I am reading clickhouse mutation code. In StorageMergeTree->selectPartsToMutate() function, there is a check 
`if (current_ast_elements + commands_size >= max_ast_elements)
                break;`

I think if there are many mutations then the check result will be true, so that it will skip the remaining mutations.
But the new part's mutation is set to the last one in mutation map, and it does not apply the remaining mutations actually.
`new_part_info.mutation = current_mutations_by_version.rbegin()->first;`

Then the new part will miss the remaining mutations in future mutation job.

I think it's wrong here. Am I right?

If it is right, I will submit a PR 

{
    BackupEntries backup_entries;
    std::map<DiskPtr, std::shared_ptr<TemporaryFileOnDisk>> temp_dirs;
    for (const auto & part : data_parts)
    {
        auto disk = part->volume->getDisk();
        auto temp_dir_it = temp_dirs.find(disk);
        if (temp_dir_it == temp_dirs.end())
            temp_dir_it = temp_dirs.emplace(disk, std::make_shared<TemporaryFileOnDisk>(disk, "tmp/backup_")).first;
        auto temp_dir_owner = temp_dir_it->second;
        fs::path temp_dir = temp_dir_owner->getPath();
        fs::path part_dir = part->getFullRelativePath();
        fs::path temp_part_dir = temp_dir / part->relative_path;
        disk->createDirectories(temp_part_dir);
        for (const auto & [filepath, checksum] : part->checksums.files)
        {
            String relative_filepath = fs::path(part->relative_path) / filepath;
            String hardlink_filepath = temp_part_dir / filepath;
            disk->createHardLink(part_dir / filepath, hardlink_filepath);
            UInt128 file_hash{checksum.file_hash.first, checksum.file_hash.second};
            backup_entries.emplace_back(
                relative_filepath,