52.8. pg_group
  The view
  
   pg_group
  
  exists for backwards
   compatibility: it emulates a catalog that existed in
  
   PostgreSQL
  
  before version 8.1.
   It shows the names and members of all roles that are marked as not
  
   rolcanlogin
  
  , which is an approximation to the set
   of roles that are being used as groups.
 
   
    Table 52.8. 
    
     pg_group
    
    Columns