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Databases : Object-Oriented DB. 2007, Fall Pusan National University Ki-Joune Li. Object-Oriented DB. Weak Points of Relational DB Lack of Expressive Power Non 1NF Impedance Mismatch Mismatches between DB and Host Languages Demands for complicated DB in late 1980s

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Databases : Object-Oriented DB

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Databases object oriented db

Databases : Object-Oriented DB

2007, Fall

Pusan National University

Ki-Joune Li


Object oriented db

Object-Oriented DB

  • Weak Points of Relational DB

    • Lack of Expressive Power

    • Non 1NF

    • Impedance Mismatch

      • Mismatches between DB and Host Languages

  • Demands for complicated DB in late 1980s

    • CAD, GIS, VLSI DB, Multimedia

      • Need more expressive power

    • Relational Data Model

      • Good since it is simple

      • Bad since it lacks of expressive power


Relational model lack of expressive power

Relational Model: Lack of Expressive Power

  • Example

    • Description of Road Network by Relational Data Model

  • How to compute the shortest path from two points

    • Navigation by Point number: extremely expensive

    • Why this problem? : Lack of Expressive Power


Relational model 1nf

Relational Model: 1NF

  • 1NF: Only Atomic Value in a field

    • Example

Neither very natural,Nor efficient


Relational model 1nf1

Relational Model: 1NF

  • Non-1NF: Any Type for a field

    • Set, List, Table

    • NO MORE Relational Algebra

      • No Selection, No Join etc..

    • User-Defined Type

    • Example

OK


Relational model impedance mismatch

Relational Model: Impedance Mismatch

  • Separation between Data and Program

    • Data: Relational Algebra: Declarative Approach

    • Program: Procedural Language like Java and C

       Totally different approaches

  • Impedance Mismatch

    • Difficult to develop

Program

Mismatch

DB


Persistent object

Persistent Object

  • Objects in OOPL like Java, Smalltalk, and C++

    • Persistency:

      • The states of objects remain after the termination of program

      • OOPL: Not persistent

    • If Persistent  DB and OO DB

  • Persistent Object

    • NO MORE Impedance Mismatch

    • Functions for DB in language itself

  • OOPL + DB

    • Persistent Type

    • Example

      • Persistent Smalltalk

      • Persistent C++

      • Persistent Java


Stored procedure in oodb

Stored Procedure in OODB

  • Example: Polygon

    • Data

    • Methods (Operations)

      • Intersect,

      • Contain,

      • Etc..

Persistent Object

Program

Program

Stored Procedure

Data

DB

Polygon

Data

Intersect

Contain

Etc..


Some important aspects of oodb

Some Important Aspects of OODB

  • Object Identifier

  • User-Defined Type

  • Version Control


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