Gail M. Shaw and Stanley B. Zdonik. An Object-Oriented Query Algebra. In Richard Hull, Ron Morrison, and David Stemple, editors, Second International Workshop on Database Programming Languages, Oregon, USA, pages 103--112. Morgan Kaufman, June 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... idea of representing constraints as equivalences between boolean valued (OQL actually) queries already appears in [FRV96] The equational theory of CoDi proves almost the entire variety of proposed algebraic query equivalences beginning with the standard relational algebraic ones, and including [SZ89a,SZ89b], CD92,Clu91,FM95b,FM95a] and the very comprehensive work by Beeri and Kornatzky [BK93] Moreover, using especially (commute) CoDi validates and generalizes standard join reordering techniques, thus the problem of join associativity in object algebras raised in [CD92] does not arise. Our PC ....

G. Shaw and S. Zdonik. An object-oriented query algebra. In Proc. DBPL, Salishan Lodge, Oregon, June 1989.

.... a comprehensive study of the algorithms presented in [Flo96] The chase backchase technique and the monad algebra laws given in [LT97, PT99, PT98] prove almost the entire variety of proposed algebraic query equivalences beginning with the standard relational algebraic ones, and including [SZ89a, SZ89b] CD92, Clu91, FM95b, FM95a] and the very comprehensive work by Beeri and Kornatzky [BK93] Our PC queries are less general than COQL queries [LS97] by not allowing alternations of conditionals and BigU. However we are more general in other ways, by incorporating dictionaries and considering ....

G. Shaw and S. Zdonik. An object-oriented query algebra. In Proc. DBPL, Salishan Lodge, Oregon, June 1989.

.... optimization is quite comprehensive as it is possible to represent almost the entire variety of equivalences stated in various papers, beginning with the standard relational algebraic optimizations, continuing with OODB optimizations as in the work of Cluet, Zdonik, Maier, Fegaras and others [42, 43, 19, 18], and in fact including the very comprehensive work by Beeri and Kornatzky [8] Use of referential integrity constraints to eliminate dependent joins is implicit in Orion optimizations [26] and the type based approach of [19] This, and the use of precomputed ASR s appear in [28, 29] Precomputed ....

G. Shaw and S. Zdonik. An object-oriented query algebra. In Proc. DBPL, Salishan Lodge, Oregon, June 1989.

....our techniques to the maintenance of materialized views. Implementation and conclusions are in Section 11. 2 Related Work Query optimization Our approach to query optimization based on algebraic rewriting rules is inspired on relational [20] and object oriented query optimization (e.g. [37], 16] This is not surprising, since it has been noted in the context of object oriented databases that relational query optimization can be well extended to complex structures ( 33] 24] However, the differences between the problem we treat here and conventional query optimization, which we ....

G. M. Shaw and S. B. Zdonik. An object-oriented query algebra. In Second Intern. Workshop on Database Programming Languages (DBPL'89), pages 103--112, 1989.

....search strategies have been developed in the relational context. Much effort has been done in order to adapt the techniques developed for the relational database systems to the object oriented environment. For instance, a number of researchers have worked on algebraic query rewriting (e.g. [17, 6, 18], others have extended relational search strategy [16] However, the characteristics of the object oriented environment had lead to consider entirely new techniques. First, objects are not flat tuples. An object may recursively refer to other objects. In this context, queries often involve ....

....rewriting techniques, ii) that allows easy and exhaustive factorization of duplicated subqueries, and (iii) that supports heuristics in order to reduce the optimization rewriting phase. There exist two main approaches to query rewriting in the object oriented context: the algebraic approach [17, 6, 18] and the one, that we call the type based approach, which transform pointer chasing into join operations [13, 15] We unify these two appoaches in one formalism. We show that it is just the lack of type information (membership to class extents) that makes it impossible to perform type based ....

[Article contains additional citation context not shown here]

G. Shaw and S. Zdonik. An Object-Oriented Query Algebra. In Proc. DBPL, Salishan Lodge, Oregon, USA, June 1989.

....the satisfiability problem for uniquetyped conjunctive queries is solvable in polynomial time. Most work on query optimization for an OODB implicitly assumes either a query language for complex objects with object identifiers or the type of an attribute is unique in the inheritance 5 hierarchy [17, 32, 33, 34, 7, 20, 27, 12]. Our work 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 ....

Shaw, G.M. and Zdonik, S.B., "An Object-Oriented Query Algebra," Proceedings of the 2th International Workshop on Database Programming Languages , (Hull, R., Morrison, R. and Stemple, D., Eds.), Morgan Kaufmann Publishers Inc., San Mateo, Cal., 1990, pp. 103-112.

