Design of relational views over network schemas

ABSTRACT

An algorithm is presented for designing relational views over network schemas to: (1) support general query and update capability, (2) preserve the information content of the data base and (3) provide independence from its physical organization. The proposed solution is applicable to many existing CODASYL databases without data or schema conversion. The particular declarations of a CODASYL schema which supply sources of logical data definition are first identified. Then the view design algorithm is derived on the basis of a formal analysis of the semantic constraints established by these declarations. A new form of data structure diagram is also introduced to visualize these constraints.

REFERENCES

• 1: CODA 73 "CODASYL Data Description Language Journal of Development, June 1973," NBS Handbook 113.
• 2: CODA 78 "CODASYL 78 Data Description Language Journal of Development, January 1978," Information Systems, Vol. 3, No. 4, 1978.
• 3: CODD 72 Codd, E. F. "Further Normalization of the Data base Relational Model," Database Systems, Courant Computer Science Series, Vol. 6, Prentice Hall, New York, 1972.
• 4: C.J. J. Date, An Introduction to Database Systems, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 1981
• 5: DAYA 78 Dayal, U. and P. Bernstein, "On the Updatability of Relational Views," Very Large Data Base Conference, Sept. 13--15, 1978, West Berlin, Germany.
• 6: Ronald Fagin, Multivalued dependencies and a new normal form for relational databases, ACM Transactions on Database Systems (TODS), v.2 n.3, p.262-278, Sept. 1977 [doi>10.1145/320557.320571]
• 7: GOLD 79 Goldman, J. "Automated Generation of Relational Schemas for CODASYL Databases," Sperry Research Center Research Paper SCRC-RR-79-13, March 79 (submitted to VLDB '79).
• 8: JOHN 78 Johnson H. R., Larson J. A. and J. D. Lawrence, "A Common Data Base Architecture," IEEE Workshop on Data Management and Storage Hierarchies, Sept. 6--8 1978, Lake Arrowhead, California.
• 9: SEVC 78 Sevcik, K. C. and A. L. Futardo "Complete and Compatible Sets of Update Operations," Proceedings of the ICMOD 78 Conference on DBMS, June 29--30 1978, Milan, Italy.
• 10: John Miles Smith , Diane C. P. Smith, Database abstractions: aggregation, Communications of the ACM, v.20 n.6, p.405-413, June 1977 [doi>10.1145/359605.359620]
• 11: ZANI 77 Zaniolo, C. "Relational Views in Data Base Systems: Support for Queries," COMPSAC77, November 8--11, 1977, Chicago, Illinois.
• 12: ZANI 78 Zaniolo, C. "Relational Views over a Network Schema," Sperry Research Center Report, SCRC-RR-78-37, July 1978.
• 13: ZANI 79 Zaniolo, C. "Multimodel External Schemas for CODASYL Data Base Management Systems," IFIP TC-2 Working Conference on Data Base Architecture June 26--29, 1979, Venice, Italy (North Holland).