IS 341 Database Administration Keith Vander Linden © 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 © Keith Vander Linden, 2005
3 Introduction ● This course (http: //cs. calvin. edu/IS/341/) ● ● An example information system Definitions & Characteristics History of information systems Perspectives (chapter 1) © 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 © 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 © Keith Vander Linden, 2005
6 Data comprises entity classes, attributes and relationships: Customers ID name address … Suppliers ID name address m … 1 m Products ID name price … m © Keith Vander Linden, 2005
7 A Data Hierarchy Database File Record Field Character/String/Number Bit © 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. © 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/ (a local copy) © 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 – © Keith Vander Linden, 2005
11 Efficiency ● ● The operations on the data must be efficient. The data must be stored efficiently. © 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 – © Keith Vander Linden, 2005
13 Safety ● The DBMS must protect the integrity of the database © Keith Vander Linden, 2005
14 Information Systems ● Collecting information ● Managing information ● Using information © 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. © Keith Vander Linden, 2005
16 Database Systems History Time Period Type 1940’s Number crunching 1950’s & 60’s Flat file early 1960’s Hierarchical late 1960’s Network 1970’s & 1980’s Relational 1990’s & 2000’s Object-Oriented © Keith Vander Linden, 2005
17 Flat-File Databases ● These are simple file-based programs. 01 02 tnt 250 missile 4000000 … … 03 35 … … ● umbrella … … … Relationships are not stored explicitly. Image from wilecoyote. cartooncountry. com July, 2003 © 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: – get. Next. Within. Parent(), insert(), replace() © Keith Vander Linden, 2005
19 Example: 1 -to-many Suppliers Vander Linden Acme Products Giant Cannon TNT Missile Little umbrella How it is stored on disk Acme cannon tnt missile umbr. Sears boots Image from wilecoyote. cartooncountry. com July, 2003 © Keith Vander Linden, 2005
20 Example: many-to-many Products Vander Linden missile Customers John Wile E Coyote Mary Aaron Virtual Products widget gadget Image from wilecoyote. cartooncountry. com July, 2003 © 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. © Keith Vander Linden, 2005
22 Example: many-to-many missile 1 cannon 2 1 Mary umbrella 2 1 Wile E Coyote Image from wilecoyote. cartooncountry. com July, 2003 © 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 DB 2) © Keith Vander Linden, 2005
24 Object-Oriented Databases ● ● Databases based on ideas from objectoriented programming. Gemstone from Servio (1987) © 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 © Keith Vander Linden, 2005
26 A Christian Perspective? ● Why do we do all this stuff? – ● What’s the Big Idea to proliferate or enhance creation Is any of it uniquely Christian? – Not really, but both the development and use of information systems have implications © Keith Vander Linden, 2005
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