An algorithm for answering queries efficiently using views
ADC '01 Proceedings of the 12th Australasian database conference
Rewriting general conjunctive queries using views
ADC '02 Proceedings of the 13th Australasian database conference - Volume 5
ICDE '96 Proceedings of the Twelfth International Conference on Data Engineering
A Scalable Algorithm for Answering Queries Using Views
VLDB '00 Proceedings of the 26th International Conference on Very Large Data Bases
Querying Heterogeneous Information Sources Using Source Descriptions
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
Answering queries using views: A survey
The VLDB Journal — The International Journal on Very Large Data Bases
A logic-based approach to data integration
Theory and Practice of Logic Programming
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Query rewriting using views is an important topic in data integration. A number of rewriting algorithms, such as the SVB algorithm, the MiniCon algorithm and the inverse rules algorithm, have been developed. All the algorithms can generate a maximally-contained rewriting of a given query, which is the union of a set of conjunctive rewritings contained in the given query. In this paper, we first argue that the condition for forming a shared-variable bucket in the SVB algorithm can be modified in the case where a shared variable in a query is mapped to a distinguished variable that is also a join attribute in a view. Under the modified condition, we may create more shared-variable buckets so that fewer rewritings can be generated than the SVB algorithm. Second, the SVB algorithm does not handle a constant in a view properly in the case where a shared variable of a query is mapped to a constant of a view. We propose to use a pseudo shared-variable bucket to address this issue. The only difference between the SVB algorithm and the MiniCon algorithm is that the latter considers a head homomorphism on a view. However, the head homomorphism on a view is not related to the condition we intend to modify in this paper. The modifications we present are also applicable to the MiniCon algorithm.