R. Hull and J. Su. On accessing object-oriented databases: Expressive power, complexity, and restrictions. In Clifford et al. [8], pages 147--158.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....systems, objects have not only data attributes but also procedural attributes, called methods. Just like the view dictionary discussed in Section 3.1, it would be interesting if these methods can be stored in the database itself. If the methods are implemented using the relational algebra (e.g. [10]) we can again store them in program relations. The reflective algebra can now be used to model applications that require the construction of derived method implementations from existing ones. For example, consider an OODB application where different persons can have different implementations of ....

R. Hull and J. Su. On accessing object-oriented databases: Expressive power, complexity, and restrictions. In Clifford et al. [8], pages 147--158.

....this difficulty, there are three well known approaches: naive approach, limited approach, and expert approach. In a naive approach, all constraints are defined in one place (e.g. a root node or the metaclass ) and all constraints are considered for enforcement. The second approach, used in [5, 6, 7, 8, 10], allows constraints to be defined and associated with an object. Only those constraints (so called intraobject constraints) associated with an object or inherited from a supertype object are considered when an update or a query is presented to the object. However, no propagation of update ....

....object types (or classes) Since constraints are scattered in an object oriented database, inference is limited either to within an object type to which the constraints are associated or outside the scope of individual object types by means of explicit triggers. Propagation algorithms (e.g. in [8]) are executed in a predesignated manner for all users to make use of the same database constraints. In these algorithms, constraints are activated by explicitly predefined activators. Although Hull and Su [8] have developed objectoriented constraint languages, the concept of method is ignored. ....

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Richard Hull and Jianwen Su. On accessing object-oriented databases: expressive power, complexity, and restrictions. In Proc. ACM SIGMOD Intl. Conf. on Management of Data, pages 147--158, Portland, Oregon, 1989.

....moves beyond NF 2 models and systems, the implementation status and examples will largely be omitted. We will not discuss the relative power of the underlying data models, exhaustive sets of algebraic equivalence rules, or other theoretical language issues. Many of these issues are covered in [Pare88, VanG87, VanG86, Hull87, Hull89a, Chan88]. The purpose of this survey is to convey some idea of the general nature of database algebras in 9 the hope of gaining some insight into why certain operations exist and of identifying common themes among these algebras. It is inevitable that some algebras have been either omitted or described ....

R. Hull and J. Su, "On Accessing Object-Oriented Databases: Expressive Power, Complexity, and Restrictions ", Proc. ACM SIGMOD Conf., Portland, Oregon, 1989.

....NF 2 , or unnormalized model [AFS89] is an extension of the standard relational model [Ull88] While the relational model offers collections of tuples, the complex value model offers collections of arbitrary combinations of sets and tuples called complex values. In the object based model [GPVG94, HS89, HY90, KV93, KW93], a database is thought of as a labeled graph of objects, where each set of equally labeled objects comprises a so called class. The edges between objects in the graph express properties and are labeled by property names. This approach is inspired by the objectoriented philosophy [KL89] but can ....

....be constructed so that (by Theorem 5.7) abstraction can be expressed. Consequently, languages providing the possibility to perform an action on each element of a set in some nondeterministic order can express abstraction. Examples are the language TL [AV90] and some of the languages considered in [HS89]. 6.3 Duplicate elimination versus copy elimination In this paper, we have concentrated on complex value queries, as defined in Section 3. However, as we observed in Section 2, programs in OBQL (and OBQL abstr for that matter) in general have the effect of augmenting a database with derived ....

R. Hull and J. Su. On accessing object-oriented databases: Expressive power, complexity, and restrictions. In Clifford et al.

....y Dipartimento di Informatica e Sistemistica, Universit a di Roma La Sapienza , Via Salaria 113, I 00198 Roma, Italy. Email: cabibbo dis.uniroma1.it. Partially supported by MURST and CNR. z Dept. Math. Computer Sci. University of Antwerp (UIA) Universiteitsplein 1, B 2610 Antwerpen, Belgium. E mail: pareda uia.ac.be x INRIA (Projet VERSO) Domaine de Voluceau, Rocquencourt, B.P. 105, F 78153 Le Chesnay Cedex, France. E mail: vdbuss uia.ac.be. On leave from the University of Antwerp. Research Assistant of the Belgian National Fund for Scientific Research. ....

