Conversion technology, an assessment
ACM SIGMIS Database
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One of the fastest growing areas in computer science today is the development and application of data base management systems (DBMS). These systems collect and maintain data in user-specified relationships in support of various interrelated applications. They provide a high level interface between application programs and the actual data to isolate the user from such operations as physical I/O, buffering and pointer manipulation. As new DBMSs are being developed with greater capabilities and features, users of existing DBMSs may wish to convert their application programs and the data bases to operate on the new system software. If the up-grading decision is made, all of the data and all of the application programs must be migrated to the new DBMS. Migration of DBMS involves all aspects connected with the stored data. The schema of the data, the data definition language, the application procedures as well as the physical data items must be converted in some fashion so that the new DBMS functions as desired. Migration is an expensive undertaking especially if a different manufacturer's hardware is to be acquired. In the past when users converted from one file organization to another file organization (example: Honeywell's ISP to IBM's ISAM), specialized programs were written to translate the data between file systems. In addition, all the old application programs were re-written or modified so that they would operate on the new file organization. If you multiply an individual data processing shop's efforts to convert by the number of computer installations that undergo a system conversion, an enormous expense has been incurred. In the future, it is foreseeable that even greater expenses will be incurred in order to change from an existing DBMS to a new DBMS.