W. S. Cho, C. M. Park, K. Y Whang, and S. H. So. A new method for estimating the number of objects satisfying an object-oriented query involving partial participation of classes. Information Systems, 21(3):253--267, 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....technique which facilitates construction of class hierarchies for efficient query processing. Keywords : Object oriented database, horizontal class partitioning, cost model, query processing, predicate selectivity, hill climbing heuristic. 1 Introduction Object oriented database systems (OODBSs) [1, 4, 6] are emerging as the next generation database technology especially for new applications, e.g. CAM CAD, Software Engineering and multimedia databases. Horizontal partitioning is a technique for reducing the disk accesses to execute a query by minimizing the number of irrelevant objects accessed ....

....access an attribute A n , or a method m n of this class which returns a value or set of OIDs. The length of the path P is defined by the number of attributes, n, in P . We call the first class C 1 the starting class and the last attribute (or method) A n the ending attribute or method of the path [6]. Definition 4 (Component predicate) A component predicate p j (1 j N) is a predicate defined on a path. A query that involves component predicate(s) will be called a component query. Example 2 A component query which retrieves the names of all employees which work on Database project is ....

W. S. Cho, C. M. Park, K. Y Whang, and S. H. So. A new method for estimating the number of objects satisfying an object-oriented query involving partial participation of classes. Information Systems, 21(3):253--267, 1996.

....an attribute A n , or a method m n of this class which returns a set of values or set of OIDs. The length of the path P is defined by the number of attributes, n, in P . We call the first class C 1 the starting class and the last attribute (or method) A n the ending attribute or method of the path [8]. We consider a typical object query language which is of form: SELECT result list FROM target class WHERE qualification clause The result list involves only attributes or methods from a single class. The quantification clause defines a boolean combination of predicates by using the ....

W. S. Cho, C. M. Park, K. Y Whang, and S. H. So. A new method for estimating the number of objects satisfying an object-oriented query involving partial participation of classes. Information Systems, 21(3):253--267, 1996.

.... query processing in object oriented database systems is an important issue for enhancing the performance of objectoriented database systems [14, 18] Although most object oriented database systems provide high level query languages[11, 13, 18] query optimization techniques are immature yet [3, 6, 7, 14, 18]. Most of the previous query optimization techniques in objectoriented database systems use a variant of Proceedings of the Fifth International Conference on Database Systems for Advanced Applications, Melbourne, Australia, April 1 4, 1997. relational query optimization techniques for the ....

W. S. Cho, C. M. Park, K. Y. Whang, and S. H. Son. A new method for estimating the number of objects satisfying an object-oriented query involving partial participation of classes. Information Systems, Volume 21, Number 3, pages 253--267, 1996.

....by Kifer et al. 11] An important feature of Kifer s query model is the extended path expression: a A pred1 B Idx2 Idx1 pred4 Idx3 pred5 pred2 E C D p1 p2 p3 p4 p5 p6 p9 p7 p8 pred3 Figure 2. A Query Graph. path expression that includes domain or codomain substitutions represented by selector[7, 11]. For example, the path expression Student.own[Truck] color includes the domain codomain substitution for the attribute own; i.e. the domain of the attribute own is substituted by (or limited to) the class Trcuk, and the codomain to the class Student. Predicates that can be processed by using ....

....are uniformly distributed in the class C i ; i = 1; 2; n. Note that this assumption does not modify the commonly accepted definition of uniform distribution[16, 17] but extends the definition according to the subclasses in the class inheritance hierarchy and domain substitutions(selectors[11] [7]. In [7] we fully discuss this assumption. 2) The distribution of different attribute values are not correlated, i.e. attribute independence, 3) An OID consists of a class id, instance id pair, where class id is the identifier of the class to which the object belongs, and instance id is the ....

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W. S. Cho, C. M. Park, K. Y. Whang, and S. H. Son. A new method for estimating the number of objects satisfying an object-oriented query involving partial participation of classes. Information Systems, 21(3):253--268, 1996.

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