The present invention relates to a database management system, and in particular, to an object-oriented database management system employing an object identifier to increase the data access speed of the database.
As described on pages 760 to 768 of the "Transaction Processing: Concepts And Techniques" written by Jim Gray and Andreas Reuter and published from Morgan Kaufmann Publishers in 1993, there have been heretofore known two object management methods in the database management systems. In the first method, storage position information of each object is adopted as an object identifier for the object management, and in the second method, a generation serial number of each object is utilized as an object identifier, and there is provided a translation table for relating each object identifier to an object storage information item to manage the objects.
According to the first method of the database management system, there arises a problem for the preservation of uniqueness, integrity, and perpetuity of each object identifier thus generated. Namely, the user cannot store a new object at a storage area in which the preceding object has already been deleted unless the user re-arranges the objects in the database and changes the contents of pointers pointing to those objects. In other words, the storage position of an object once stored to the database cannot be altered unless the user changes the contents of pointers pointing to the object.
On the other hand, according to the second object management method, the translation table is implemented employing an index system in which the object identifier is set as an index key. Consequently, in the generation and/or deletion of the object or in the handling of the object using an object identifier, there occurs overhead time in various processing operations such as retrieval and update of the index above. This results in a problem of deterioration in the processing performance of the database management system.