S. Abiteboul, P.C. Fischer, and H.J. (Eds.) Schek. Nested Relations and Complex Objects in Databases. Springer Verlag, 1987.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... distribution [4, 11] Even the recent attempts to generalize the standard Bayesian database model, including horizontal independencies [7, 43] complex values [21, 43] and distributed Bayesian networks [8, 42, 46] parallel the development of horizontal dependencies [12] complex values [1, 19], and distributed databases [9] in the relational database model. More importantly, the implication problem for both models coincide with respect to two important classes of independencies, the BMVD class [14] used in the construction of Markov networks) and the conflict free sets [31] used in ....

S. Abiteboul, P. Fischer, and H. Schek. Nested Relations and Complex Objects in Databases, volume 361. Springer-Verlag, 1989.

.... distribution [4] 10] Even the recent attempts to generalize the standard Bayesian database model, including horizontal independencies [6] 44] complex values [20] 44] and distributed Bayesian networks [7] 43] 47] parallel the development of horizontal dependencies [11] complex values [1], 18] and distributed databases [8] in the relational database model. More importantly, the implication problem for both models coincide with respect to two important classes of independencies, the BMVD class [13] used in the construction of Markov networks) and the conflict free sets [31] ....

S. Abiteboul, P. Fischer, and H. Schek, Nested Relations and Complex Objects in Databases. New York: Springer-Verlag, 1989, vol. 361.

....a unique object in the database which can reference other hypernodes. Traditionally flat databases, as in the relational model, have been su#cient to model most applications, but recently, it has been proposed to extend the modelling power of flat databases to nested (or complex object) databases [AFS89] which allow the nesting (or encapsulation) of entities, and to object oriented databases [Kim90] which, in addition, allow cyclic references between objects. For the purpose of this paper we concentrate on the data modelling aspects of objects and ignore the wider issues of object orientation in ....

S. Abiteboul, P.C. Fischer, and H.-J. Schek, editors. Nested Relations and Complex Objects in Databases, volume 361 of Lecture Notes in Computer Science. Springer-Verlag, Berlin, 1989.

....and iteration facilities. KEY WORDS: nested relations, null values, null extended algebra, faithful extended algebra operators, precise extended algebra operators ############### Appeared in Fundamenta Informaticae, Vol. 19, pp. 303 343, 1993. 2 1. Introduction The nested relational model [1, 2, 8, 13, 15, 16, 19, 20, 21, 22, 23, 26, 28] was developed in order to extend the applicability of the relational model [5, 18, 27] to more complex, nonbusiness applications such as CAD, image processing and text retrieval [2] Nested relations can model complex data directly by recursively defining values of attribute domains to be either ....

....pp. 303 343, 1993. 2 1. Introduction The nested relational model [1, 2, 8, 13, 15, 16, 19, 20, 21, 22, 23, 26, 28] was developed in order to extend the applicability of the relational model [5, 18, 27] to more complex, nonbusiness applications such as CAD, image processing and text retrieval [2]. Nested relations can model complex data directly by recursively defining values of attribute domains to be either flat relations in first normal form [5, 18, 27] or nested relations. Recently many extended algebras have been suggested for the nested relational model [1, 3, 6, 8, 10, 15, 16, 17, ....

S. Abiteboul, P.C. Fischer and H.-J. Schek (Eds.), Nested Relations and Complex Objects in Databases. Lecture Notes in Computer Science, vol. 361. Springer-Verlag, Berlin, 1989.

....of a tuple must be atomic, i.e. undecomposable as far as the relational model is concerned. The 1NF requirement yields flat tabular representations of relations. The relations that are in 1NF are also called flat relations. 1 CHAPTER 1. INTRODUCTION 2 The nested relational model [Mak77, SS87, AFS89] was developed in order to extend the flat relational model to applications in which attribute values may have complex structure. The nested relational model removes the restriction of 1NF from the flat relational model, and allows attribute values to be relation valued as well as atomic. The ....

....model, which extends the flat relational model in order to allow the representation of hierarchically structured data. Research into the nested relational model began in the late 1970 s [Mak77] and in recent years a lot of effort has been expended in order to further develop this model [SS87, AFS89] In section 2.3, we describe the approach used in our implementation to support relational algebra and domain algebra for relations with arbitrary level of nesting. 2.1 The Flat Relational Model The relational model of data was introduced by Codd [Cod70, Cod79] It is based on a simple and ....

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S. Abiteboul, P. C. Fischer, and H. J. Schek. Nested Relations and Complex Objects in Databases. Lecture Notes in Computer Science 361. Springer-Verlag, Berlin, 1989.

....WWW: www.luc.ac.be vdbuss . 1 basic data values. These relations can be manipulated using five basic operators which together form the relational algebra. The nested relational model, designed in order to be able to represent complex data structures in a more natural and direct way [10, 3], is a typed higher order extension of the classical flat relational model. In a nested relation, a tuple may consist not only of basic values but also of relations in turn. By canonically generalizing the operators of the relational algebra to work on nested relations, and adding the two ....

