CS 338 Databases and Database Users INTRODUCTIONbbislimo/lectures/Introduction_to... · •Actors...
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Transcript of CS 338 Databases and Database Users INTRODUCTIONbbislimo/lectures/Introduction_to... · •Actors...
Major research
• Introduction
• An example
• Characteristics of the database approach
• Actors on the scene
• Workers behind the scene
• When not to use a DBMS
Outline
Major researchDiversity of Data
• Types of available data Text data Multimedia data Data in Social Networks Weather data Scientific data Web data Sensor data Stock data Enterprise data etc.
Major research Database
• Database logically coherent collection of data with inherent meaning
Some aspect of the real world (miniworld)
Designed and populated with data for a specific purpose
It can be of any size or complexity
Major researchDatabase Management System
Database Management System (DBMS)
General-purpose software system that facilitates the processes of defining, constructing, manipulating and sharing databases among various users and applications.
Major researchDatabase Management System
• Database Management System (DBMS)
General-purpose software system that facilitates the processes of defining, constructing, manipulating and sharing databases among various users and applications.
Additional features:
• System protection against hardware or software malfunction
• Maintenance of a database system over time
Major researchDatabase Management System
• Database Management System (DBMS)
General-purpose software system that facilitates the processes of defining, constructing, manipulating and sharing databases among various users and applications.
• DBMS examples IBM’s DB2, Microsoft’s Access and SQL Server, Oracle, MySQL, SAP’s SQL
Anywhere
Major researchDBMS Features
• Defining a database Specify data types, structures and constraints
Stored in the form of a database catalog
Meta-data: information stored inside a catalog
• Constructing a database Storing data on a storage medium
• Manipulating a database Querying a database to retrieve specific data
Update database to reflect miniworld changes
Major researchDBMS Features
• Sharing a database Multiple users and programs access concurrently
Application programs access the database • send queries
Transaction• An atomic unit of queries and updates that must be executed as a whole
Major research
• Used in pre-DBMS databases
• Each user defines and implements the files needed for a specific software application
• Data definition is part of the application programming
• Change of records structure requires change of file access programs
• As the application base grows many shared files
a multitude of file structures
a need to exchange data among applications
File Processing
Major research
• Database approach Self-describing nature of a database system
• Description of database structure => Catalog
Insulation between programs and data, and data abstraction• Conceptual representation of data (data model)
• Storage and implementation details hidden
Support of multiple views of data for different user types
Sharing data and multiuser transaction processing• Concurrency control of DBMS => correct execution of transactions
Characteristics of the Database Approach
Major research
• Database Administrators Authorize access to the database (DB)
Coordinate and monitor its use
Acquire software and hardware resources as needed
• Database Designers Understand requirements of database users
Identify data to be stored in the DB
Choose appropriate structures to represent the data
Actors on the Scene
Major research
• End Users Require access for querying, updating and generating
reports
Casual end users• Use sophisticated query interface
• Occassionaly access the DB, may ask different information each time
Naive or parametric end users• Constant query and update of the DB (canned transactions)
• e.g. Available through mobile apps
Sophisticated End Users• Familiarize with the DBMS features to implement their own
applications with specific requirements
Actors on the Scene
Major research
• End users Standalone Users
• Maintain personal databases by using ready-made program packages which inlcude menu and graphic-based interfaces
• System analysts Determine requirements of end users to develop
specifications for canned transactions
• Application programmers Implement these specifications as programs, maintain the
canned transactions
Actors on the Scene
Major research
• DBMS system designers and implementers Design and implement the DBMS modules and interfaces as a software
package
• Tool developers Design and implement tools that facilitate database modeling and
design, database system design
• Operators and maintenance personnel Responsible for hardware and software environment running and
maintenance (for the DB system)
Workers behind the Scene
Major research
• When there exist high overhead costs of using a DBMS
• Customized database applications are more desirable in the following cases: Simple, well-defined database applications are not expected to
change at all
Stringent, real-time requirements for some applications may not be met (reason: DBMS overhead)
No multiple users access to data
Embedded systems with limited storage capacity (DBMS would not fit)
• Examples CAD tools, GIS, communication and switching systems
When Not to Use a DBMS