## Implementation of Nested Relations in a Database Programming Language (1997)

Citations: | 4 - 0 self |

### BibTeX

@TECHREPORT{He97implementationof,

author = {Hongbo He},

title = {Implementation of Nested Relations in a Database Programming Language},

institution = {},

year = {1997}

}

### OpenURL

### Abstract

This thesis discusses the design and implementation of nested relations in Relix, a relational database programming language. The purpose of this thesis is to integrate nested relations into Relix. While a flat relation is defined over a set of atomic attributes, a nested relation is defined over attributes which can include non-atomic ones, i.e. a data item itself can be a relation. To show the power of relational database systems, it is desirable to have nested relations in Relix. Our implementation was done using existing relational functionalities of Relix, without any modification of the physical data representation. Instead of focusing on nesting and unnesting as the major research direction of nested relations, we built nested relations on top of flat relations and we built nested queries by allowing the domain algebra to subsume the relational algebra. Users are able to take advantage of nested relations in Relix with only minimal new syntax being added to the sys...

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Citation Context ... The topic of this thesis focuses on the implementation of nested relations in Relix, a relational database system developed at McGill. The relational model for representing data was proposed by Codd =-=[Cod70]-=- in the early seventies. Since then, it has gained an undisputable key position in the commercial database industry. The nested relational model [Mak77] was developed as an extension of the relational... |

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Citation Context ...d map processing, computer aided design and scientific applications was realized in the late 1970's, thus leading to the introduction of nested relations [Mak77] and the non-first-normal-form (NF 2 ) =-=[Jae82]-=-. CHAPTER 1. INTRODUCTION 6 Project Manager Detail P Name Budget(K) Joe P1 40 P2 30 Sue P2 30 P3 20 P4 30 Figure 1.1: Nesting 1.4.1 Nested Relations The relation Project in Figure 1.1 gives an example... |

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Citation Context ...can be thought of as a collection of methods for building new tables that constitute answers to queries. Codd defined a set of relational operations and proved that they are "relationally complet=-=e" 1 [Cod72]-=-. Relations are considered atomic objects in the relational algebra, and access to tuples within a relation is precluded. Thus the notation and manipulations that must be done are greatly simplified [... |

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Citation Context ...ve been proposed to practical query languages such as SQL to accommodate nesting [Pis86][Kor89]. Implementation of databases based on the nested relation model are also available such as of in [Sps87]=-=[Des88]-=-[Sab89]. These are either built on top of existing relational databases, or from scratch. 1.4.3 Our Approach We view nested relations in a different light. We do not restrict our approach to nesting a... |

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Citation Context ... join is needed in the NF 2 representation. ffl Low level implementation techniques such as clustering and repeating fields can be represented using the formalism defined by the nested relation model =-=[Kor89]-=-. 1.4.2 Nesting and Unnesting In the literature, defining a nested relational model was done by extending relational operators to nested relations, and adding two restructuring operators, NEST and UNN... |

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Citation Context ...ting and Unnesting In the literature, defining a nested relational model was done by extending relational operators to nested relations, and adding two restructuring operators, NEST and UNNEST [Jae82]=-=[Fis85]-=-. The NEST operator creates partitions which are based on the formation of equivalence classes [Kor89]. Tuples are equivalent if the values of the same attributes which are not nested are the same in ... |