As pointed out at the beginning of this chapter, there are a number of benefits to constraints and referential integrity. They are easy to configure, all client applications must abide by them, and they can improve the overall integrity of your data.
But the ease with which constraints can be added to a data dictionary can lead to their overuse. When overused, they can prevent valid data from being entered into your database. And in the case of referential integrity constraints, they can produce an unexpected increase in resource use on the server.
The following sections take a final look at each of the types of constraints provided by a data dictionary. In each case, the limits of each approach are discussed.