Method MergeTreeReaderWide

src/Storages/MergeTree/MergeTreeReaderWide.cpp:58–139

}

MergeTreeReaderWide::MergeTreeReaderWide(
    MergeTreeMetaBase::DataPartPtr data_part_,
    NamesAndTypesList columns_,
    const StorageMetadataPtr & metadata_snapshot_,
    UncompressedCache * uncompressed_cache_,
    MarkCache * mark_cache_,
    MarkRanges mark_ranges_,
    MergeTreeReaderSettings settings_,
    MergeTreeIndexExecutor * index_executor_,
    IMergeTreeDataPart::ValueSizeMap avg_value_size_hints_,
    const ReadBufferFromFileBase::ProfileCallback & profile_callback_,
    clockid_t clock_type_,
    bool create_streams_)
    : IMergeTreeReader(
        std::move(data_part_),
        std::move(columns_),
        metadata_snapshot_,
        uncompressed_cache_,
        std::move(mark_cache_),
        std::move(mark_ranges_),
        std::move(settings_),
        std::move(avg_value_size_hints_),
        index_executor_)
{
    if (!create_streams_)
    {
        return;
    }

    try
    {
        for (const NameAndTypePair & column : columns)
        {
            auto column_from_part = getColumnFromPart(column);
            if (column_from_part.type->isByteMap())
            {
                // Scan the directory to get all implicit columns(stream) for the map type
                const DataTypeMap & type_map = typeid_cast<const DataTypeMap &>(*column_from_part.type);

                String key_name;
                String impl_key_name;
                {
                    for (auto & file : data_part->getChecksums()->files)
                    {
                        // Try to get keys, and form the stream, its bin file name looks like "NAME__xxxxx.bin"
                        const String & file_name = file.first;
                        if (isMapImplicitDataFileNameNotBaseOfSpecialMapName(file_name, column.name))
                        {
                            key_name = parseKeyNameFromImplicitFileName(file_name, column.name);
                            impl_key_name = getImplicitColNameForMapKey(column.name, key_name);
                            // Special handing if implicit key is referenced too
                            if (columns.contains(impl_key_name))
                            {
                                dup_implicit_keys.insert(impl_key_name);
                            }

                            addByteMapStreams(
                                {impl_key_name, type_map.getValueTypeForImplicitColumn()}, column.name, profile_callback_, clock_type_);