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Advantages and disadvantages, architectures and data models

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Presentation on theme: "Advantages and disadvantages, architectures and data models"— Presentation transcript:

1 Advantages and disadvantages, architectures and data models
Lecture 3

2 Advantages redundancies can be reduced inconsistencies can be avoided
sometime redundant data is necessary inconsistencies can be avoided data can be shared data independence improved maintenance of the IS

3 Advantages integrity can be maintained security can be imposed
concurrent access can be achieved better recovery mechanism IS’s conflicting requirements can be balanced

4 Disadvantages complexity higher impact of failure
seem to require more work (skills, time, resources …) eventually it pays off higher impact of failure possibly, reduced local performance

5 The client-server architecture

6 (Totally) Distributed database systems

7 Data models recall: physical data independence
how is data described and manipulated at the conceptual/logical level? concepts operators grammatical rules (these apply to any formal language)

8 A theoretical model (theory) - Lego

9 Data models the relational model the entity relationship (E/R) model
E/R diagram the enhanced E/R model (EE/R) the object oriented model the object/relational model the logic model

10 Data modelling and database development

11 Course syllabus - main topics
generalities the relational model SQL database design / modelling data protection advanced topics / new trends

12 Activity Have you ever used a theoretical model? Have you ever done Maths? Have you ever programmed? How is music described? Can you see any similarities between these disciplines? Can you infer a model for data modelling based on a theoretical model you know and the requirements for data modelling?

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