S. Abiteboul, P.C. Fischer, and H.-J. Schek, editors. Nested Relations and Complex Objects in Databases, volume 361 of Lecture Notes in Computer Science. Springer-Verlag, 1989.

.... 1 Introduction During the past decades, the nested relational and complex object models [1, 5, 11, 12, 15, 18, 21, 22] were developed to extend the applicability of the traditional relational model to more complex, non business applications such as CAD, image processing and text retrieval [2]. Another important direction of intense research has been in using a logic programming based language Datalog [8, 23] as a database query language. Such a language provides a simple and natural way to express queries on a relational database and is more expressive than the traditional relational ....

S. Abiteboul, P.C. Fisher, and H.J. Schek, editors. Nested Relations and Complex Objects in Databases. Lecture Notes in Computer Science, vol 361, Springer-Verlag, 1989.

.... still relational, approach is the one based on the introduction of relation valued attributes (thus relaxing the first normal form constraint) Makinouchi 77] A new theoretical corpus has been developed for these so called NF 2 (Non First Normal Form) models and implementations are available [Abiteboul 89] With respect to complex object management, the NF 2 approach shows as major restriction the fact that the structure is purely hierarchical : no cycles are allowed (a component cannot be of the same type as the composed object) sharing of components is not always supported. Also, the NF 2 ....

S. ABITEBOUL, P.C. FISCHER, H.-J. SCHEK (Eds.): Nested Relations and Complex Objects in Databases, Lecture Notes in Computer Science #361, Springer-Verlag, 1989

.... (X(T 1 , T i , T n ) 5. Distribute Undistribute a set constructor over a union of types one: T 1 , T 2 , T n ) T 1 ) T 2 ) T n ) 5 These operators are strictly equivalent to unnesting and nesting relations in the NF 2 relational data model [1]. 8 6. Flatten UnAEatten a nested union of types: T 1 , T 1 i , T k i ) T n ) T 1 , T 1 i , T k i , T n ) 7. Invariant structures, i.e. structures that cannot be rewritten into other ones: ffl ( T) T) ffl [ T 1 , ....

S. Abiteboul, P.C. Fischer, and H.J. Schek Eds. Nested Relations and Complex Objects in Databases, volume 361 of Lecture Notes in Computer Science. Springer-verlag, 1989.

.... 1990b ] Let us repeat that choosing how to implement functions (retrieval methods) for an object oriented database schema is essentially the same problem as physical database design for network (CODASYL) databases, or for Complex Object databases (in the sense of [ Abiteboul and Beeri, 1988; Abiteboul et al. 1989 ] or even for relational databases (where the structure stems from key foreign key relationships) 16 Chapter 1. Physical DB Design for an OODBMS 1.3.3 Implementing Types, Classes, and Inheritance Some new aspects in physical database design, however, originate from data modelling ....

S. Abiteboul, P. C. Fischer, and H.-J. Schek, editors. Nested Relations and Complex Objects in Databases. LNCS 361, Springer Verlag, Heidelberg, 1989.

....becomes more pressing. Various implementation oriented modelling techniques exist. A classical distinction can be made between relational, network and hierarchical models. Recently a lot of research has been done on nested relational models, also called non first normal form or NF 2 models (see [1], 6] and [19] These models are interesting for special database applications, involving e.g. textual data, computer aided design or image processing. Current approaches to the transformation of conceptual models into internal models focus mainly on the relational model. The result of the ....

S. Abiteboul, P.C. Fischer, and H.J. (Eds.) Schek. Nested Relations and Complex Objects in Databases. Springer Verlag, 1987.

....used when conveying vague information. Because of this wide spectrum of the need for handling complex and fuzzy information existing in the real world, there have been various researches in the last decade attempting to deal with complex objects in the frame of database systems (NF 2 DB models [2, 41, 48, 17]) OODB Models [22, 51] in knowledge based systems [3] and in coupled systems [33] As separate research attempts, there have also been advances dealing with fuzzy information in database systems [9, 23, 33, 54, 52] and in knowledgebased systems [31, 58] and with other uncertain information in ....

....representations of information may provide a more intuitive user view of data. 3. Non first normal form reduces the number of tuples and eliminates redundancy. 4. Related to the stated three reasons, querying is also simplified [41] The nested relational data model (Non first normal form) [2, 24, 35, 41, 46, 47, 48, 18, 28] was developed in order to extend the support for the complex objects in the relational data model. Nested relations can naturally represent the hierarchy of complex objects by allowing recursively defined relation valued attributes in addition to atomic attributes. We will give a more formal ....

S. Abiteboul, P.C. Fischer, and H.J. Schek, editors. Nested Relations and Complex Objects in Databases, volume 361. Springer-Verlag, Berlin, 1989.

