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. 

}
                ops.emplace_back(zkutil::makeCreateRequest(zookeeper_node, "", mode));
                Coordination::Responses responses;
                auto error = zookeeper->tryMulti(ops, responses);
                if (error == Coordination::Error::ZOK || error == Coordination::Error::ZNODEEXISTS)
                {
                    created = true;
                    break;
                }
                else if (error == Coordination::Error::ZNONODE && mode != zkutil::CreateMode::Persistent)
                {
                    
                    throw Exception(ErrorCodes::NOT_FOUND_NODE, "Cannot create ephemeral zero copy lock {} because part was unlocked from zookeeper", zookeeper_node);
                }
            }
        }
        catch (const zkutil::KeeperException & e)
        {
            if (e.code == Coordination::Error::ZNONODE)
                continue;
            throw;
        }
    }
    if (!created)
    {
        String mode_str = mode == zkutil::CreateMode::Persistent ? "persistent" : "ephemral";
        throw Exception(ErrorCodes::NOT_FOUND_NODE, "Cannot create {} zero copy lock {} because part was unlocked from zookeeper", mode_str, zookeeper_node);
    }
}
bool StorageReplicatedMergeTree::removeDetachedPart(DiskPtr disk, const String & path, const String & part_name, bool is_freezed)