ClickHouse/dbms/src/Storages/MergeTree/MergeTreeReaderStream.h

#include <Storages/MarkCache.h>
#include <Storages/MergeTree/MarkRange.h>
#include <Storages/MergeTree/MergeTreeData.h>
#include <Storages/MergeTree/MergeTreeRangeReader.h>
#include <Storages/MergeTree/MergeTreeIndexGranularityInfo.h>
#include <Compression/CachedCompressedReadBuffer.h>
#include <Compression/CompressedReadBufferFromFile.h>
#include <Storages/MergeTree/MergeTreeReaderSettings.h>
#include <Storages/MergeTree/MergeTreeMarksLoader.h>


namespace DB
{

/// Class for reading a single column (or index).
class MergeTreeReaderStream
{
public:
    enum class ReadingMode
    {
        COLUMN,
        INDEX,
    };

    MergeTreeReaderStream(
            const String & path_prefix_, const String & data_file_extension_, size_t marks_count_,
            const MarkRanges & all_mark_ranges,
            const ReaderSettings & settings_,
            MarkCache * mark_cache, UncompressedCache * uncompressed_cache,
            size_t file_size, const MergeTreeIndexGranularityInfo * index_granularity_info_,
            ReadingMode mode_,
            const ReadBufferFromFileBase::ProfileCallback & profile_callback, clockid_t clock_type);

    void seekToMark(size_t index);

    void seekToStart();

    ReadBuffer * data_buffer;

private:
    void initMarksLoader();

    std::string path_prefix;
    std::string data_file_extension;

    size_t marks_count;

    MarkCache * mark_cache;
    bool save_marks_in_cache;

    const MergeTreeIndexGranularityInfo * index_granularity_info;
    ReadingMode mode;

    std::unique_ptr<CachedCompressedReadBuffer> cached_buffer;
    std::unique_ptr<CompressedReadBufferFromFile> non_cached_buffer;

    MergeTreeMarksLoader marks_loader;
};
}