....1995. 1 Introduction In the past decade, the nested relational and complex value models [2, 14, 17, 21, 25, 26, 6] were developed to extend the applicability of the traditional relational model [13, 28] to more complex, non business applications such as CAD, image processing and text retrieval [3]. Extended relational algebra and calculus are provided for such kind of models. It has been proved that extended relational algebra without the powerset operator and safe calculus without the subset predicate are equivalent [26] Queries expressed in either framework can be evaluated in ....

S. Abiteboul, P.C. Fisher, and H.J. Schek, editors. Nested Relations and Complex Objects in Databases. Lecture Notes in Computer Science, vol 361, Springer-Verlag, 1989.

....of the kind set(tuple(a 1 :d 1 , a n :d n ) in which d j denote atomic data sorts. ffl The nested form (NF) models [Mak77, SS86] allow for sort expressions s i with alternating set and tuple constructors so that nested tables can be represented. ffl The complex object (CO) model [AB88, AFS89] does not impose any restriction on the structure of s i . 2.3 Generic functions Sort expressions are usually associated with a large number of generic (or overloaded) functions. There are operations and predicates that ffl compose structured values from simpler ones. For instance, is used ....

S. Abiteboul, P.C. Fischer, and H.J. Schek (eds.), Nested Relations and Complex Objects in Databases, Springer, Berlin, LNCS 361, 1989.

....= tuple(Nodes:set(int) Edges:set(tuple(Start:int, End:int) and union address = union(PA:privateAddress, BA:BusinessAddress) for alternative domains. These constructors can be applied repeatedly to construct domains of any complexity, for example even a so called complex object model database (Abiteboul et al. 1989). Generic sorts are associated with a number of predefined operations and predicates called aggregate functions. For example, CNT counts the elements in a set (list, bag) IN denotes the membership predicate, and PRJi denotes projection on tuple values. For details and further examples see ....

: S. Abiteboul, P.C. Fischer, and H.J. Schek, editors. Nested Relations and Complex Objects in Databases. Springer LNCS 361, 1989.

....lead to the definition of two new data models: the complex value model and the objectbased model. There were also proposals to combine the two approaches [AK89, Bee90, HK87, LRV88] The complex value model (also known as the complex object, nested relational, 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 ....

S. Abiteboul, P. Fischer, and H.-J. Schek, editors. Nested Relations and Complex Objects in Databases, volume 361 of Lecture Notes in Computer Science. Springer-Verlag, 1989.

....[10] have been introduced to deal with data applications involving objects with a complex external and or internal structure. These database models can be classified into three main categories: the complex object models, the function based object models, and hybrids of these. Complex object models [1, 2, 32, 35] (also called value based models) extend the relational model by allowing, besides flat relations, complex object types obtained as a sequence of type constructions, such as tuple, finite) set, finite) list, array, and pointer formation. On the other hand, function based object models [14, 21, ....

....functions (relationships) between objects. In the area of query languages for complex object databases, researchers have successfully extended the well known relational query languages. This has resulted in calculus, algebraic, rulebased, and SQL like query languages for complex object databases [1, 2, 3, 31, 35, 53]. In contrast, the study of query languages for function based object databases is less 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 ....

S. Abiteboul, P. Fischer, and H.J. Schek, editors. Nested Relations and Complex Objects in Databases. # 361 in Lecture Notes in Computer Science, Springer-Verlag, 1989.

....1. Having noted the limitations in the expressive power of traditional relational databases, but also appreciated their popularity and widespread use, attempts have been made to extend the relational model to include OO features. This has led to concepts such as the nested relational database ([1], 9] now called the object relational database. This approach extends the semantics of the original relational model. Early attempts involved models where the value of an attribute could be an entire relation, but the latest third generation object relational databases contain user defined ....

S. Abiteboul, P.C. Fischer, and H.-J. Schek, editors. Nested Relations and Complex Objects in Databases. Springer-Verlag, 1989.

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S. Abiteboul, P.C. Fischer, and H.J. (Eds.) Schek. Nested Relations and Complex Objects in Databases. Springer Verlag, 1987.

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S. Abiteboul, P.C. Fischer, and H.J. (Eds.) Schek. Nested Relations and Complex Objects in Databases. Springer Verlag, 1987.

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S. Abiteboul, P. Fischer, and H. Schek. Nested Relations and Complex Objects in Databases, volume 361. Springer-Verlag, 1989.

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S. Abiteboul, P.C. Fischer, and H.-J. Schek, editors. Nested Relations and Complex Objects in Databases, volume 361 of Lecture Notes in Computer Science. Springer-Verlag, 1989.

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S. Abiteboul, P.C. Fischer, H.-J. Schek (eds.): Nested relations and Complex Objects in Databases. Springer Verlag, 1989. Lecture Notes in Computer Science No. 361.

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S. Abiteboul, P. C. Fischer, and H.-J. Schek, editors. Nested Relations and Complex Objects in Databases. LNCS 361, Springer Verlag, Heidelberg, 1989.

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S. Abiteboul, P.C. Fischer, and H.-J. Schek, editors. Nested Relations and Complex Objects in Databases, volume 361 of Lecture Notes in Computer Science. Springer, Berlin, 1989.

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