Theme Of Presentation

Theme of Presentation The presentation is about “5” Different Database Architectures Or Database Models. By

Junaid Ali Siddiqui

Need of different designs: • The use of database Management system to store data. – We know: – Database? – Collection of logically related data, design to meet the needs of information in an organization.

– Relationship b/w different files? – Defined by the logical and physical design. – It implies the access path b/w the data.

Good vs. Bad Design: – Poor design results in unwanted data redundancy – Poor design generates errors leading to bad decisions

Introduction to different designs: • Hierarchical database model, • Network database model, • Relational database model, • Object oriented database model, • Multidimensional database model.

Hierarchical database Architecture: •Logically represented by an upside down tree •Each parent can have many children •Each child has only one parent

Continued……. • It is a pointer based model • Organizes data in a tree-like structure • Stores data in tables and views relationships as links • Supports one-to-many parent-child relationships • Prevalent in large legacy systems

– Dominant in 1970s , when we used mainframe system with large databases

Advantages – – – –

Conceptual simplicity Database security and integrity Data independence Efficiency

Disadvantages: – Complex implementation: Database design was complicated – Difficult to manage – Lack of standards – Complex pointer based organization – Less flexible compared to RDBMS – Lack support for English languagelike queries

Network Database Model (1:M)

• Each record can have multiple

parents – Composed of sets – Each set has owner record and member record – Member may have several owners

Continue… • Depicts data logically as many-to-

many relationships • Organizes data in tables and views relationships as links • It is also a pointer based model

• Access via multiple pathways • Flexible, powerful

Advantages: – – – – – –

Conceptual simplicity Handles more relationship types Data access flexibility Promotes database integrity Data independence Conformance to standards

Disadvantages: Complex pointer based organization Less flexible compared to RDBMS Lack support forEnglish language-like queries

Relational Database Model • Was introduced in 1970 by Dr. E. F. Codd (of • •

IBM) Commercial relational databases began to appear in the 1980s Today relational databases have become the dominant technology for database management

• Perceived by user as a collection of tables for • •

data storage Tables are a series of row/column intersections Tables related by sharing common entity

Relational Database Model……….

Advatages – Improved conceptual simplicity – Easier database design, implementation, management, and use – Query capability with SQL – Powerful database management system Disadvantages: Substantial hardware and system software overhead Poor design and implementation is made easy

Object-Oriented Databases Uses an object-oriented data model Can store instructions Handles unstructured data Photographs, audio, video Data is organized using – Attributes Objects – Methods Classes Entities • Object-oriented DBMS: Stores data and procedures as objects that can be retrieved and shared automatically

• Object-relational DBMS: Provides capabilities of

A Comparison: The OO Data Model and the ER Model

Advantages: Database integrity Disadvantages: Disadvantages •Complex navigational data access •High system overhead slows transactions

Multidimensional Database Model • Often used in data warehouse applications. • By two ways it is viewed – Cube view – Star schema view

Cube view

• A cell contain data relevant to the intersection of all of its dimension values

Star schema view • At the center is a fact table, equivalent to the cell in the multi dimension view • This table contain all the raw attributes and a composite key made up of all the primary keys of all the surrounding dimension

The Development of Data Models

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