DBC Software Requirements for Supporting Hierarchical Databases.

摘要

This report shows the capability of the database computer (DBC) for supporting hierarchical data models and systems. Since IBM's Information Management System (IMS) is the most widely used data management system which supports a hierarchical view of data, we intend to show that the DBC can support IMS databases and IMS application programs. Furthermore, this study provides us with a case for comparing the merits of using a conventional general-purpose computer versus a special-purpose database computer (i.e., the DBC) for data management. It is shown that it is possible to design an interface, known as IMSI between IMS users and the DBC. The IMSI can faithfully execute the DL/1 calls (the data manipulation language of IMS) issued by IMS users. The design of the IMSI is considered in two phases. In the first phase, we show how to represent an IMS database utilizing the built-in (hardware) data structure of the DBC. This representation makes use of the concept of embedding symbolic identifiers into all dependent segments of an IMS database. The use of symbolic identifiers increases the degree of data independence of the stored database. Furthermore, the storage requirement for the symbolic identifiers is substantially offset by the removal of the conventional address pointers currently used in an IMS database.