Often an individual using a database system to perform a function is just one of many people who are authorized to perform that function. Rather than granting the privileges necessary to perform the function to each person, the privileges can be granted to an AuthID associated with a group, known as a GroupID. A GroupID is a special identifier that can be assigned to one or more Primary AuthIDs. The privileges granted to the GroupID are available to every Primary AuthID to which the GroupID is assigned.
Individual users can still log in using their own Primary AuthID, but because they are members of a group (with specifically defined privileges), they also possess the group privileges. A Primary AuthID can be a member of several groups -- in which case the AuthID possesses the combination of privileges granted directly to the Primary AuthID, plus the privileges defined for each group to which the Primary AuthID belongs.
All GroupIDs are recorded in the SYSXDB.SYSACFGROUPS table in the SYSTEM location. The relationship between a Primary and GroupID is established in the SQL Wizard by making the Primary AuthID a member of the group. The concept of the GroupID in the XDB Server is analogous to the Secondary Authorization ID in DB2.