Peters, R.J. and Oszu, M.T., Axiomatization of Dynamic Schema Evolution in Object-Bases.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....in chapter 3; the main difference is that in developing the DCM in Prolog a prototype of the system has been also obtained. This mechanism is of particular use in order to specify additional elements of OODBs, like, for example: richer semantic models [Castellanos et al. 1992] schema evolution [Peters zsu, 1995], definition of derived classes [Abiteboul Bonner, 1991; Santos, 1995] definition of external schemas [Rundensteiner, 1992c; Samos, 1995] In order to specify an external schema definition DCM according to [Samos, 1995] a conceptual schema definition DCM, an object definition DCM and the ....

R. Peters, M. zsu, "Axiomatization of Dynamic Schema Evolution in Objectbases," Proc. Int'l IEEE Conf. Data Engineering, pp. 156-164, Tapei, March 1995.

....although there are over 20 members in the ODMG consortium, to the best of our knowledge we are the first to look at providing an extensible ODMGcompliant schema evolution framework. Our OQL SERF tool focuses on an implementation of the SERF framework based on the ODMG standard. Peters and Ozsu [PO95] have introduced a sound and complete axiomatic model that can be used to formalize and compare schema evolution modules of OODBs. This is the first effort in developing a formal basis for schema evolution research, and we utilize their notations for the description of our invariants and ....

....results in a consistent new schema [BKKK87] The consistency of a schema is defined by a set of so called schema invariants of the given object model [Br e96] In this section, we present the invariants for the ODMG object model. We have adapted the axiomatic model proposed by Peters and Ozsu [PO95] in order to axiomatize the schema changes for the ODMG Object Model 9 . 6.1.1 Axiomatization of Schema Changes As described in Section 5.1, a type in an object model defines the properties of the objects. Most object models support the notion of subtyping of these types. Typical valid schema ....

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R. J. Peters and M. T. Ozsu. Axiomatization of Dynamic Schema Evolution in Objectbases. In IEEE International Conference on Data Engineering, pages 156--164, 1995.

....vendors. Today, although there are over 20 members in ODMG consortium, to the best of our knowledge we are the first to look at providing an extensible ODMG compliant schema evolution framework. OQL SERF focuses on an implementation of the SERF framework based on the ODMG standard. Peters and Ozsu [16] have introduced a sound and complete axiomatic model that can be used to formalize and compare schema evolution modules of OODBs. This is the first effort in developing a formal basis for schema evolution research, and we utilize their notations for the description of our invariants and ....

....always results in a consistent new schema [1] The consistency of a schema is defined by a set of so called schema invariants of the given object data model [2] In this section, we present the invariants for the ODMG object model. We have adapted the axiomatic model proposed by Peters and Ozsu [16] in order to axiomatize the schema changes for the ODMG object model. As described in Section 5.1 a type in an object model defines the properties of its associated objects. Most object models support the notion of sub typing of these types. Typical schema changes like adding and dropping of ....

R.J. Peters and M.T. Ozsu. Axiomatization of Dynamic Schema Evolution in Objectbases. In IEEE Int. Conf. on Data Engineering, pages 156--164, 1995.

....rules and schema invariants. Furthermore, we expand the schema change framework with new constructs including new schema change operators, new resolution rules, and new invariants necessary for handling additional features specific to the real time aspects of ROMPP. We use an axiomatic model [32] [32] to formally express the semantics of schema changes. This allows well defined semantics (as opposed to other schema evolution models that are vaguely described in English language) and easy comparison with other yet to be developed real time schema evolution approaches. In this paper, we ....

....and schema invariants. Furthermore, we expand the schema change framework with new constructs including new schema change operators, new resolution rules, and new invariants necessary for handling additional features specific to the real time aspects of ROMPP. We use an axiomatic model [32] [32] to formally express the semantics of schema changes. This allows well defined semantics (as opposed to other schema evolution models that are vaguely described in English language) and easy comparison with other yet to be developed real time schema evolution approaches. In this paper, we also ....

[Article contains additional citation context not shown here]

R.J. Peters, and M.T. Ozsu, "Axiomatization of Dynamic Schema Evolution in Objectbases," Proceedings of the 11th International Conference on Data Engineering, March 1995, pp. 156-164.

....details, including the internal structure of objects. The TIGUKAT model allows dynamic type, class, behavior, and function creation, modification, and 3 TIGUKAT TYPE SYSTEM 4 deletion. The issues related to schema evolution in the TIGUKAT object model are discussed in [P O95a] and [P O95b] Persistence in TIGUKAT is orthogonal (independent of type) OPS 95] There are also some additional considerations about TIGUKAT persistence related to the structure of the model (for example, the type and the class of a persistent object have to be persistent as well) however, these ....

Randal J. Peters and M. Tamer Ozsu, Axiomatization of dynamic schema evolution in objectbases, Proceedings of the 11th International Conference on Data Engineering, March 1995.

....in this area tends to provide the users with a fixed set of schema evolution operations [FFM 95, BKKK87] No provision is made for the situation where this does not meet the user s specific needs. How to add extensibility to schema evolution is now the focus of our effort. Peters and Ozsu [PO95] have introduced a sound and complete axiomatic model that can be used to formalize and compare schema evolution modules of OODBs. This is the first effort in developing a formal basis for schema evolution research, and it may in the future be a foundation based on which to further formalize the ....

R.J. Peters and M.T. Ozsu. Axiomatization of dynamic schema evolution in objectbases. In IEEE Int. Conf. on Data Engineering, pages 156--164, 1995.

