Treating hierarchical data structures in the SDC Time-Shared Data Management System (TDMS)

ABSTRACT

An important consideration in the design of programming systems for the management of large files of data is the method of treating hierarchical data (that is, data among which logical relationships exist at more than two levels). Recent systems have accomplished this by simply duplicating some essential item of data at several levels. Such duplication makes the storage of even small data bases inefficient; for large masses of data, storage becomes economically unfeasible. Other systems have provided the means to specify and construct hierarchies, but none have provided language that affords control over retrieval and output levels, and control over the scope of output. Within the Time-Shared Data Management System (TDMS), currently being produced at System Development Corporation, a method has been devised for maintaining hierarchical associations within logical entries of a data base. Basically, the technique permits the automatic association of related data through a device known as a repeating group. The term “repeating group” is not new, but the TDMS treatment of the repeating group concept is. This paper describes how this technique is implemented in the language and tables of TDMS.

REFERENCES

• 1: A H VORHAUS and R D WILLS The time-shared data management system: a new approach to data management SDC document SP-2747 13 February 1967
• 2: V L RAUCHER and H S SCHWIMMER The basic language specifications for TDMS SDC document TM.-3370/001/00 10 April 1967
• 3: E W FRANKS A data management system for time-shared file-processing using a cross-index file and self-defining entries AFIPS Conference Proceedings 1966 Vol 28 79-86 Also available as SDC document SP-2248 21 April 1966
• 4: E E GRANT and P A DeSIMONE The language specifications for the define operations of TDMS SDC document TM-3370/003/00 15 April 1967
• 5: V L RAUCHER The language specifications for the query operation of TDMS SDC document TM-3370/003/00 15 April 1967
• 6: W D WILLIAMS and P R BARTRAM COMPOSE/PRODUCE: A user-oriented report generator capability within the SDC time-shared data management system AFIPS Conference Proceedings Spring 1967. Also available as SDC document SP-2634 8 February 1967
• 7: W D CLIMENSON Annual review of information science and technology John Wiley & Sons New York, 1966 Vol I Chapter 5 File Organization and Search Techniques
• 8: J MINKER and J SABLE Annual Review of Information Science and Technology John Wiley & Sons New York, 1967 Vol II (in press) Chapter 5 File organization, maintenance and search of machine files

INDEX TERMS

Primary Classification:
  H. Information Systems
  H.2 DATABASE MANAGEMENT

Additional Classification:
  E. Data
  E.1 DATA STRUCTURES

General Terms:
Management