....system, because there are a number of different ways to express a join in such systems. In this thesis, we ignore the optimization of joins written in a non procedural fashion. They can be optimized using standard relational techniques [SELI79] or the more complex techniques developed for OODBSs [SHAW89, BEER90, VAND91]. Instead, we will concentrate on set iterators. Since DBPLs such as PASCAL R [SCHM77] O 2 [LECL89] E [RICH92] and O [AGRA89] provide constructs to iterate through a set in some unspecified order, it is possible to nest iterators to express value based joins. The following is an example of a ....

Gail Shaw and Stanley Zdonik. An Object-Oriented Query Algebra. Data Engineering 12,3 (September 1989), 29-36.

.... two forms of collections unary and binary to represent entity categories and relationships, respectively, means that our algebra differs from other algebras in its provision of operations specific to binary collections (relationships) Andersen [And91] Scholl et al. [SST92] Shaw and Zdonik [SZ89] SZ90] and Straube [Str90] all restrict their attention to set collections. Both Cluet et al. [CDLR90] and Vandenberg and DeWitt [VD91] cater for multiple kinds of collections. Arising from the two forms of collections unary and binary the collection algebra has two groups of operations. ....

G. M. Shaw and S. B. Zdonik. An Object-Oriented Query Algebra. In Proceedings of the 2nd Workshop on Database Programming Languages. Morgan Kaufmann, June 1989. 10

....our techniques to the maintenance of materialized views. Implementation and conclusions are in Section 9. 2 Related Work Query optimization Our approach to query optimization based on algebraic rewriting rules is inspired on relational [14] and object oriented query optimization (e.g. [28], 12] This is not surprising, since it has been noted in the context of object oriented databases that relational query optimization can be well extended to complex structures ( 24] 17] However, the differences between the problem we treat here and conventional query optimization, which we ....

G. M. Shaw and S. B. Zdonik. An object-oriented query algebra. In Second Intern. Workshop on Database Programming Languages (DBPL'89), pages 103--112, 1989.

....the equivalences inv 1 5 is analogous. The approach of [Clu92] retains a separation of DML and programming language; thus, the possibility of non termination or infinite data structures are not considered. Several other groups have introduced object algebras and strategies for their optimisation [Dem94, Lie92, Sha89, Sto91, Van91] with analogous equivalences to those we propose here. In general these algebras are either computationally incomplete or support optimisations for only a subset of their operators. Also, some provide only limited facilities for optimising user defined data types; while others allow few algebraic ....

Shaw, G.B. and Zdonik, S.B. An object oriented query algebra, Proc. 2nd DBPL, Morgan-Kaufman, 1989.

....the intensional and extensional effects of using abstraction mechanisms in data modeling and using constructs in the query language in querying the database. The recognition of the importance of precisely defining these effects, especially for object oriented query languages, is relatively recent [Beec88, Kim89a, Shaw89, Banc90]. Finally, the capabilities of the DBPL are demon strated by its application to the problem of simulation support [Mill89, Mill90, Pott90, Mill91b, Mill91c, Koch91a] 2. The Active KDL Schema Definition Language A schema is used to specify the object types available to database users. ....

Shaw, G.M., and B. Zdonik, "An Object-Oriented Query Algebra,", Proceedings of the Second International Workshop on Database Programming Languages, R. Hull, R. Morrison, and D. Stemple (Eds.), Gleneden Beach, OR (June 1989).

.... of object equality is the same as identity equal defined in [KC86] or 0equality defined in [LRV88] We do not define, at this level, any notions of shallow or deep equality found in other models [KC86, LRV88, Osb88] or extended versions of these which determine equality at various levels [SZ89, SZ90] These notions can be defined as identity equivalence relationships on the behavioral characteristics of objects and therefore should be left to customized interpretations at the behavioral level rather than being part of the primitive model definition. For example, the model may provide ....

....by the complete lattice shown in Figure 3.2. By definition, any object of type T must support the behaviors of all types in 3 T . In other words, any behaviors which operate on objects of a type T oe 2 3 T must operate on objects of type T . Some have called this substitutability [SZ89] because an object of type T can be used (substituted) in any context specifying a supertype of T . We refine the definition of conformance from [Str91] to describe this property. We first define a conforms to relation on the type T object as follows: Behavior 3.8 Conforms to (B conformsTo ....

G. Shaw and S. Zdonik. An Object-Oriented Query Algebra. In Proc. 2nd Int'l Workshop on Database Programming Languages, pages 103--112, Gleneden Beach, Oregon, June 1989.

....have 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 ....

