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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

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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