SQL schema design: foundations, normal forms, and normalization

Köhler, Henning; Link, Sebastian

doi:10.1016/j.is.2018.04.001

Cited by 37 publications

(23 citation statements)

References 25 publications

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“…Hence, another extension of our work to handling null marker occurrences is desirable. Recently, schema normalization in the presence of null markers has been considered as well [34,35]. Just like schema designs for certain data depend on the identification of semantically meaningful FDs, schema designs for uncertain data depend on the identification of semantically meaningful pFDs.…”

Section: Future Workmentioning

confidence: 99%

Relational database schema design for uncertain data

Link

Prade

2019

Information Systems

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a b s t r a c tDriven by the dominance of the relational model, we investigate how the requirements of applications on the certainty of functional dependencies can improve the outcomes of relational database schema design. For that purpose, we assume that tuples are assigned a degree of possibility with which they occur in a relation, and that functional dependencies are assigned a dual degree of certainty which says to which tuples they apply. A design theory is developed for functional dependencies with degrees of certainty, including efficient axiomatic and algorithmic characterizations of their implication problem. Naturally, the possibility degrees of tuples bring forward different degrees of data redundancy, caused by functional dependencies with the dual degree of certainty. Variants of the classical syntactic Boyce-Codd and Third Normal Forms are established. They are justified semantically in terms of eliminating data redundancy and update anomalies of given degrees, and minimizing data redundancy of given degrees across all dependency-preserving decompositions, respectively. As a practical outcome of our results, designers can simply fix the degree of certainty they target, and then apply classical decomposition and synthesis to the set of functional dependencies whose associated degree of certainty meets the target. Hence, by fixing the certainty degree a designer controls which integrity requirements will be enforced for the application and which data will be processed by the application. The choice of the certainty degree also balances the classical trade-off between query and update efficiency on future database instances. Our experiments confirm the effectiveness of our control parameter, and provide original insight into classical normalization strategies and their implementations.

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Section: Future Workmentioning

confidence: 99%

Relational database schema design for uncertain data

Link

Prade

2019

Information Systems

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“…There has been a plethora of research on finding suitable extensions for the notion of an FD to accommodate missing data. This has led to useful notions such as weak and strong FDs [24,25], no information FDs [4,16], or possible and certain FDs [19,21]. However, all of these notions assume that the same interpretation applies to all occurrences of the null marker in the given data set, such as "value does not exist", "value exists but is unknown", or "no information".…”

Section: Desideratamentioning

confidence: 99%

“…Secondly, schema design for data with missing values has been a long-standing open problem [15,19,25]. Almost exclusively, the main focus of the research has been on suitable extensions of FDs to incorporate null markers.…”

Section: Related Workmentioning

confidence: 99%

“…A second limitation is that the complexity of reasoning becomes often prohibitively expensive to guarantee efficient schema designs [25]. Recently, the concept of possible and certain FDs was introduced and shown to provide suitable extensions of schema design for data with missing values, at least in terms of BCNF [19,21]. The work contains a review and comparison of FD extensions to data with missing values.…”

Section: Related Workmentioning

confidence: 99%

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Embedded functional dependencies and data-completeness tailored database design

Wei

Link

2019

Proc. VLDB Endow.

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We establish a robust schema design framework for data with missing values. The framework is based on the new notion of an embedded functional dependency, which is independent of the interpretation of missing values, able to express completeness and integrity requirements on application data, and capable of capturing many redundant data value occurrences. We establish axiomatic and algorithmic foundations for reasoning about embedded functional dependencies. These foundations allow us to establish generalizations of Boyce-Codd and Third normal forms that do not permit any redundancy in any future application data, or minimize their redundancy across dependency-preserving decompositions, respectively. We show how to transform any given schema into application schemata that meet given completeness and integrity requirements and the conditions of the generalized normal forms. Data over those application schemata are therefore fit for purpose by design. Extensive experiments with benchmark schemata and data illustrate our framework, and the effectiveness and efficiency of our algorithms, but also provide quantified insight into database schema design trade-offs.

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“…The aim of the research was to ascertain the communal farmers' perceptions and experiences regarding the current communal market system. Most studies such as: [1][2][3][4][5][6][7] have shown that lack of access to markets, minimal access to financial assistance, high transaction costs, poor infrastructure, such as roads and market, and lack of comprehensive information about existing individual farmer, farmer organisations or unions profile, and lack of access to appropriate information, technology and extension services, makes communal market system unattractive and limit farmers` participation [10]. Many communal and smallholder farmers face a range of barriers that limit their ability to participate in markets.…”

Section: Introductionmentioning

confidence: 99%

Perceptions and Experiences Regarding the Current Market System by Communal Farmers in Mhondoro-Mubaira (Zimbabwe)

Muchesa¹

2018

IJSDR

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The objective of this research was to ascertain the communal farmers' perceptions and experiences regarding the current communal market system. The study was carried out in the area of Mhondoro-Mubaira, situated in Mashonaland West province of Zimbabwe. The population samples for the study comprised of communal farmers (N=150) and extension officers (N=25. According to the study, private buyers are the most preferred buyers for all the produce, for field, garden crops and livestock. The reason for favorable rating of the private buyers is they offer competitive prices, they pay the farmers on delivery of produce and sometimes they cover transport costs. Even though the private buyers are the most preferred buyers, farmers still prefer selling produce between themselves and the open market because they have control of the prices especially for livestock. The Grain Marketing Board and the Cold Storage Commission, which are government run, are the least favorable markets for the farmers. This is because these institutions offer the lowest prices, they do not pay on delivery and offer any assistance to the farmers regarding transport/transport costs. The results show that the farmers are not satisfied with the of the current market system which they deem restrictive, minimally supported by the government, low participation by the private sector, and the current economic situation in Zimbabwe overburdens the situation. The government of Zimbabwe needs to create a conducive environment for private players to participate with government interferences through overburdening policies.

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SQL schema design: foundations, normal forms, and normalization

Cited by 37 publications

References 25 publications

Relational database schema design for uncertain data

Relational database schema design for uncertain data

Embedded functional dependencies and data-completeness tailored database design

Perceptions and Experiences Regarding the Current Market System by Communal Farmers in Mhondoro-Mubaira (Zimbabwe)

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