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. 

if (exists && queue_entry_str == entry_str)
        {
            queue_entry_to_wait_for = entry_name;
            break;
        }
        else if (!entry.log_entry_id.empty())
        {
            
            
            
            ReplicatedMergeTreeLogEntryData queue_entry = *ReplicatedMergeTreeLogEntry::parse(queue_entry_str, queue_entry_stat);
            if (entry.log_entry_id == queue_entry.log_entry_id)
            {
                queue_entry_to_wait_for = entry_name;
                break;
            }
        }
    }
    
    if (queue_entry_to_wait_for.empty())
    {
        LOG_DEBUG(log, "No corresponding node found. Assuming it has been already processed. Found {} nodes", queue_entries.size());
        return true;
    }
    LOG_DEBUG(log, "Waiting for {} to disappear from {} queue", queue_entry_to_wait_for, replica);
    
    String path_to_wait_on = fs::path(table_zookeeper_path) / "replicas" / replica / "queue" / queue_entry_to_wait_for;
    return getZooKeeper()->waitForDisappear(path_to_wait_on, stop_waiting);
}
void StorageReplicatedMergeTree::getStatus(Status & res, bool with_zk_fields)