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.
What is physical level abstraction?
describes complex low level data structures in detail
Which level of abstraction is the lowest/most complex?
Physical
which abstraction level describes the entire database in terms of a small number of relatively simple structures
Logical
How is abstraction done in a logical level
by describing what is stored and the relationship among the data
View level abstraction
Highest level of abstraction which describes only part of the entire database
Which level of abstraction is used to simplify user interaction?
View level
Prevention of users form accessing certain parts is done by which level of abstraction?
View level
Benefits of data abstraction:
–Reduce complexity
–Provide a level of security
–Provide a mechanism to customize the appearance of the database
–Present a consistent, unchanging picture of the structure of the
database, even if the underlying database structure is changed (
Abstraction)
Advantages of DBS
–Control of data redundancy
–Data consistency
–More information from the same amount of data
–Sharing of data
–Improved data integrity
–Improved security
–Enforcement of standards
–Economy of scale
–Improved data accessibility and responsiveness
–Increased productivity
–Improved maintenance through data independence
–Increased concurrency
–Improved backup and recovery services
Disadvantages of DBS
–Complexity
–Size
–Cost of DBMS
–Additional hardware costs
–Cost of conversion
–Performance
–Higher impact of a failure
What does a Data administrator aka data analyst do?
–Processing data into a data model
–figure out which data is relevant to be stored in the database
–Overall management of data resources
Creating and updating the database is whose job?
DBA
What does a database administrator do?
–Creating, maintain, backup, optimize the database and ensures the safety
– Integrate database to applications
What is aka Database programmer /database coordinator
DBAdmin
What do logical database designers do?
identify data that is to be stored (entity with attributes, relationship between the entities, constraints on the entities)
Who should have a thorough and complete understanding of the organization’s data and constraints.
logical db designers
the types of database designers
Physical and logical
Which DB designers decide how the logical DB design is physically realized?
Physical database designers
Responsibilities of physical DB designers
–Map logical database design into a set of integrity constraints
–Select specific storage structures and access methods for the data to achieve good performance.
Applications developers are…
developers that implement applications programs which provide functionality to the end users, only once after the DB is implemented.
Responsibilities of application developers
–Designing and developing database applications
–translate the requirements of the software into programming code
–maintain and update applications
End users
The “clients” , DB is designed to serve their needs.
Clients familiar with the structure of the database and the facilities offered by the DBMS are called
Sophisticated end users
Uses who use existing applications(online library system, ATM…) to interact with the database are called
Naive users
Roles in DB environment
DAdmin, DBAdmin, DB designers, App developers, End users
