IS 341
Database Administration

	Keith Vander Linden

"All our knowledge brings us..."

	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

Introduction

	This course     (http://cs.calvin.edu/IS/341/)
	An example information system
	Definitions & Characteristics (chapter 1)
	History of information systems
	Perspectives

An Example Information System

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

Data

	Data comprises entity classes, attributes and relationships:

A Data Hierarchy

Persistence

	Most data outlive the programs that operate on them.
	The DBMS must be able to store and retrieve this data.

Database Size

	Massive amounts of data are stored in databases.
	How massive?
		A comparison:
			http://www.cacr.caltech.edu/~roy/dataquan/ (a local copy)

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

Efficiency

	The operations on the data must be efficient.
	The data must be stored efficiently.

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

Safety

	The DBMS must protect the integrity of the database

Information Systems

	Collecting information
	Managing information
	Using information

When not to use databases

	When the hardware/software cost of a database system is too high for the application.

Database Systems History

Flat-File Databases

	These are simple file-based programs.
	Relationships are not stored explicitly.

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()

Example: 1-to-many

Example: many-to-many

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.

Example: many-to-many

Relational Databases

	Proposed in 1970 by E.F. Codd
	Offered in commercial systems the 1980’s (e.g., IBM’s DB2)

Object-Oriented Databases

	Databases based on ideas from object-oriented programming.
	Gemstone from Servio (1987)

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

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