_back(data.merging_params.sign_column);
        if (!data.merging_params.version_column.empty())
            column_names_to_read.push_back(data.merging_params.version_column);

        ::sort(column_names_to_read.begin(), column_names_to_read.end());
        column_names_to_read.erase(std::unique(column_names_to_read.begin(), column_names_to_read.end()), column_names_to_read.end());

        pipe = spreadMarkRangesAmongStreamsFinal(
            std::move(result.parts_with_ranges),
            column_names_to_read,
            result_projection);
    }
    else if ((settings.optimize_read_in_order || settings.optimize_aggregation_in_order || settings.optimize_read_in_window_order) && input_order_info)
    {
        pipe = spreadMarkRangesAmongStreamsWithOrder(
            std::move(result.parts_with_ranges),
            column_names_to_read,
            result_projection,
            input_order_info);
    }
    else
    {
        pipe = spreadMarkRangesAmongStreams(
            std::move(result.parts_with_ranges),
            column_names_to_read);
    }

    for (const auto & processor : pipe.getProcessors())
        processor->setStorageLimits(query_info.storage_limits);

    if (pipe.empty())
    {
        pipeline.init(Pipe(std::make_shared<NullSource>(getOutputStream().header)));
        return;
    }

    if (result.sampling.use_sampling)
    {
        auto sampling_actions = std::make_shared<ExpressionActions>(result.sampling.filter_expression);
        pipe.addSimpleTransform([&](const Block & header)
        {
            return std::make_shared<FilterTransform>(
                header,
                sampling_actions,
                result.sampling.filter_function->getColumnName(),
                false);
        });
    }

    Block cur_header = pipe.getHeader();

    auto append_actions = [&result_projection](ActionsDAGPtr actions)
    {
        if (!result_projection)
            result_projection = std::move(actions);
        else
            result_projection = ActionsDAG::merge(std::move(*result_projection), std::move(*actions));
    };

    /// By the way, if a distributed query or query to a Merge table is made, then the `_sample_factor` column can have different values.
    if (sample_factor_column_queried)
    {
        ColumnWithTypeAndName column;
        column.name = "_sample_factor";
        column.type = std::make_shared<DataTypeFloat64>();
        column.column = column.type->createColumnConst(0, Field(result.sampling.used_sample_factor));

        auto adding_column = ActionsDAG::makeAddingColumnActions(std::move(column));
        append_actions(std::move(adding_column));
    }

    if (result_projection)
        cur_header = result_projection->updateHeader(cur_header);

    /// Extra columns may be returned (for example, if sampling is used).
    /// Convert pipe to step header structure.
    if (!isCompatibleHeader(cur_header, getOutputStream().header))
    {
        auto converting = ActionsDAG::makeConvertingActions(
            cur_header.getColumnsWithTypeAndName(),
            getOutputStream().header.getColumnsWithTypeAndName(),
            ActionsDAG::MatchColumnsMode::Name);

        append_actions(std::move(converting));
    }

    if (result_projection)
    {
        auto projection_actions = std::make_shared<ExpressionActions>(result_projection);
        pipe.addSimpleTransform([&](const Block & header)
        {
            return std::make_shared<ExpressionTransform>(header, projection_actions);
        });
    }

    for (const auto & processor : pipe.getProcessors())
        processors.emplace_back(processor);


    pipeline.init(std::move(pipe));
    // Attach QueryIdHolder if needed
    if (query_id_holder)
        pipeline.setQueryIdHolder(std::move(query_id_holder));
}

static const char * indexTypeToString(ReadFromMergeTree::IndexType type)
{
    switch (type)
    {
        case ReadFromMergeTree::IndexType::None:
            return "None";
        case ReadFromMergeTree::IndexType::MinMax:
            return "MinMax";
        case ReadFromMergeTree::IndexType::Partition:
            return "Partition";
        case ReadFromMergeTree::IndexType::PrimaryKey:
            return "PrimaryKey";
        case ReadFromMergeTree::IndexType::Skip:
            return "Skip";
    }

    __builtin_unreachable();
}

static const char * readTypeToString(ReadFromMergeTree::ReadType type)
{
    switch (type)
    {
        case ReadFromMergeTree::ReadType::Default:
            return "Default";
        case ReadFromMergeTree::ReadType::InOrder:
            return "InOrder";
        case ReadFromMergeTree::ReadType::InReverseOrder:
            return "InReverseOrder";
    }

