COMPILED OBJECTIVE REFERENTIAL CONSTRAINTS IN A RELATIONAL DATA BASE MANAGEMENT SYSTEM

摘要

An implementation of referential integrity in which descriptions of referential constraints are compiled into meta-data descriptions of the constraint rules and specifications. The meta-data descriptions of the constraints are stored in the form of objects called relationship descriptors. Each relationship descriptor contains a complete description of a referential constraint, either directly or by means of pointers to other objects such a record and index descriptors which contain information comprised in the constraint's specification. The relationship descriptors are linked into two types of chains by symbolic pointers. One type of relationship descriptor chain connects all relationship descriptors which have a common parent table. The other type of relationship descriptor chain connects relationship descriptors with common dependent tables. Both types of chains are anchored in respective fields in the tables' record descriptors. The use of meta-data descriptors facilitates both ready modification of the constraints, and speedy enforcement of the constraints by a single, shared procedure which may be embedded in the data base manager.