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 

throw Exception(
            "Could not clone and load part " + quoteString(src_part->getFullPath()) + " because disk does not belong to storage policy",
            ErrorCodes::BAD_ARGUMENTS);
    String dst_part_name = src_part->getNewName(dst_part_info);
    String tmp_dst_part_name = tmp_part_prefix + dst_part_name;
    auto reservation = reserveSpace(src_part->getBytesOnDisk(), src_part->volume->getDisk());
    auto disk = reservation->getDisk();
    String src_part_path = src_part->getFullRelativePath();
    String dst_part_path = relative_data_path + tmp_dst_part_name;
    if (disk->exists(dst_part_path))
        throw Exception("Part in " + fullPath(disk, dst_part_path) + " already exists", ErrorCodes::DIRECTORY_ALREADY_EXISTS);
    /
    if (auto src_part_in_memory = asInMemoryPart(src_part))
    {
        const auto & src_relative_data_path = src_part_in_memory->storage.relative_data_path;
        auto flushed_part_path = src_part_in_memory->getRelativePathForPrefix(tmp_part_prefix);
        src_part_in_memory->flushToDisk(src_relative_data_path, flushed_part_path, metadata_snapshot);
        src_part_path = fs::path(src_relative_data_path) / flushed_part_path / "";
    }
    LOG_DEBUG(log, "Cloning part {} to {}", fullPath(disk, src_part_path), fullPath(disk, dst_part_path));
    localBackup(disk, src_part_path, dst_part_path);
    disk->removeFileIfExists(fs::path(dst_part_path) / IMergeTreeDataPart::DELETE_ON_DESTROY_MARKER_FILE_NAME);
    auto single_disk_volume = std::make_shared<SingleDiskVolume>(disk->getName(), disk, 0);
    auto dst_data_part = createPart(dst_part_name, dst_part_info, single_disk_volume, tmp_dst_part_name);
    dst_data_part->is_temp = true;
    dst_data_part->loadColumnsChecksumsIndexes(require_part_metadata, true);
    dst_data_part->modification_time = disk->getLastModified(dst_part_path).epochTime();
    return dst_data_part;
}
String MergeTreeData::getFullPathOnDisk(const DiskPtr & disk) const