....113, I 00198 Roma, Italy. Email: cabibbo dis.uniroma1.it. Partially supported by MURST and CNR. z Dept. Math. Computer Sci. University of Antwerp (UIA) Universiteitsplein 1, B 2610 Antwerpen, Belgium. E mail: pareda uia.ac.be x INRIA (Projet VERSO) Domaine de Voluceau, Rocquencourt, B.P. 105, F 78153 Le Chesnay Cedex, France. E mail: vdbuss uia.ac.be. On leave from the University of Antwerp. Research Assistant of the Belgian National Fund for Scientific Research. properties of the receiving object, but may also have side effects. Hence, at the most general level, we can define an ....

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R. Hull and J. Su. On accessing object-oriented databases: Expressive power, complexity, and restrictions. In J. Clifford, B. Lindsay, and D. Maier, editors, Proceedings of the 1989 ACM SIGMOD International Conference on the Management of Data, volume 18:2 of SIGMOD Record, pages 147-- 158. ACM Press, 1989.

....N00014 83 K 0146 ARPA Order No. 6320 1, and an Alfred P. Sloan Fellowship. x Dept. of Computer Science, Brown University. sr cs.brown.edu. Work supported by ONR Contract N0001491 J 4052, ARPA Order 8225. principles of these new systems have also been investigated. For example, 1] and [17] address the expressibility of languages in this new context, and use many of the tools of typed complex structure and semantic modeling research. Here, we do not examine such structural aspects, but focus instead on some of the behavioral aspects of the object oriented paradigm for some ....

R. Hull, J. Su. On Accessing Object-Oriented Databases: Expressive Power, Complexity, and Restrictions. Proc. ACM SIGMOD, 147--158, 1989.

....[2, 5, 10, 17] The complex value model 1 [1] is an extension of the standard relational model. While the relational model offers collections of tuples, the complex value model offers collections of arbitrary combinations of sets and tuples called complex values. In the object based model [8, 11, 13, 16, 15], a database is essentially thought of as a labeled graph of objects, where each set of equally labeled objects comprises a so called class. The edges between objects in the graph express properties and are labeled by property names. This approach is inspired by the object oriented philosophy ....

R. Hull and J. Su. On accessing object-oriented databases: Expressive power, complexity, and restrictions. In Clifford et al. [7], pages 147--158.

....of base values (i.e. relations) However, since tuples and sets may be represented by an object identifier OID [19] our model only needs flat structures, i.e. there are no tuples of tuples, tuples of sets, or sets of sets. The expressive power is still the same as if we permit such structures [14]. The base values together with the sets of base values comprise the base part of our model, tuples and relations form the relational part, and the object part which provides for handling of tuple and set structured objects completes the fundamentals of the model (see Figure 1) Together, ....

R. Hull and J. Su. On accessing object-oriented databases: Expressive power, complexity, and restrictions. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 147--158, 1989.

....N00014 83 K 0146 ARPA Order No. 6320 1, and an Alfred P. Sloan Fellowship. x Dept. of Computer Science, Brown University. sr cs.brown.edu. Work supported by ONR Contract N0001491 J 4052, ARPA Order 8225. principles of these new systems have also been investigated. For example, 1] and [17] address the expressibility of languages in this new context, and use many of the tools of typed complex structure and semantic modeling research. Here, we do not examine such structural aspects, but focus instead on some of the behavioral aspects of the object oriented paradigm for some ....

R. Hull, J. Su. On Accessing Object-Oriented Databases: Expressive Power, Complexity, and Restrictions. Proc. ACM SIGMOD, 147--158, 1989.

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R. Hull, J. Su, On Accessing Object-Oriented Databases: Expressive Power, Complexity, and Restrictions, Proc. ACM SIGMOD Int. Conf. on Management of Data, 1989

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