Lecture02-FileSystems

8/3/2019 Lecture02-FileSystems

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Overview

Manual File Systems

Computerized File Systems

Problems with File System Processing DBMS Functions



Manual File Systems

File systems were set up to handle corebusiness task efficiently

At early stage, all file system were manual

system. A system of storing and keep tracks of

records in file folders and filling cabinet.

Efficient when amount of records are small.

Complexity and difficulty to track datastored increase when the repositoryincreases.



Computerized File Systems

Generating reports from manual file systemwas slow and cumbersome.

Computer-based system that keep track data

and produce required report is created. Initially, computer file systems resembled

manual systems

As number of files increased, file systemsevolvedy Each file used its own application program to store,

retrieve, and modify data

y Each file was owned by individual or department thatcommissioned its creation



Basic File Terminolog y



Problems with File System

Processing Computerized file system improved the

manual file system.

However, challenges exists for DataProcessing specialists:

y Lengthy development time

y Difficult of getting quick answer

y Complex system administrationy Lack of security and limited file sharing

y Extensive programming



Limitation of File System

Processing

Structural and Data Dependencey Structural independence: possibility of changing

the file structure without affecting the applicationprogram¶s ability to access the data.

Data Redundancyy When the same data are stored unnecessarily at

different place

y Causes:

Poor data security

Data inconsistency

Data anomalies



Limitation of File System

Processing (2) Lack of Design and Data-Modeling Skills

y Forcing data into specify data structure

causes poor data design.

y Leads to large degree of data redundancy in

some data.

y Data modeling skills are vital part of design

process

y Data modeling is the most common method

of documenting database design



File Systems in using Database

When Database were introduced,

people replace file system with database

Data and record fields are store inside

the database, no more file documents

With Content Management System (like

moodle), Virtual File system are more

and more popular.



DBMS Functions

Data Dictionary Management

Data Storage Management

Data Transformation and Presentation

Security Management Multiuser access control

Backup and recovery management

Data integrity management

Data access languages and applicationprogramming interface

Database Communication Interfaces

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Lecture02-FileSystems