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Type of Data to Store

Type of Data◦Raw data◦Pre-processed◦Compressed

Frequency of Data Storage for Sensor Data◦Tradeoff between precision and quantity

Database Types / Data Models

RelationalOOHybrid (Object-Relational)TemporalDeductiveOthers

◦Spatial, …

Data Representations

Relational◦We all know…flat tables of atomic attributes

with foreign key relationshipsOO

◦Complex data reps multivalued, composite

Temporal◦Relational model: add valid start, end dates to

each table (versions of info and when valid)◦Includes time, events, durations…

Operations

DDL/DML (data def/manip languages)◦SQL◦OQL

Update operations◦Built-in insert, delete, update◦Stored procedures for triggers, active (ECA)

rules

Example Operations for Temporal Databases

INCLUDES◦Rows valid in a certain time period

BEFORE/AFTER a time conditionSet operations

◦Union, intersection of 2 time periods

Distributed vs. Centralized

Centralized database can produce a bottleneck ◦Large volume of data input◦Large database◦Large volume of queries

In distributed databases, data consistency, replication, and retrieval can be more problematic◦Consistency of schemas◦Retrieval in case the data location is not known◦Communication overhead to ensure database

consistency

Types of Database Systems

Commercial◦DB2◦Empress◦ Informix◦Oracle◦MS Access◦MS SQL◦Sybase

Free◦Berkeley DB◦PostgreSQL◦MySQL

Database System

Database:A collection of related data.

Data:Known facts that can be recorded and have an implicit meaning.

Database Management System (DBMS):A software package/system to facilitate theDefine, Construct, Manipulate and Share

functions of a computerized database.

Typical DBMS Functionality

Define a particular database in terms of its data types, structures, and constraints

Construct or Load the initial database contents on a secondary storage medium

Manipulate the database:◦ Retrieval: Querying, generating reports◦ Modification: Insertions, deletions and updates to its content◦ Accessing the database through Web applications

Share a database allows multiple users and programs to access the database simultaneously

Database system environment

Example

A UNIVERSITY database for maintaining information concerning students, courses, and grades in a university environment

We have:STUDENT file stores data on each studentCOURSE file stores data on each courseSECTION file stores data on each section of each courseGRADE_REPORT file stores the grades that students

receive PREREQUISITE file stores the prerequisites

Example of a simple database

Database manipulation

Database manipulation involves querying and updating

Examples of querying are:Retrieve a transcriptList the prerequisites of the “Database”

courseExamples of updating are:Enter a grade of “A” for “Smith” in

“Database” course

Advantages of using the DBMS approach

Restricting unauthorized access to dataProviding Storage Structures (e.g.

indexes) for efficient Query ProcessingProviding backup and recovery servicesProviding multiple interfaces to different

classes of usersRepresenting complex relationships

among data