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. 

{
    LogEntryPtr & entry = selected_entry->log_entry;
    return queue.processEntry([this]{ return getZooKeeper(); }, entry, [&](LogEntryPtr & entry_to_process)
    {
        try
        {
            return executeLogEntry(*entry_to_process);
        }
        catch (const Exception & e)
        {
            if (e.code() == ErrorCodes::NO_REPLICA_HAS_PART)
            {
                
                LOG_INFO(log, fmt::runtime(e.displayText()));
            }
            else if (e.code() == ErrorCodes::ABORTED)
            {
                
                LOG_INFO(log, fmt::runtime(e.message()));
            }
            else if (e.code() == ErrorCodes::PART_IS_TEMPORARILY_LOCKED)
            {
                
                LOG_INFO(log, fmt::runtime(e.displayText()));