Unit 1 Flashcards
On y va !
Critical raw asset that requires to be processed
Data
The process of ingesting, organizing and maintaining data (collected by an organization).
Data Management
Different levels of developing data management
Three. Manual, Traditional file based and Database approaches.
Which approach uses data retrieval by cabinet, file and information hierarchy? (could have an indexing system)
Manual
Limitations of Manual approach
Prone to error
Difficult to update, retrieve, integrate
It is difficult to compile information
Limited to small size information
Cross referencing is difficult
Which approach stores data in permanent files and uses different applications to retrieve and record files?
File based
Which approach uses different application programs which manage its own sets of data?
File based
Limitations of file based
- Redundancy
–the same information may be duplicated in several places (files) resulting to higher storage and access cost
Inconsistency
–the various copies of the
same data may no longer agree - Difficulty accessing data
–users being unaware of potentially useful data in other programs so its inefficient and inconvenient - Data isolation
–hard to make a program to retrieve the appropriate data - Data dependence
–change in the data structure need to changes the program
–physical structure and storage are defined in the application code
5.Incompatible file formats
–Programs might written in different languages, and so cannot easily access each other’s files
6. Fixed Queries/Proliferation of app programs
–programs are specific and new things require new programs
7.Security problems (hard to set security)
What is data isolation?
determines when and how changes made by one operation become visible to other concurrent users and systems
The ability of the database to allow multiple users access
to the same record without adversely affecting transaction processing
Concurrency
Two main reasons of File based was mauvais
data is stored in application programs instead of separately
no control over access and manipulation of data beyond application programs
Repository of related data that supports efficient data maintenance
Database
What is a Database management system?
Software system that enables user to use a computerized database
Interface between application programs and data files
Separates the logical and physical view
What is a database system?
collection of interrelated files and set of programs that allow users to access and modify these files
Provides a layer of abstraction
DBMS + data + maybe applications
Components of a database system
Hardware(multiple or single computers)
Software (the DBMS,OS and the network software)
Data( contains operational and meta data)
Procedures ( instructions of the database)
People (professional and end users)
The three levels of data abstractions:
Physical, logical and view level.