1 database technology: achievements and opportunities dr m saraee dept. of electrical and computer...
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Database Technology:Achievements and Opportunities
Dr M Saraee Dept. of Electrical and Computer Engineering
Isfahan University of Technology
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Outline of Discussion
Why do we need databases
Database Systems: Past, Present and Future
Overview of New Approaches
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File-based Systems
A collection of application programs that perform services for the end users (e.g. reports). Each program defines and manages its own data.
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Database / DBMS
Database: A shared collection of logically related data (and a description of this data), designed to meet the information needs of an organisation.
DBMS: A software system that enables users to define, create, and maintain the database and which provides controlled access to this database.
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Database Management System (DBMS)
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Why do we need database management systems?
• A Database Management System (DBMS) is a tool that allows to store, modify and query data.
However, we can store, modify and query data in a text file!
What can a DBMS do that we can’t do with the text file solution. File-based solution to manage data, stick it all in a
text file!
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Enforcing Constraints
A typo gives Roberta Wickham a GPA of 44.00
• With the File-based Systems there is no way to enforce integrity constraints on the data. In other words people can put bad data into the text file.• In contrast, a DBMS allows us to enforce all kinds of constraints. This really helps (but does not guarantee) that our data is correct.
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Scalability
• The File-based Systems old method, might work for small datasets. What happens when we have big datasets…
• Most real world datasets are so large that we can only have a small fraction of them in main memory at any time, the rest has to stay on disk.• Even if we had lots of main memory, with 32 bit addressing we can only refer to 4GB of data!
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Query Expressiveness
• The File-based Systems would allow us to search for keywords or certain numbers (slowly).• With a DBMS we can search with much more expressive queries. For example I can ask.. “Find all students whose GPA is greater than 2.5, and who don’t own a phone” or “what is the average GPA of the students”
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Query Expressiveness II
• We could write some program that might allow more expressive queries on my text file, but it would tied into the structure of our data and the operating system etc.. • With a DBMS we are completely isolated from the physical structure of our data. If we change the structure of our data (by adding a field, for example) or moving from a PC to a Mac, nothing changes at the front end!
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Different Views
• The File-based System only allows one view of the data.•With a DBMS we can arrange for different people to have different views of the data. For example, I can see everything, a student can see only his/her data, the TA can see…
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Concurrency
• Suppose we leave my text file on UNIX account, and weI log in and begin to modify it at the same time our TA is modifying it!
• A DBMS will automatically make sure that this kind of thing cannot happen.
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Security
• Suppose I leave my text file on UNIX account, and a student hacks in and changes their grades…
• A DBMS will allow multiple levels of security.
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Crash Recovery
• Suppose I am editing my text file and the system crashes!
• A DBMS is able to guarantee 100% recovery from system crashes.
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Roles in the Database Environment
Data Administrator (DA)Database Administrator (DBA)Database Designers (Logical and Physical)Application ProgrammersEnd Users (native and sophisticated)
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Database Systems: Achievements
Relational Database Systems
Transaction Management
Distributed Relational Database Systems
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Database Systems: Current Research
Object-Oriented DBMS– Object-Relational DBMS
Support for New Data Types– temporal data
– spatial data
Transaction Processing
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Technology vs Functionality Matrix
Relational
Object-Oriented
Technology
Active Multimedia GeographicalTemporal SpatioTemporal
Add functionality to existing technology
Add functionality to existing technology
Combine functionality from existing technology
Combine functionality from existing technology
Interoperable
Functionality
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Database Systems: New Applications
Earth Observation Data
Electronic Commerce
Health-Care Information Systems
Digital Publishing
Collaborative Design
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Earth Observation Data
The Earth Observing System (EOS) will gather data about the atmosphere, oceans and land.
NASA satellites have been launched from 1998 onwards
Data transmission is estimated to be 1/3 petabyte per year (1PB = 109 MB=1015 bytes)
EOS Data and Information System (EOSDIS) will support on-line access and maintenance of EOS data.
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Electronic Commerce
Needs support for browsing of catalogs and electronic purchasing of goods
Large number of consumers and suppliers
Database challenges– heterogeneous distributed information sources
– distributed authentication and fund transfers
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Health-Care Information Systems
Improve quality and quantity of health care
Needs support for medical records across hospitals, medical offices and insurance offices and across countries
Collection of historical information about a patient
Database challenges– integration of heterogeneous legacy information
– access control to preserve confidentiality of medical records
– intelligent interfaces to be used by health-care professionals
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Distributed Databases
A distributed database system consists of a collection of sites, connected together via some kind of communications network, in which
– each site is a database system in its own right, but
– the sites have agreed to work together (if necessary), so that a user at any site can access data anywhere in the network exactly as if the data was all stored at the user's own site
Fundamental principle of distributed databases
a distributed system should look exactly like a nondistributed system
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Active Databases
Relational Databases are passive
– They execute queries or database operations only when explicitly requested to do so by a user or an application program.
Active Databases are reactive
– They monitor conditions defined on states of the database, and then, once these conditions occur, they invoke specified actions.
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Active Database Components
The rule base
WHEN event IF condition THEN action
The database
The inference mechanism (rule manager)
The user interface
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Information Systems and Time
time axis
T - 1 T T+1
event event
UoDi-1
i-1IS
UoD i
iIS
UoD i+1
ISi+1
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Why Time Modelling?
Historical queries about past status
Trend analysis
Representation of retroactive or proactive changes
Version control and design management
Scheduling and planning requirements
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Time and IS Modelling
What was the salary of John Smith last year
What was the business policy for the Product Ordering process under the previous managing director
What is the history of the Product Promotion strategy?
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Knowledge Representation and Manipulation within a computer is the single most important challenge for IS
Databases are the main focus of this work and they are the most widely available technology outside operating systems
The next few years will see another rapid expansion of this area
Conclusions
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