P.-A. Larson and H. Z. Yang. Computing queries from derived relations: Theoretical foundations. Technical Report CS-87-35, Department of Computer Science, University of Waterloo, 1987.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....and not on scalable deployments over the Web. Related to the problem of update filtering is query containment the problem of deciding whether a query is contained in the union of a set of views or cached queries. A wealth of previous work exists in the area of query containment and equivalence [17, 14, 5]. Previous work in the area of materialized view routing (i.e. answering queries by rewriting using materialized views) also describes techniques for matching and containment. Most related to our work is the event matching approach of publish subscribe systems [1] Gryphon uses a parallel search ....

P.-A. Larson and H. Z. Yang. Computing queries from derived relations: Theoretical foundations. Technical Report CS-87-35, Department of Computer Science, University of Waterloo, 1987.

....(A; B) and S = B; C) and one view V = R . S, and consider the query Q = oe A=a R. Clearly, Q cannot be answered from the view V , because the join would not necessarily include all of R s tuples. This translation problem (for conjunctive queries and views) has been addressed by Larson and Yang [10, 11], by Levy et al. 12] and by Brodsky and Motro [5] We shall assume that a translation algorithm exists which is sound and complete; i.e. it computes all the correct translations that exist. 7 Assume a multidatabase with scheme D and mapped views M . The answer to a query Q on this ....

P.-A. Larson and H. Z. Yang. Computing queries from derived relations: Theoretical foundations. Technical Report CS-87-35, Department of Computer Science, University of Waterloo, August 1987.

....on a given set of views of these relations has been encountered in at least three applications. In this section we describe these applications and we comment on the solutions that have been designed. 2. 1 Physical Database Design The first to have addressed this problem have been Larson and Yang [4, 5]. The context in which the problem was discussed is physical database design for relational databases. The standard approach to physical database design is to maintain a one to one correspondence between the relations declared in the scheme of the database and the relations that are actually ....

P.-A. Larson and H. Z. Yang. Computing queries from derived relations: Theoretical foundations. Technical Report CS-87-35, Department of Computer Science, University of Waterloo, August 1987.

....B) and S = B; C) and one view V = R . S, and consider the query Q = select A=a R. Clearly, Q cannot be answered from the view V , because the join would not necessarily include all of R s tuples. This translation problem (for conjunctive queries and views) has been addressed by Larson and Yang [24, 25], by Levy et al. 26] and by Brodsky and Motro [9] We shall assume 14 that a translation algorithm exists which is sound and complete; i.e. it computes all the correct translations that exist. 3.8 Multidatabase Constraints Recall that a multidatabase query is simply a query Q of the scheme D. ....

P.-A. Larson and H. Z. Yang. Computing queries from derived relations: Theoretical foundations. Technical Report CS-87-35, Department of Computer Science, University of Waterloo, August 1987.

....predicates is actually updated or inserted. A similar scheme called precision locks was proposed in [Bannerjee 1981] for centralized systems. Query containment [Sagiv 1980] is a topic closely related to the cache completeness question. Query evaluation on a set of derived relations is examined in [Larson 1987]. Independence of datalog queries from updates is investigated in [Levy 1993] Efficient maintenance of materialized views has also been the subject of much research [Blakeley 1986, Ceri 1991, Gupta 1993] and is very related to the issues examined in this paper. For example, our update ....

P.A. Larson and H.Z. Yang, "Computing Queries from Derived Relations: Theoretical Foundation," Research report CS-87-35, University of Waterloo, August 1987.

....are related to the issues of view and query optimization. Cached data can be seen as materialized views on which index structures can be built to retrieve the tuples of the base relations. The concept of view has been widely used for many purposes and techniques developed in view maintenance [7, 8, 18, 20] are of interest for several areas such as integrity constraint maintenance, query processing, active database, and cache refresh operations. In this paper we consider two problems. The first one is how to efficiently cache nested tuples defined as the result of materialized views over a ....

P.A. Larson, H.Z. Yang. Computing Queries from Derived Relations: Theoretical Foundation. Research Report CS-87-35, University of Waterloo, August 1987.

....notified by the server of the conflict) only when a tuple in the intersection of shared predicates already exists or is actually updated or inserted. Query containment [18] is a topic closely related to the cache completeness question. Query evaluation on a set of derived relations is examined in [15]. Efficient maintenance of materialized views has also been the subject of much research [2, 6, 10, 14] and is related to the issues examined in this paper. For example, our update notification scheme involves detecting whether an update has an effect on a client cache, and this has much in ....

P.A. Larson and H.Z. Yang, "Computing Queries from Derived Relations: Theoretical Foundation, " Research report CS-87-35, University of Waterloo, August 1987.

....to be meaningful ; transaction consistency on the other hand may be selected by the client transaction according to its requirements for isolation, and be enforced by the caching system. Among other related work, algorithms for query containment [20] and query evaluation using materialized views [16] are adopted for our SQL Cache containment reasoning process. Efficient maintenance of materialized views has been the focus of much research [12] and is related to the cache currency issues examined in this paper. Client side data caching has been investigated in several recent studies [7, 22, ....

P.-A. Larson and H.Z. Yang, "Computing Queries from Derived Relations: Theoretical Foundation," Research report CS-87-35, Computer Science Department, University of Waterloo, 1987.

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P.-A. Larson and H. Z. Yang. Computing queries from derived relations: Theoretical foundations. Technical Report CS-87-35, Department of Computer Science, University of Waterloo, 1987.

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Larson, P. A. and Yang, H. Z. (1987) Computing Queries from Derived Relations: Theoretical Foundation. Technical Report CS-87-35, Department of Computer Science, University of Waterloo, Ontario.

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P.-A. Larson and H. Z. Yang. Computing queries from derived relations: Theoretical foundations. Technical Report CS-87-35, Department of Computer Science, University of Waterloo, 1987.

No context found.

P.-A. Larson and H. Z. Yang. Computing queries from derived relations: Theoretical foundations. Technical Report CS-87-35, Department of Computer Science, University of Waterloo, 1987.

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