1. © Keith Vander Linden, 2005 IS 341 Database Administration Keith Vander Linden

2. © Keith Vander Linden, 2005 2 All our knowledge brings us nearer to our ignorance, All our ignorance brings us nearer to death, But nearness to death, no nearer to God. Where is the Life we have lost in living? Where is the wisdom we have lost in knowledge? Where is the knowledge we have lost in information? The cycles of Heaven in twenty centuries Bring us farther from God and nearer to the Dust. - T. S. Eliot, The Rock, 1934

3. © Keith Vander Linden, 2005 3 Introduction ● This course (http://cs.calvin.edu/IS/341/) (http://cs.calvin.edu/IS/341/) ● An example information system An example information system ● Definitions & Characteristics (chapter 1) Definitions & Characteristics ● History of information systems History of information systems ● Perspectives Perspectives

4. © Keith Vander Linden, 2005 4 An Example Information System Supports a small business database for a fictional company Find it on-line at: http://pella.calvin.edu/acme/Pages/acme.htm Image from www.acme.com July, 2003

5. © Keith Vander Linden, 2005 5 Definitions ● Database - a collection of related data that is persistent and too large to fit into main memory ● Database Management System – an automated system that maintains and provides multi-user access to a database, and whose operation is efficient, easy to use, and safe ● Information System – A system (i.e., people, machines, and/or methods) to collect, manage, and use data that represent information

6. © Keith Vander Linden, 2005 6 Data  Data comprises entity classes, attributes and relationships: Customers ID name address … Products ID name price … m m Suppliers ID name address … 1 m

7. © Keith Vander Linden, 2005 7 A Data Hierarchy Database File Record Field Character/String/Number Bit

8. © Keith Vander Linden, 2005 8 Persistence ● Most data outlive the programs that operate on them. ● The DBMS must be able to store and retrieve this data.

9. © Keith Vander Linden, 2005 9 Database Size ● Massive amounts of data are stored in databases. ● How massive? – A comparison: http://www.cacr.caltech.edu/~roy/dataquan/http://www.cacr.caltech.edu/~roy/dataquan/ (a local copy)(a local copy)

10. © Keith Vander Linden, 2005 10 Multiple Users ● The DBMS must support multi-user access. ● There are different types of users: – Administrators – Database designers – End users ● Each user should have: – their own view of the database – their own means of interacting with it

11. © Keith Vander Linden, 2005 11 Efficiency ● The operations on the data must be efficient. ● The data must be stored efficiently.

12. © Keith Vander Linden, 2005 12 Convenience ● The command languages and interfaces must be easy to use. ● Database applications must be insulated from changes to: – the structure of the data - data independence – the implementation of the commands – the physical location of the data

13. © Keith Vander Linden, 2005 13 Safety ● The DBMS must protect the integrity of the database

14. © Keith Vander Linden, 2005 14 Information Systems ● Collecting information ● Managing information ● Using information

15. © Keith Vander Linden, 2005 15 When not to use databases ● When the hardware/software cost of a database system is too high for the application.

16. © Keith Vander Linden, 2005 16 Database Systems History Time PeriodType 1940’sNumber crunching 1950’s & 60’sFlat file early 1960’sHierarchical late 1960’sNetwork 1970’s & 1980’sRelational 1990’s & 2000’sObject-Oriented

17. © Keith Vander Linden, 2005 17 Flat-File Databases ● These are simple file-based programs. ● Relationships are not stored explicitly. 01tnt…250 02missile…4000000 03umbrella…35 ………… Image from wilecoyote.cartooncountry.com July, 2003

18. © Keith Vander Linden, 2005 18 Hierarchical Databases ● Work at IBM: – GUAM, part of the Apollo program (1964) – IMS system (1968) ● Designed to exploit disk structure ● Good for 1-m relationships, bad for m-m ● Query language: – getNextWithinParent(), insert(), replace()

19. © Keith Vander Linden, 2005 19 Example: 1-to-many Vander Linden Acme Giant Cannon Suppliers TNTMissileLittle umbrella Products cannontntumbr.AcmeSearsbootsmissile How it is stored on disk Image from wilecoyote.cartooncountry.com July, 2003

20. © Keith Vander Linden, 2005 20 Example: many-to-many Vander Linden missile John Products Wile E CoyoteMaryAaron Customers widgetgadget Virtual Products Image from wilecoyote.cartooncountry.com July, 2003

21. © Keith Vander Linden, 2005 21 Network Databases ● CODASYL-DBTG (1971) ● less efficient, but handles many-many ● Query language: – a "navigation" language – commands: get (i.e., follow link), connect (i.e. make link) In both cases, the queries were written algorithmically.

22. © Keith Vander Linden, 2005 22 Example: many-to-many missileumbrellacannon MaryWile E Coyote 12211 Image from wilecoyote.cartooncountry.com July, 2003

23. © Keith Vander Linden, 2005 23 Relational Databases ● Proposed in 1970 by E.F. Codd ● Offered in commercial systems the 1980’s (e.g., IBM’s DB2)

24. © Keith Vander Linden, 2005 24 Object-Oriented Databases ● Databases based on ideas from object- oriented programming. ● Gemstone from Servio (1987)

25. © Keith Vander Linden, 2005 25 Database Trends ● Larger and larger databases: – Multimedia databases – Geographic Information Systems (GIS) – Distributed databases and Data-warehouses ● Smaller and smaller databases ● Continuously available, on-line databases

26. © Keith Vander Linden, 2005 26 A Christian Perspective? ● Why do we do all this stuff? – to proliferate or enhance creation ● Is any of it uniquely Christian? – Not really, but both the development and use of information systems have implications What’s the Big Idea