A program for storage allocation in DECSYSTEM-20's DBMS.
Tung-Sheng Lai · 1980
A PROGRAM FOR STORAGE ALLOCATION IN DECSYSTEM-20'S DBMS by Tung-Sheng Lai This thesis presents a computer package designed to help the data base designer in the proper storage for DECSYSTEM-2 0's Data Base Management System(DBMS). The DEC'S DBMS is based on the 1971 CODASYL Data Base Task Group(DBTG) proposal. Although the Schema Data Description Language(Schema DDL) had been defined in reasonable detail by the CODASYL committees, the Device Media Control Language(DMCL) was left out as this is dependent on the specifications required by the implementor. Although storage allocation is a very critical aspect in data base design, there is no systematic approach to it. Due to this fact, most of the data base designers arbitrarily assign storage much larger than is really needed for the data base. Obviously, this is not an economical approach. On the other hand, some data base designers simply ignore the storage considerations, and as a result, eventually face the situation of having to unload the data base to increase the storage, and/or rewrite some or all of the application programs. The computer package presented in this thesis is designed to help the data base designers allocate appropriate storage for future growth of existing applications and new applications. This package is a PASCAL program, composed of two parts, a parser and an interactive program. The first part is a parser, which reads the user's Schema DDL as input, examines the syntactical structure of the Schema DDL statements, and stores all the information that will be used in storage calculation. The interactive program helps the user to develop his DMCL statements by asking to provide more information about the data base and its usage in the future. Information on how to access this package for use is available from Division of Computing and Information Science.