Dynamic functional dependencies and database aging

A simple extension of the relational model is introduced to study the effects of dynamic constraints on database evolution. Both static and dynamic constraints are used in conjunction with the model. The static constraints considered here are functional dependencies (FDs). The dynamic constraints involve global updates and are restricted to certain analogs of FDs, called “dynamic” FDs. The results concern the effect of the dynamic constraints on the static constraints satisfied by the database in the course of time. The effect of the past history of the database on the static constraints is investigated using the notions of age and age closure. The connection between the static constraints and the potential future evolution of the database is briefly discussed using the notions of survivability and survivability closure.