Borgida, A. "Type Systems for Querying Class Hierarchies with Non Strict Inheritance," Proceedings of the 8th ACM Symposium on Principles of Database Systems , Philadelphia, Pennsylvania, 1989, pp. 394-401.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....assumes an inheritance hierarchy in which type of an attribute need not be unqiue and hence our query model is more realistic than most previous work. We study the satisfiability problem by using typing contraints imposed by the inheritance hierarchy and the condition specified in a query. Borgida [8] addressed a similar problem. However he is only interested in the type checking of a query. Moreover, the kind of inheritance hierarchy and queries assumed are also different from ours. To our best knowledge, this represents the first work on query satisfiability in an object oriented setting. ....

Borgida, A. "Type Systems for Querying Class Hierarchies with Non Strict Inheritance," Proceedings of the 8th ACM Symposium on Principles of Database Systems , Philadelphia, Pennsylvania, 1989, pp. 394-401.

....write exception handling code. Bor88] addresses the problem of inapplicable attributes and return exceptions due to attribute domain redefinition. The notion of excuses serves to distinguish between desired exceptions and errors. A type system that supports these excuses is formally defined in [Bor89] along with an efficient algorithm to statically detect unsafe statements. Check clauses are provided by the user. He she formulates the correction condition in an extensional way, testing the run time type of expressions. The type system verifies that the correction condition implies the safety ....

A. Borgida. Type systems for querying class hierarchies with non-strict inheritance. In Proceedings of the eight ACM Symposium on Principles of Database Systems, Philadelphia, PA, March 1989.

....(e.g. 27, 15, 26, 21, 22] These query languages, like those of the relational model, transfer the burden of choosing an efficient execution plan for a query to the database system. This has lead to a resurrection of the study of query optimization in the object oriented setting (e.g. [30, 8, 7, 31, 18, 23, 13]) Most of these papers develop transformations that reduce the cost of evaluating a given query but do not necessarily produce an optimal equivalent query. In the setting of relational databases, a well accepted notion of query optimality exists for the class of conjunctive queries [12] and the ....

....queries in [18] Our results are complementary, in that the language in [18] is object generating, while our language is object preserving . Our language enables a user to retrieve objects from a database, but not to create new complex objects. Moreover, our language, like the one in [8], is defined on an inheritance hierarchy, whereas most languages studied in the literature are languages for complex objects without inheritance. The need to deal with inheritance introduces an extra level of complexity into the containment and optimization problems. In an OODB, classes are named ....

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Borgida, A. "Type Systems for Querying Class Hierarchies with Non Strict Inheritance," Proceedings of the 8th ACM Symposium on Principles of Database Systems, Philadelphia, Pennsylvania, 1989, pp. 394-401.

....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 other recent work in this direction see [8, 18]. We propose method schemas as a simple abstraction of the object oriented programs that are being used in most of the existing database prototypes. The critical features of method schemas are classes with methods and inheritance, a syntax involving method composition, recursion and name ....

A. Borgida. Type Systems for Querying Class Hierarchies with Non-strict Inheritance, Proc. ACM PODS, 394--400, 1989.

....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 other recent work in this direction see [8, 18, 22]. We propose method schemas as a simple abstraction of the object oriented programs that are being used in most of the existing database prototypes. The critical features of method schemas are classes with methods and inheritance, a syntax involving method composition, recursion and name ....

A. Borgida. Type Systems for Querying Class Hierarchies with Non-strict Inheritance, Proc. ACM PODS, 394--400, 1989.

.... Thus, various extensions to the paradigm have been considered, some of which explore the concept of class virtualization [TYI88, AB91, SLT91] the associated idea of defining multiple interfaces to an object [SS89, TYH 91, RS91] the definition of non strict inheritance mechanisms [Bor88, Bor89] or alternatives to class inheritance for sharing and extending properties [Lie86, TYH 91] That amounts to a revision of the object oriented paradigm which is driven by database and software engineering as well as knowledge representation (AI) concerns. In this spirit, many proposals have ....

....base, represents a context switch and provides a means for dealing with the dynamics of database applications which is not favored by conventional object oriented models. There are yet several issues not yet fully resolved such as the placement of virtual classes in the hierarchy [Run92, Bor88, Bor89, Lie86, RS91] optimized strategies for solving resolution conflicts, or the lazy evaluation of virtual and imaginary extensions. Furthermore, it is necessary to explore how the view mechanism can be used in several contexts. To conclude, we briefly mention some. from schema company schema ....

Alexander Borgida. Type Systems for Querying Class Hierarchies with Non-strict Inheritance. Technical report, Rutgers University, New Brunswick (NJ US), 1989.

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