A Method for the Horizontal Partition of Object-Oriented Databases

The partitioning of related objects should be performed before clustering for an efficient access in object-oriented databases. In this paper, a partition of related objects in object-oriented databases is presented. All subclass nodes in a class inheritance hierarchy of a schema graph are condensed to a class node in the graph because the aggregation hierarchy has more influence on the partition than the class inheritance hierarchy. This reduced graph is called a condensed schema graph. A set function and an accessibility function are defined to characterize a maximal subset of related objects among the set of objects in a class. A set function maps a subset of the domain class objects to a subset of the range class objects. An accessibility function maps a subset of the objects of a class into a subset of the objects of the same class through a composition of set functions. A partition algorithm is derived to find the related objects of a condensed schema graph using accessibility functions and set functions. The existence of a maximal subset of the related objects in a class is proved to show the validity of the partition algorithm using the accessibility function.