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. 

String index_path_in_backup = data_path_in_backup_fs / fileName(index_file_path);
            IndexForNativeFormat extra_indices;
            if (!backup->fileExists(index_path_in_backup))
                throw Exception(ErrorCodes::CANNOT_RESTORE_TABLE, "File {} in backup is required to restore table", index_path_in_backup);
            auto backup_entry = backup->readFile(index_path_in_backup);
            auto index_in = backup_entry->getReadBuffer();
            CompressedReadBuffer index_compressed_in{*index_in};
            extra_indices.read(index_compressed_in);
            
            for (auto & block : extra_indices.blocks)
            {
                for (auto & column : block.columns)
                    column.location.offset_in_compressed_file += old_data_size;
            }
            insertAtEnd(indices.blocks, std::move(extra_indices.blocks));
        }
        
        saveIndices(lock);
        saveFileSizes(lock);
        updateTotalRows(lock);
    }
    catch (...)
    {
        
        file_checker.repair();
        removeUnsavedIndices(lock);
        throw;
    }
}
void registerStorageStripeLog(StorageFactory & factory)