Optimizing fragment constraints

H. Ibrahim et al. (1997) introduced an integrity constraint subsystem for a relational distributed database (SICSDD) that they developed. The subsystem consists of several techniques which are necessary for efficient constraint checking, particularly for a distributed environment where data distribution is transparent to the application domain. We show how these techniques have effectively reduced the cost of constraint checking in such a distributed environment. This is performed by analysing and comparing the generated simplified forms to their respective initial constraints with respect to the amount of data that has to be accessed, the amount of data transferred across the network and the number of sites that may be involved during the evaluation of these constraints/simplified forms