Please note: eZ Survey will loose results when archived versions of the survey is deleted. The workaround is to increase the number of archived versions the system will store for survey objects (you need to configure this manually if you have survey classes with custom names (where class identifier != 'survey' ).

Running the flatten.php script, or a cronjob which implements it, will cause the archived versions of surveys to be deleted, so, please be sure to avoid running it.