S.B. Zdonik: "Data Abstraction and Query Optimization", pp. 368--373 in [17].  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... Work The mainbody of work in object oriented query processing focuses on structural aspects and is thus closely related to work on relational query processing (e.g. 29] A large number of query languages and object oriented algebras where proposed in this direction [13] 31] 33] 35] 37] 39] 41][45]. Closely related to this are works on different variants of indexing techniques for path expressions [7] 8] 30] This work has already developed into a stable framework for query languages on the structural part of object oriented databases, for overviews see [9] 27] In [43] an architecture ....

S.B. Zdonik: "Data Abstraction and Query Optimization", pp. 368--373 in [17].

....also been developed [BK86] Osborn [Osb88, Osb89] describes an object algebra which views objects as passive data and does not support encapsulation. Her algebra allows aggregate or set objects to be disassembled and recombined and then reused in later stages of a query. Zdonik and Shaw [SZ89, Zdo88] developed an object algebra which supports encapsulation but only allows unary methods to be used in qualifying algebra operators. They also introduce an id equal at depth i comparison operator which allows structural comparisons of objects. Results of queries are always new objects. Thus the ....

....Consider the case where the result of one query is used as the input to another. How can we insure that methods referenced in the predicate of the second query are defined on all objects in the result of the first Previous algebras have imposed type restrictions such as union compatibility [SZ90, Zdo88] on the algebra operators to insure the type consistency of the result. Union compatibility states that members of the sets being operated on must be instances of types which are in a subtype relationship with one another. The type of the result is considered to be the most general supertype of ....

S. B. Zdonik. Data Abstraction and Query Optimization. In K. R. Dittrich, editor, Advances in Object-Oriented Database Systems, volume 334 of Lecture Notes in Computer Science, pages 368--373. Springer Verlag, 1988.

....we consider a structurally object oriented data model, we do not have the problem of optimizating queries including methods. Other algebraic formalisms for structurally object oriented data models have been suggested in several projects ( Osborn 1988] Straube 1991] Vandenberg and DeWitt 1991] [Zdonik 1988]) 5.6 Conclusion In this paper, we first have presented the structurally object oriented data model NO 2 , including the data definition facilities, a descriptive query language, and an algebraic formalization. As far as algebraic optimization is concerned, rules and equivalences known from ....

S.B. Zdonik. Data Abstraction and Query Optimization. In K.R. Dittrich (Ed.): Advances in Object-Oriented Database Systems, Lecture Notes in Computer Science 334, Springer 1988.

....Since in closed algebras the result of one query is used as the input to another, there is a need to insure that methods referenced in the predicate of the second query are defined on all objects in the result of the first. Some algebras impose type restrictions such as union compatibility [SZ90, Zdo88] on the algebra operators to insure the type consistency of the result. Union compatibility states that members of the sets being operated on must be instances of types which are in a subtype relationship with one another. The type of the result is considered to be the most general supertype of ....

S. B. Zdonik. Data abstraction and query optimization. In K. R. Dittrich, editor, Advances in Object-Oriented Database Systems, volume 334 of Lecture Notes in Computer Science, pages 368--373. Springer Verlag, 1988.

.... navigation and queries (as opposed to conventional database systems (e.g. Stonebraker, 1990] that support only queries) Furthermore, it supports full indexing for queries over sets of abstract objects, as opposed to the more limited techniques in [Bertino, 1989, Maier, 1986, Stonebraker, 1990, Zdonik, 1988]. Concurrency control and recovery are provided for individual objects (unlike many other systems such as [Atkinson, 1983, Haskin, 1987] furthermore programmers can control the granularity of concurrency control and recovery (the techniques in [Weihl, 1985] are being extended here) Unlike all ....

Zdonik S. (1988) Data Abstraction and Query Optimization. In Proceedings of the Second International Workshop on Object-Oriented Database Systems, pages 368--373.

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