The figure represents the vertical storage model, in which there is a physical table corresponding to each view in the hierarchy, but each physical table stores only those attributes that are unique to its corresponding subtype.
In this illustration, the tables are all_personattrs
, all_studentattrs
, and all_employeeattrs
. These tables contain the attributes for the person (ssn
, name
, and address
), student (deptid
and major
), and employee (empid
and mgr
) types respectively.
The Person_v
view is based on the all_personattrs
table, the Student_v
view is based on the all_studentattrs
table, and the Employee_v
view is based on the all_employeeattrs
table.