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Outline of Discussion

Database Technology: Achievements and Opportunities Dr M Saraee Dept. of Electrical and Computer Engineering Isfahan University of Technology. Outline of Discussion. Why do we need databases Database Systems: Past, Present and Future Overview of New Approaches. File-based Systems.

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Outline of Discussion

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  1. Database Technology:Achievements and OpportunitiesDr M Saraee Dept. of Electrical and Computer Engineering Isfahan University of Technology

  2. Outline of Discussion • Why do we need databases • Database Systems: Past, Present and Future • Overview of New Approaches

  3. 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.

  4. 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.

  5. Database Management System (DBMS)

  6. 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!

  7. Enforcing Constraints • With the File-based Systemsthere 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. A typo gives Roberta Wickham a GPA of 44.00

  8. Scalability • The File-based Systemsold 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!

  9. Query Expressiveness • The File-based Systemswould 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”

  10. 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!

  11. Different Views • The File-based Systemonly 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…

  12. 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.

  13. 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.

  14. Crash Recovery • Suppose I am editing my text file and the system crashes! • A DBMS is able to guarantee 100% recovery from system crashes.

  15. Roles in the Database Environment • Data Administrator (DA) • Database Administrator (DBA) • Database Designers (Logical and Physical) • Application Programmers • End Users (native and sophisticated)

  16. Database Systems: Achievements • Relational Database Systems • Transaction Management • Distributed Relational Database Systems

  17. Database Systems: Current Research • Object-Oriented DBMS • Object-Relational DBMS • Support for New Data Types • temporal data • spatial data • Transaction Processing

  18. Technology vs Functionality Matrix Functionality Active Temporal Multimedia Geographical SpatioTemporal Technology Relational Object-Oriented Interoperable Combine functionality from existing technology Add functionality to existing technology

  19. Database Systems: New Applications • Earth Observation Data • Electronic Commerce • Health-Care Information Systems • Digital Publishing • Collaborative Design

  20. 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.

  21. 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

  22. 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

  23. 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 databasesa distributed system should look exactly like a nondistributed system

  24. 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 arereactive • They monitor conditions defined on states of the database, and then, once these conditions occur, they invoke specified actions.

  25. Active Database Components • The rule base WHEN event IF condition THEN action • The database • The inference mechanism (rule manager) • The user interface

  26. event event UoD UoD UoD i i+1 i-1 IS IS IS i i-1 i+1 T+1 T - 1 T time axis Information Systems and Time

  27. 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

  28. 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?

  29. Conclusions • 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 Information Management

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