....object oriented database systems. In this chapter, various approaches to schema change evolution are reviewed, before the approach followed in this report is described. 4. 1 Varieties of Schema Evolution The different kinds of schema modification can be divided into the following broad categories [PO95] ffl adding and dropping types (classes 1 ) ffl adding and dropping type properties (type redefinition) and ffl adding and dropping sub supertype relationships. Schema evolution refers to changes in the database schema during the existence of the database. Dynamic schema evolution is the ....

....type properties (type redefinition) and ffl adding and dropping sub supertype relationships. Schema evolution refers to changes in the database schema during the existence of the database. Dynamic schema evolution is the management of schema changes while the database system is in operation [PO95] In most cases, schema changes have a large impact on the database system, in particular, when change propagation is necessary. Change propagation refers to the need for propagating schema changes to the objects. This is necessary when 1 The term type is used throughout this report for ....

[Article contains additional citation context not shown here]

R. J. Peters and M. T. Ozsu. Axiomatization of dynamic schema evolution in objectbases. In Proceedings of the 11th International Conference on Data Engineering, pages 156--164, March 1995.

....rules and schema invariants. Furthermore, we expand the schema change framework with new constructs including new schema change operators, new resolution rules, and new invariants necessary for handling additional features specific to the real time aspects of ROMPP. We use an axiomatic model [32] to formally express the semantics of schema changes. This allows well defined semantics (as opposed to other schema evolution models that are vaguely described in English language) and easy comparison with other yet to be developed real time schema evolution approaches. In this paper, we also ....

....conversion. Therefore, we only describe the impact of schema changes on existing data without discussing when and how they are actually converted. D. 1 Axiomatization of Schema Changes To introduce a formal specification of schema change semantics, we adopt an axiomatic model similar to the one in [32], which has been proven sound and complete. The main differences between ours and that in [32] are: ffl We use the terminology of class, subclass and superclass (descendant and ancestor) instead of type, subtype, and supertype. ffl The Axiom of Pointedness is not used, since there is no single ....

[Article contains additional citation context not shown here]

R.J. Peters, and M.T. Ozsu, "Axiomatization of Dynamic Schema Evolution in Objectbases," Proceedings of the 11th International Conference on Data Engineering, March 1995, pp. 156-164.

....conversion. This technique is adopted because ObjectStore allows the addition of leaf types to the database schema without the need to call the schema evolution 2 A discussion of the different schema evolution strategies is out of the scope of this thesis. The reader is referred to [Sch96] and [PO95] for such discussion. facility. These types are added automatically to the database schema whenever an application using these types opens the database. Other applications will not be affected by the database schema unless they need to use the new types; in this case such applications have to ....

R. J. Peters and M. T. Ozsu. Axiomatization of dynamic schema evolution in objectbases. In Proceedings of the 11th International Conference on Data Engineering, pages 156--164, March 1995.

....description of the object model. Abiteboul et al. have in [AHV95] have presented a formal description of a schema. We have used this definition and much of their formalism in our work. We have extended their schema definition to now explicitly include the concept of relationships. Peters and Ozsu [PO95] have introduced a sound axiomatic model to formalize and compare schema evolution modules of OODBs. We utilize their notations with our extensions for the description of our invariants and primitives. 10 Conclusion In this work, we have addressed the issue of evolving relationships. Within ....

R.J. Peters and M.T. Ozsu. Axiomatization of Dynamic Schema Evolution in Objectbases. In IEEE Int. Conf. on Data Engineering, pages 156--164, 1995.

....in this area tends to provide the users with a fixed set of schema evolution operations [FFM 95, BKKK87] No provision is made for the situation where this does not meet the user s specific needs. How to add extensibility to schema evolution is now the focus of our effort. Peters and Ozsu [PO95] have introduced a sound and complete axiomatic model that can be used to formalize and compare schema evolution modules of OODBs. This is the first effort in developing a formal basis for schema evolution research, and it may in the future be a foundation based on which to further formalize the ....

Randall J. Peters and M. Tamer Ozsu. Axiomatization of dynamic schema evolution in objectbases. In IEEE International Conference on Data Engineering, pages 156--164, 1995.

....object oriented database systems. In this chapter, various approaches to schema change evolution are reviewed, before the approach followed in this thesis is described. 4. 1 Varieties of Schema Evolution The different kinds of schema modification can be divided into the following broad categories [PO95] ffl adding and dropping of classes, ffl adding and dropping class properties (class redefinition) and ffl adding and dropping sub superclass relationships. Schema evolution refers to changes in the database schema during the existence of the database. Dynamic schema evolution is the management ....

....class properties (class redefinition) and ffl adding and dropping sub superclass relationships. Schema evolution refers to changes in the database schema during the existence of the database. Dynamic schema evolution is the management of schema changes while the database system is in operation [PO95] In most cases, schema changes have a large impact on the database system, in particular, when change propagation is necessary. Change propagation refers to the need of propagating schema changes to the objects. This is necessary when the database schema is changed in a way that existing class ....

R. J. Peters and M. T. Ozsu. Axiomatization of dynamic schema evolution in objectbases. In Proceedings of the 11th International Conference on Data Engineering, March 1995.

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Peters, R.J. and Oszu, M.T., Axiomatization of Dynamic Schema Evolution in Object-Bases.

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P O95. Randal J. Peters and M. Tamer Ozsu. Axiomatization of dynamic Schema Evolution in Objectbases. In Proc. of the 11th Int'l Conf. on Data Engineering (ICDE), Taipei, Taiwan, March 1995. IEEE Press.

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