DBMS Chapter 1 Flashcards
Traditional database application
information is stored and accessed is either textual or numeric.
Multimedia database systems
Includes pictures, audio, and video streams
Geographic information system (GIS)
Maps, weather data, satellite images
Real time/active database technology
Industrial and manufacture database processes
Database
Collection of related data
Data
Known facts that can be recorded and that have implicit meaning
Data warehouses and online analytical processing (OLAP)
Used to extract and analysis useful business information from very large databases to support decision making
Mini-world
Some aspect of the real world which is stored in a database
Ex: student grades/ transcripts
Database management systems (DBMS)
Collection of programs that enables users to create and maintain a database.
DBMS functionality:
Constructing, Manipulating, Shared access, Queries, Defining, Protection, Transactions
3 steps to making a database
Conceptual design = ERD
Logical design = Schema
Physical design = SQL
Database approach vs File-processing approach
■ Self-describing nature of a database system
■ Insulation between programs and data, and data abstraction
■ Support of multiple views of the data
■ Sharing of data and multi user transaction processing
Self-Describing Nature
A DBMS catalog stores the description of the database. The description is called meta-data. This allows the DBMS software to work with different databases
Insulating between programs and data
Called program-data independence. Allows changing data storage structures and operations without having to change the DBMS access programs
Data Abstraction
A data model is used to hide storage details and present the users with a conceptual view of the database
Support of multiple views of the data
Each user may see a different view of the database, which describes only the data of interest to that user
Sharing of data and multi-user transaction processing
Allowing a set of concurrent users to retrieve and to update the database. through concurrency control.
Concurrency control
Ensures that several users trying to update the same data do so in a so in a controlled manner so that the result of the updates is correct.
Transaction
Executing program that includes one or more database accesses, such as reading or updating of database records
Database Administration
Responsible for authorization access to the database, for coordinating and monitoring its use, acquiring software and hardware resources, controlling its use and monitoring efficiency of operations
Database designers
Define the content the structure, constraints, and function transaction against the database
End-users
Use data for queries, reports, update database content
Casual end-user
Use database occasionally when needed
Naive
Use well-defined function in the form against the database Ex: bank tellers
Sophisticated user
People familiar with the system capabilites
Stand-alone
Maintain personal databases using ready to use packaged applications Ex: tax programs user
Workers behind the Scene
DBMS system designers and implementer
Tool developers
Operators and maintenance personnel
System administration personnel.
Advantages of Using the Database Approach
- Controlling redundancy
- Sharing of data
- Restricting unauthorized access
- Providing persistent storage for program Objects
- Providing Storage Structures
- Providing backup and recovery services.
- Providing multiple interfaces to different classes of users.
- Representing complex relationships among data.
- Enforcing integrity constraints on the database.
- Drawing Inferences and Actions using rules
Buffering module
Used to copy data from disk to main memory
Index
Data structure used to disk search for records
Potential for enforcing standards
Standards refer to data item names, display formats, screens, report structures, meta-data (description of data) etc
Reduced application development time
incremental time to add each new application is reduced.
Flexibility to change data structures
Database structure may evolve as new requirements are defined.
Availability of up-to-date information
Very important for on-line transaction systems such as airline, hotel, car reservations.
Economies of scale
By consolidating data and applications across departments wasteful overlap of resources and personnel can be avoided.
When not to use DBMS
- High initial investment and possible need for additional hardware.
- Overhead for providing generality, security, concurrency control, recovery, and integrity functions.
When a DBMS may be unnecessary
- If the database and applications are simple, well defined, and not expected to change.
- If there are stringent real-time requirements that may not be met because of DBMS overhead.
- If access to data by multiple users is not required.
When no DBMS may suffice
- If the database system is not able to handle the complexity of data because of modeling limitations
- If the database users need special operations not supported by the DBMS.
