A unifying model of physical databases

Batory, Don; Gotlieb, C. C.

doi:10.1145/319758.319760

Cited by 55 publications

(25 citation statements)

References 25 publications

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“…Shneiderman and Goodman [9] have shown the desirability of batched searches in sequential and tree structure organizations. This paper refines and extends the expressions and results reported by Shneiderman and Goodman [9] and later by Batory and Gotlieb [1]. Shneiderman and Goodman developed expressions to show the savings due to batching in sequential and tree organizations.…”

Section: Introductionsupporting

confidence: 75%

“…As can be seen, with k getting larger, almost the whole file has to be scanned. It should be noted that both papers ( [1] and [9]) have speculated on the form of the above equation, without providing a formal proof. [1] also suggests that the proportion of the file that is accessed is k/(k + 1), and not as in Eq.…”

Section: Sequential Filesmentioning

confidence: 99%

“…It should be noted that the expression due to Shneiderman and Goodman gives savings due to batching, while the expressions due to Batory and Gotlieb are upper-and lower-bound estimates based on somewhat different assumptions. Their assumptions in [1] always require traversing to the highest level in the tree.…”

Section: Sequential Filesmentioning

confidence: 99%

“…Then, the cost of batching can be compared to the cost of any other type of search. (Note that the above authors [1,9] compare the cost of batched k requests to the cost of k individual searches.) The benefits of these expressions threefold: first, the new equations are exact and closed-form (nonrecursive, noniterative) in the sequential case; second, closed-form equations are easier and simpler to use in any further or related work; and, finally, savings due to batching can be obtained in comparison with any other search technique.…”

Section: Introductionmentioning

confidence: 99%

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Expressions for batched searching of sequential and hierarchical files

Palvia

1985

ACM Trans. Database Syst.

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Abstract:Batching yields significant savings in access costs in sequential, tree-structured, and random files. A direct and simple expression is developed for computing the average number of records/pages accessed to satisfy a batched query of a sequential file. The advantages of batching for sequential and random files are discussed. A direct equation is provided for the number of nodes accessed in unbatched queries of hierarchical files. An exact recursive expression is developed for node accesses in batched queries of hierarchical files. In addition to the recursive relationship, good, closed-form upper-and lower-bound approximations are provided for the case of batched queries of hierarchical files. [4,7,8,11]. Different organization structures and access methods are relevant, depending on the usage requirements of the data stored in the files and in the database. In today's proliferation of on-line, fast-response systems, it is very common to have random (hash-based) and indexed file organizations with fast, direct access to individual records in the file. However, in batch applications and some online applications, it may be desirable to sequentially search a batch of records in the file. Shneiderman and Goodman [9] have shown the desirability of batched searches in sequential and tree structure organizations. This paper refines and extends the expressions and results reported by Shneiderman and Goodman [9] and later by Batory and Gotlieb [1]. Shneiderman and Goodman developed expressions to show the savings due to batching in sequential and tree organizations. They did not, however, find exact closed-form expressions. Their expressions were complex recursive relations; they did, however, find a closed-form lower-bound estimate for sequential files. Batory and Gotlieb speculated on the form of the expression for the number of node accesses in a sequential search on the basis of the work in [9].A direct approach is taken here. Rather than obtaining savings due to batching, explicit and accurate expressions are derived for the cost of batching. Then, the cost of batching can be compared to the cost of any other type of search. (Note that the above authors [1,9] compare the cost of batched k requests to the cost of k individual searches.) The benefits of these expressions threefold: first, the new equations are exact and closed-form (nonrecursive, noniterative) in the sequential case; second, closed-form equations are easier and simpler to use in any further or related work; and, finally, savings due to batching can be obtained in comparison with any other search technique.Expressions are developed first for the sequential files and then for hierarchically structured files.

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Section: Introductionsupporting

confidence: 75%

Section: Sequential Filesmentioning

confidence: 99%

Section: Sequential Filesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Expressions for batched searching of sequential and hierarchical files

Palvia

1985

ACM Trans. Database Syst.

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“…The model used here is based on some well-recognized principles of physical design, as reported in many current models [2,3,16,19,23]. These bring out two fundamental principles for physically representing two entities that are related via a relationship.…”

Section: The Generic Physical Design Modelmentioning

confidence: 99%

Sensitivity of the physical database design to changes in underlying factors

Palvia

1988

Information & Management

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Abstract:Several articles have reported on the optimization of the complete physical database design or significant parts of it. However, few results are available on the sensitivity of the physical database design to change in underlying factors that influence the design decisions. Such tenths would be of significant practical value in both the design of the initial physical database and its subsequent restructuring. This paper considers underlying factors related to logical data structure, queries, computer system and physical implementation. An experimental design based on these factors is developed and experiments are conducted to determine the sensitivity effects, and these are reported and discussed. Keywords: Database, Database design, Physical database, Initial database design, Database restructurings, Database monitoring, Sensitivity analysis, Performance evaluation, Optimization, Input-output analysis Article:1. Introduction Sensitivity analysis refers to change in outputs or the final optimal solution due to changes in inputs. It has been applied in many complex settings in different business areas, e.g., in accounting [13], financial management and capital budgeting [12,21], and manufacturing [20). Currently, many computerized tools, such as IFPS [14] and LOTUS [17], facilitate the process of conducting this kind of "what-if" analysis. In addition, operations research has produced formal methods for conducting sensitivity analysis in special cases (e.g., linear programming problems occurring in manufacturing, resource allocation, and scheduling and in inventory management problems [10]). Here we consider the sensitivity of the physical database design to underlying variables. Results were obtained by conducting controlled experiments in a laboratory setting.The design of physical databases is a complex activity. Many researchers have proposed methods to optimize either specific sub-problems in this area [9,11.18,19] or to optimize the entire problem in different contexts [3,6,7,15,16,22,23,24]. They consider many factors simultaneously in the design process. Research/experience does not generally provide information on the sensitivity of the physical database design to the underlying factors. Such results are of significant practical both at initial design and redesign. During the initial design (especially in the absence of optimization tools), the designer is aided in the knowledge of the relative importance of the various factors. This knowledge also helps at redesign time, because the designer is constantly faced with restructuring the physical database due to changing user and technical requirements.What is meant by sensitivity analysis? As the design factors change, both the optimal physical database design itself and the operational cost of using the design may change; indeed the cost will almost always change. However, our main concern in this sensitivity analysis is to study the relative changes in the optimal physical database design. Objectives and Underlying Factors in Physical Database ...

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Sampling algorithms for differential batch retrieval problems (extended abstract)

Willard

1984

Automata, Languages and Programming

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A unifying model of physical databases

Cited by 55 publications

References 25 publications

Expressions for batched searching of sequential and hierarchical files

Expressions for batched searching of sequential and hierarchical files

Sensitivity of the physical database design to changes in underlying factors

Sampling algorithms for differential batch retrieval problems (extended abstract)

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