Abstract
The Internet has provided users with access to wealth of information available on the Web, a considerable amount of which is semi-structured. In recent times, there has grown a need to access this information in an interpretable and meaningful way. One way to access this information is by transforming it into relations and integrating the relations to arrive at a universal relation thus ensuring simple and powerful searching of the underlying semi-structured data. Several operations exist for integrating these relations, like outer union, natural inner join, natural outer join etc., of which natural outer join has been found to be most effective in terms of achieving meaningful results i.e. full disjunction of the relations. Since natural outer join is non-associative, for more than two relations only some of the natural outer join ordering may lead to full disjunction. The Correct Outer Join Ordering (COJO) strategy proposed in this paper computes such natural outer join ordering of relations leading to full disjunction. It is further shown that the natural outer join ordering of relations produced by algorithm COJO compares well with the well-known algorithm SOJO on performance parameters.
Similar content being viewed by others
References
C. Beeri, R. Fagin, D. Maier, M. Yannakakis, On the desirability of acyclic database schemes. J. Assoc. Comput. Mach. 30(3), 479–513 (1983)
S. Chawathe, H. Garcia-Molina, J. Hammer, K. Ireland, Y. Papakonstantinou, J. Ullman, J. Widom, The TSIMMIS Project: integration of heterogeneous information sources, in 16th Meeting of the Information Processing Society of Japan (IPSJ), Tokyo, Japan, October, 1994, pp. 7–18
S. Cohen, I. Fadida, Y. Kanza, B. Kimelfeld, Y. Sagiv, Full disjunctions: polynomial-delay iterators in action, in Proceedings of the 32nd International Conference on Very Large Data Bases, Seoul, South Korea, VLDB 2006, pp. 739–750
S. Cohen, Y. Kanza, Y. Sagiv, Generating relations from XML documents, in 9th International Conference on Database Theory (ICDT), January, 2003
S. Cohen, Y. Sagiv, An incremental algorithm for computing ranked full disjunctions, in Proceedings of the 24th ACM Symposium on Principles of Database Systems (PODS), Baltimore, Maryland, 2005
S. Cohen, Y. Sagiv, An incremental algorithm for computing ranked full disjunctions. J. Comput. Syst. Sci. 73(4), 648–668 (2007)
C.J. Date, The outer join, in Proceedings of the 2nd International Conference on Databases, Cambridge, England, 1983
C.J. Date, An Introduction to Database Systems, 8th edn. (Addison Wesley, 2003), pp. 1024
M.M. David, Advanced capabilities of the outer join. ACM SIGMOD RECORD 21(1), 65–70 (1992). doi:10.1145/130868.133746
R. Fagin, Degree of acyclicity for hypergraphs and relational database schemes. J. ACM 7(3), 343–360 (1983)
R. Fagin, A.O. Mendelzon, J.D. Ullman, A simplified universal relation assumption and its properties. ACM Trans. Database Syst. 7(3), 343–360 (1982). doi:10.1145/319732.319735
C.A. Galindo-Legaria, Outerjoins as disjunctions, in Proceedings of the ACM-SIGMOD International Conference on Management of Data, Minneapolis, USA, 1994, pp. 348–358
T. Gruber, A translation approach to portable ontology specifications. Knowl. Acquis. 5(2), 199–220 (1993). doi:10.1006/knac.1993.1008
Y. Kanza, Oblivious queries over data with irregular structure, Ph.D. thesis, Hebrew University, 2004, pp. 181 (pp. 133)
Y. Kanza, Y. Sagiv, Computing full disjunctions, PODS, June 9–12, San Diego, 2003, pp. 78–89
B.S. Lee, G. Wiederhold, Outer joins and filters for instantiating objects from relational databases through views. IEEE Trans. Knowl. Data Eng. 6(1), 108–119 (1994). doi:10.1109/69.273036
D. Maier, J.D. Ullman, M.Y. Vardi, On the foundation of the Universal Relation Model. ACM Trans. Database Syst. 9(2), 283–308 (1984). doi:10.1145/329.318580
K. Munakata, Integration of maximum information using outerjoins, predicates and foreign functions, in IEICE Trans. Inf. & Syst., E82-D(1), 1999
Y. Papakonstantinou, H. Garcia-Molina, J. Widom, Object exchange across heterogeneous information sources, in Proceedings of the IEEE Intl Conference on Data Engineering (ICDE), 1995
A. Rajaraman, J.D. Ullman, Integrating information by outerjoins and full disjunctions, PODS, 1996, pp. 238–248
J. Shanmugasundaram, K. Tufte, C. Zhang, G. He, D.J. DeWitt, J.F. Naughton, Relational databases for querying XML documents: limitations and opportunities. VLDB, Morgan-Kauffman, 1999, pp. 302–314
P.S.M. Tsai, A.L.P. Chen, Partial natural outer join-an operation for interoperability in a multidatabase environment. J. Inf. Sci. Eng. 16, 593–617 (2000)
J.D. Ullman, Principles of Database and Knowledge-Base Systems, Vol. II: The New Technologies (Computer Science Press, New York)
T.V. Vijay Kumar, A. Shridhar, Integrating maximum information using COJO, in Proceedings of the International Conference on Information Systems, Technology and Management (ICISTM-2007), March 12–13, New Delhi, 2007, pp. 39–47
Author information
Authors and Affiliations
Corresponding author
Additional information
This paper is an expanded version of [24].
Rights and permissions
About this article
Cite this article
Vijay Kumar, T.V., Shridhar, A. & Ghoshal, A. Computing full disjunction using COJO. Inf Technol Manag 10, 3–20 (2009). https://doi.org/10.1007/s10799-008-0043-0
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10799-008-0043-0