Reading https://ec.europa.eu/info/law/law-topic/data-protection/reform/what-personal-data_en https://ec.europa.eu/info/law/law-topic/data-protection/refo... I w

Reading https://ec.europa.eu/info/law/law-topic/data-protection/reform/what-personal-data_en https://ec.europa.eu/info/law/law-topic/data-protection/refo... I would agree, of course if that identifier is not in some other database, that maps it to a person. If you have just ids in a backup and you remove the person-ID mapping this should be fine.