
28 1.2 Data Modeling for Data Warehouses
shown in Figure 1.18. This will allow access to all details of a multiple hier-
archical dimension in all forms.
Referential Integrity
This chapter has already described referential integrity in data warehouses.
Further comment is necessary. Many data warehouses probably do not have
referential integrity implemented at all. If implementing referential integ-
rity, use constraints. If creating foreign key constraints, indexing those for-
eign keys might be sensible, especially if dimension entity primary key
values are to be updated or deleted. Whatever you do, never use triggers.
Triggers are ten times slower than ...