    __builtin_unreachable();
}

void ReadFromMergeTree::describeActions(FormatSettings & format_settings) const
{
    auto result = getAnalysisResult();
    std::string prefix(format_settings.offset, format_settings.indent_char);
    format_settings.out << prefix << "ReadType: " << readTypeToString(result.read_type) << '\n';

    if (!result.index_stats.empty())
    {
        format_settings.out << prefix << "Parts: " << result.index_stats.back().num_parts_after << '\n';
        format_settings.out << prefix << "Granules: " << result.index_stats.back().num_granules_after << '\n';
    }
}

void ReadFromMergeTree::describeActions(JSONBuilder::JSONMap & map) const
{
    auto result = getAnalysisResult();
    map.add("Read Type", readTypeToString(result.read_type));
    if (!result.index_stats.empty())
    {
        map.add("Parts", result.index_stats.back().num_parts_after);
        map.add("Granules", result.index_stats.back().num_granules_after);
    }
}

void ReadFromMergeTree::describeIndexes(FormatSettings & format_settings) const
{
    auto result = getAnalysisResult();
    auto index_stats = std::move(result.index_stats);

    std::string prefix(format_settings.offset, format_settings.indent_char);
    if (!index_stats.empty())
    {
        /// Do not print anything if no indexes is applied.
        if (index_stats.size() == 1 && index_stats.front().type == IndexType::None)
            return;

        std::string indent(format_settings.indent, format_settings.indent_char);
        format_settings.out << prefix << "Indexes:\n";

        for (size_t i = 0; i < index_stats.size(); ++i)
        {
            const auto & stat = index_stats[i];
            if (stat.type == IndexType::None)
                continue;

            format_settings.out << prefix << indent << indexTypeToString(stat.type) << '\n';

            if (!stat.name.empty())
                format_settings.out << prefix << indent << indent << "Name: " << stat.name << '\n';

            if (!stat.description.empty())
                format_settings.out << prefix << indent << indent << "Description: " << stat.description << '\n';

            if (!stat.used_keys.empty())
            {
                format_settings.out << prefix << indent << indent << "Keys: " << stat.name << '\n';
                for (const auto & used_key : stat.used_keys)
                    format_settings.out << prefix << indent << indent << indent << used_key << '\n';
            }

            if (!stat.condition.empty())
                format_settings.out << prefix << indent << indent << "Condition: " << stat.condition << '\n';

            format_settings.out << prefix << indent << indent << "Parts: " << stat.num_parts_after;
            if (i)
                format_settings.out << '/' << index_stats[i - 1].num_parts_after;
            format_settings.out << '\n';

            format_settings.out << prefix << indent << indent << "Granules: " << stat.num_granules_after;
            if (i)
                format_settings.out << '/' << index_stats[i - 1].num_granules_after;
            format_settings.out << '\n';
        }
    }
}

void ReadFromMergeTree::describeIndexes(JSONBuilder::JSONMap & map) const
{
    auto result = getAnalysisResult();
    auto index_stats = std::move(result.index_stats);

    if (!index_stats.empty())
    {
        /// Do not print anything if no indexes is applied.
        if (index_stats.size() == 1 && index_stats.front().type == IndexType::None)
            return;

        auto indexes_array = std::make_unique<JSONBuilder::JSONArray>();

        for (size_t i = 0; i < index_stats.size(); ++i)
        {
            const auto & stat = index_stats[i];
            if (stat.type == IndexType::None)
                continue;

            auto index_map = std::make_unique<JSONBuilder::JSONMap>();

            index_map->add("Type", indexTypeToString(stat.type));

            if (!stat.name.empty())
                index_map->add("Name", stat.name);

            if (!stat.description.empty())
                index_map->add("Description", stat.description);

            if (!stat.used_keys.empty())
            {
                auto keys_array = std::make_unique<JSONBuilder::JSONArray>();

                for (const auto & used_key : stat.used_keys)
                    keys_array->add(used_key);

                index_map->add("Keys", std::move(keys_array));
            }

            if (!stat.condition.empty())
                index_map->add("Condition", stat.condition);

            if (i)
                index_map->add("Initial Parts", index_stats[i - 1].num_parts_after);
            index_map->add("Selected Parts", stat.num_parts_after);

            if (i)
                index_map->add("Initial Granules", index_stats[i - 1].num_granules_after);
            index_map->add("Selected Granules", stat.num_granules_after);

            indexes_array->add(std::move(index_map));
        }

        map.add("Indexes", std::move(indexes_array));
    }
}

bool MergeTreeDataSelectAnalysisResult::error() const
{
    return std::holds_alternative<std::exception_ptr>(result);
}

size_t MergeTreeDataSelectAnalysisResult::marks() const
{
    if (std::holds_alternative<std::exception_ptr>(result))
        std::rethrow_exception(std::get<std::exception_ptr>(result));

    const auto & index_stats = std::get<ReadFromMergeTree::AnalysisResult>(result).index_stats;
    if (index_stats.empty())
        return 0;
    return index_stats.back().num_granules_after;
}

}