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. 

throw Exception(ErrorCodes::PART_IS_TEMPORARILY_LOCKED, out_reason);
            return false;
        }
        if (merge_pred.partParticipatesInReplaceRange(part, &out_reason))
        {
            if (throw_if_noop)
                throw Exception(ErrorCodes::PART_IS_TEMPORARILY_LOCKED, out_reason);
            return false;
        }
        if (partIsLastQuorumPart(part->info))
        {
            if (throw_if_noop)
                throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Part {} is last inserted part with quorum in partition. Cannot drop", part_name);
            return false;
        }
        if (partIsInsertingWithParallelQuorum(part->info))
        {
            if (throw_if_noop)
                throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Part {} is inserting with parallel quorum. Cannot drop", part_name);
            return false;
        }
        Coordination::Requests ops;
        getClearBlocksInPartitionOps(ops, *zookeeper, part_info.partition_id, part_info.min_block, part_info.max_block);
        size_t clear_block_ops_size = ops.size();
        
        
        entry.type = LogEntry::DROP_RANGE;
        entry.source_replica = replica_name;