How to find group membership for a specific user using DQL.
This can help is you change the service user running Documentum Content server:

Run below DQL in Administrator or dqMan :

select r_object_id,group_name as object_name,owner_name,group_class,description,’0000000000000000′ as i_folder_id,0 as r_runtime_state
FROM dm_group
where any users_names = ‘dmadmin’
  OR owner_name = ‘dmadmin’
  order by group_name