Method readFile

src/Storages/MergeTree/IMergeTreeDataPart.cpp:3159–3171

}

std::unique_ptr<ReadBuffer> IMergeTreeDataPart::readFile(const String & file_name) const
{
    constexpr size_t size_hint = 4096; /// These files are small.
    auto read_settings = getReadSettings().adjustBufferSize(size_hint);
    /// Default read method is pread_threadpool, but there is not much point in it here.
    read_settings.local_fs_settings.method = LocalFSReadMethod::pread;
    auto res = getDataPartStorage().readFile(file_name, read_settings, size_hint);

    if (isCompressedFromFileName(file_name))
        return std::make_unique<CompressedReadBufferFromFile>(std::move(res));

    return res;
}

std::unique_ptr<ReadBuffer> IMergeTreeDataPart::readFileIfExists(const String & file_name) const
{