Ordinary database engine is deprecated but there is no simple mean to change database engine to Atomic for existing databases.

Possible options:
- ALTER DATABASE MODIFY ENGINE query.
- Flag that triggers migration at ClickHouse startup.

The latter should be easier to implement. 

{
    auto settings = getSettings();
    if (!disk || !disk->supportZeroCopyReplication() || !settings->allow_remote_fs_zero_copy_replication)
        return;
    zkutil::ZooKeeperPtr zookeeper = tryGetZooKeeper();
    if (!zookeeper)
        return;
    String id = part_id;
    boost::replace_all(id, "/", "_");
    Strings zc_zookeeper_paths = getZeroCopyPartPath(*getSettings(), toString(disk->getType()), getTableSharedID(),
        part_name, zookeeper_path);
    for (const auto & zc_zookeeper_path : zc_zookeeper_paths)
    {
        String zookeeper_node = fs::path(zc_zookeeper_path) / id / replica_name;
        LOG_TRACE(log, "Set zookeeper temporary ephemeral lock {}", zookeeper_node);
        createZeroCopyLockNode(zookeeper, zookeeper_node, zkutil::CreateMode::Ephemeral, false);
    }
}
void StorageReplicatedMergeTree::lockSharedData(const IMergeTreeDataPart & part, bool replace_existing_lock, std::optional<HardlinkedFiles> hardlinked_files) const