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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