....as aggregations, not ADTs, and no discussion is presented on how to process and optimize such queries. This thesis focuses on formal query languages by developing both an object calculus and an object algebra. Our query languages differ from those of Osborn [Osb88] Alashqur [ASL89] and Shaw [SZ89] in that we support strict encapsulation, i.e. operators which manipulate or depend on the object representation are not allowed. Chapter 8 addresses how the addition of new operators affects the overall query processing methodology. 1.4 Organization of this Thesis This thesis is divided into ....

[Article contains additional citation context not shown here]

G. Shaw and S. Zdonik. An Object-Oriented Query Algebra. Quart. bull. of the IEEE TC on Data Engineering, 12(3):29--36, September 1989.

....Dayal. The EQUAL query algebra and related results in query equality and equivalence were developed under the supervision of Zdonik. My optimization results were developed in collaboration with Zdonik and Dayal. The presentation in this dissertation is based in part on the published papers [105, 108, 132, 133, 134] 1 , an invited report [154] and Brown University reports [104, 107] The publications [132, 133, 134, 154] report on my work with Zdonik; the others on my work with Dayal and Zdonik. Mitchell (Shaw) is the primary author on all papers with the exception of [154] which describes primarily the ....

....supervision of Zdonik. My optimization results were developed in collaboration with Zdonik and Dayal. The presentation in this dissertation is based in part on the published papers [105, 108, 132, 133, 134] 1 , an invited report [154] and Brown University reports [104, 107] The publications [132, 133, 134, 154] report on my work with Zdonik; the others on my work with Dayal and Zdonik. Mitchell (Shaw) is the primary author on all papers with the exception of [154] which describes primarily the work of Zdonik. The papers map to the dissertation as described in the following annotated bibliography: 133] ....

[Article contains additional citation context not shown here]

Gail M. Shaw and Stanley B. Zdonik. An Object-Oriented Query Algebra. In Proceedings of the 2nd International Workshop on Database Programming Languages, pages 103--112, June 1989. Reprinted in IEEE Data Engineering Bulletin,12,3, September 1989.

....developed. In this area, the most progress has been made in the specification of SQL and rule based languages [5, 9, 28, 39, 47] Although proposals for function based object algebras have appeared in the literature, such algebras strongly resemble the algebras defined for complex object databases [13, 18, 46, 53]. Defining algebras in this fashion deviates from the basic philosophy of the pure function based approach as the level of abstraction at which these algebras operate is several layers higher than the graphoriented nature of the function based approach. Given this situation, we propose a simple ....

G. Shaw and S. Zdonik. An Object-Oriented Query Algebra. In Data Engineering, September 1989, pp. 12(3):29-- 36.

....to be a direct subtype of itself. By definition, any object of type T must support the behaviors of all types in the superlattice T . In other words, any behaviors that operate on objects of a type T oe 2 3 T must operate on objects of type T . Some have called this substitutability [SZ89] because an object of type T can be used (substituted) in any context specifying a supertype of T . The definition of conformance is refined from [Str91a] to describe this property, but first a conforms to relation on the type T object is defined as follows: Behavior 2.6 Conforms to (B ....

....plus the join term. A similar approach is described by the OOAlgebra of OODAPLEX [Day89] A variant of these approaches is defined by the TIGUKAT algebra because the uniform functional approach fits in naturally with the behavioral nature of the query model. The object algebra of Shaw and Zdonik [SZ89, SZ90] is based on a set and tuple model and consistently extends the relational algebra with both object preserving and objectcreating operators. Their algebraic operators work on collections of objects that have parameterized set types. The algebra defines traditional set operations, along with ....

G. Shaw and S. Zdonik. An Object-Oriented Query Algebra. In Proc. of the 2nd Int'l Workshop on Database Programming Languages, pages 103--112, June 1989.

....that plant communities whose plants all have the same type exhibit certain temperature patterns. The user could then create a derived subclass of Plant community, Homogeneous community (also shown in Figure 1) to keep closer track of those communities and the experiments that use them. Encore [SZ89] supports derived subclasses whose rule is a predicate. 3 The Data Definition Language of Moose A Moose schema is composed of classes and relationships between classes. The data definition language provides statements to create and destroy both classes and relationships, and to relabel existing ....

.... are several other declarative query languages that have been proposed for OO data models, namely O2query [BCD89] Extra Excess [CDV88] CQL [DGJ92] COQL [NO92] OQL [ASL89] IQL [AK89] XSQL [KKS92] Ontos s OSQL [Ont92] and the Orion query language [Kim89] as well as the Equal query algebra [SZ89] Fox differs from them in several aspects. The two most prominent ones are its ability to use complex path expressions to navigate any path in the schema graph in any direction, even through inheritance relationships, and its ability to associatively retrieve individual elements of an ....

