Transforming Conceptual Models to ObjectOriented Database Designs

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Transforming Conceptual Models to Object-Oriented
Database Designs

• Practicalities, Properties, and Peculiarities

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Extending Past Successes

• Past ad-hoc and empirical techniques and
  theoretical research
• Provide a formal foundation to build on these
  past successes

3
Process

• Begin with a conceptual model
• Characterize a restricted set of instances
• Develop an algorithm
• Make accommodations
• FLEXIBILITY IS KEY
• PROCESS IS ABOUT REDUCTION

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Begin With A Conceptual Model

• OSA (Object-oriented Systems Analysis)
• Object Sets (Rectangles)
• Lexical (Dashed)
• Non-lexical (Solid) gtgt OIDs
• Relationship Sets (Diamonds)
• Constraints
• Generalized functional dependencies
• Participation constraints
• 1 gtgt exactly one
• 1 gtgt one or more
• 0 gtgt zero or more

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Sample OSA Diagram
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OSA ? Design Hypergraph
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Process Overview

• Phase 1 Functional Dependency Analysis
• Phase 2 Reduction Transformations
• Lexicalization ltEmp (of Employee)gt
• Object Sets for Roles

Item Nr (of Item on Order)
SPECIALIZATION
GENERALIZATION
Item Nr (of Item)
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Process Overview

• Discard Redundant Edges and Edge Counterparts
  Using Various Algorithms
• In doing this we now have a Reduced Design
  Hypergraph
• Phase 3 Restricted Reduced Design (RRD)
  Hypergraph
• Phase 4 Produce Nested Normal Forms (NNF)
  schemes from RRD Hypergraphs

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Adjustments for Generated Schemes

• Chosen Roots
• What are the best roots for the nested relation
  scheme?
• Flexibility in Edge Configurations
• Use 2 Heuristics
• Large Objects
• No Updates
• Computed Objects

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Paper Retrospective

• Good presentation of challenges faced in
  migrating/designing OODBs
• Inconclusive after presenting concrete algorithms
• What ifs at end make you second guess the
  usefulness of the presented algorithm
• Good introduction to future research