ON THE MEMORY MANAGEMENT, THE NESTED MODEL AND MULTIMEDIA IN A CAD DATABASE MANAGEMENT SYSTEM

摘要

This paper discusses the framework of an engineering database management system-EDBMS/3 and several key techniques in the implementation of the system. Based on extending and modifying EDBMS/2 which is designed and implemented by CAD Laboratory of the Institute of Computer Technology, Academia Sinica, EDBMS/3 supplies stronger capacity of Data Definition Language (DDL) and Data Manipulation Language (DML). The multi-table scheduler in memory management supports both user and system scheduling. In the former, the user can specify their operations in table working areas, while in the latter the system manages the table working areas automatically. The paper defines an nested table network structure in a multi-table environment to prevent possible system errors and data inconsistency occuring. The operations of denning and manipulating multimedia data, means the system must have the ability to process dynamic multimedia data such as a period of sound or a section of an image.