[Article contains additional citation context not shown here]

G. M. Shaw and S. B. Zdonik. An Object-Oriented Query Algebra. In R. Hull, R. Morrison, and D. Stemple, editors, Proceedings of the International Workshop on Database Programming Languages, pages 103--112, San Mateo, CA, 1989. Morgan-Kaufman, Inc.

....as objects having an invoke (or apply) function defined at their interface. 3.6 Object Algebra The definition of FROOM includes an object algebra that resembles an extended relational algebra. The concepts used are based largely on those in PDM algebra [MANO86] OOAlgebra [DAYA89] and EQUAL [SHAW89], but also include concepts from object logics, e.g. MAIE86, KIFE89] The algebra is not intended for use by either programmers or end users, but as a notation for defining the basic functions to be built into implementations of the object model, and for defining the semantics of expressions in ....

G. M. Shaw and S. B. Zdonik, "An Object-Oriented Query Algebra", in

....plus the join term. A nearly identical approach is described by the OOAlgebra of OODAPLEX [Day89] We define a variant of these approaches in our algebra since their uniform functional approach fit in naturally with the behavioral nature of our query model. The object algebra of Shaw and Zdonik [SZ89, SZ90] is a set and tuple model that consistently extends the relational algebra with both object preserving and object creating operators. The algebraic operators work on collections of objects which have parameterized set types. The algebra defines traditional set operations along with a ....

G. Shaw and S. Zdonik. An Object-Oriented Query Algebra. In Proc. 2nd Int'l Workshop on Database Programming Languages, pages 103--112, June 1989.

....objects and insisting that the results of such queries should be values. The drawback of this approach is that a structure transforming query does not preserve properties of objects including sharing relations and object identity. In some languages, so called objectcreating queries are allowed [AK89, Day89, SZ89, Kim89, Cat94]; the result of an object creating query is new objects independent of any existing ones. Of course, creation of new objects is sometimes necessary, but this mechanism can not be a substitute for the ability to transform the structures of existing objects while preserving their identity. In order ....

Gail M. Shaw and Stanley B. Zdonik. An object-oriented query algebra. In Proc. Int. Workshop on DBPL, pages 103--112, Jun. 1989.

....of complex queries in any rewriting system. Indeed, as in any rewriting system, the problem consists in rewriting the query in order to obtain a join involving several subqueries on distinct elements. In the OO context, algebraic equivalences for performing this rewriting can be found in [SZ89b, SZ89a, SZ89c, S Ozsu90] Of course, this is not always feasible and, in some cases, we will have to construct more data than needed (in the worst case, the whole data corresponding to a view will have to be loaded) 5 Optimizing the grammar In the previous section, we assumed that the grammar is not ....

G. Shaw and S. Zdonik. An Object-Oriented Query Algebra. In Proc. DBPL, Salishan Lodge, Oregon, June 1989.

....discussion of the problems raised above. In Section 4 we discuss some of the current approaches to solving these problems and in Section 5 we conclude with a brief summary. 2 An Object Oriented Data Model and Algebra We use the ENCORE data model and query algebra (EQUAL; Encore QUery ALgebra) SZ89b, SZ90] as the foundation for our discussion of problems in object oriented query processing. The model incorporates data modelling features found in other object oriented systems, such as abstract data types, subtyping (inheritance) encapsulation, complex structures, object identity, and ....

Gail M. Shaw and Stanley B. Zdonik. An Object-Oriented Query Algebra. In Proceedings of the 2nd International Workshop on Database Programming Languages, pages 103--112, June 1989. Reprinted in IEEE Data Engineering Bulletin,12,3, September 1989.

....the notion of equivalence of object oriented queries is defined. We discuss query optimization in section 4 and present a variety of transformations satisfying our different definitions of equivalence. 2. THE ENCORE QUERY ALGEBRA Our query algebra is based on the ENCORE object oriented data model [8, 9, 10]. The model includes abstract data types, type inheritance, typed collections of typed objects, and objects with identity. We query over collections of objects using the type of objects in the collection as a scheme for the collection. The collections are considered to be homogeneous, although the ....

Shaw, G. M. and Zdonik, S. B., "An Object-Oriented Query Algebra," in Proceedings of the 2nd International Workshop on Database Programming Languages, June 1989. Reprinted in IEEE Database Engineering, September 1989.

No context found.

Gail M. Shaw and Stanley B. Zdonik. An Object-Oriented Query Algebra. In Richard Hull, Ron Morrison, and David Stemple, editors, Second International Workshop on Database Programming Languages, Oregon, USA, pages 103--112. Morgan Kaufman, June 1989.

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Shaw, G.B. and Zdonik, S.B. An object oriented query algebra, Proc. 2nd DBPL, Oregon, June 1989, pp 103-112.

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