The University of Akron Dept of Business Technology Computer Information Systems Database Management Approaches 2440: 180 Database Concepts Instructor: Enoch E. Damson

Distributed Databases Computers at various sites Connected with communications network Distributed database is single logical database physically divided among networked computers DDBMS supports and manipulates distributed databases Database Management Approaches 2

Characteristics of Distributed DBMSs Homogeneous Same local DBMS at each site Heterogeneous At least two sites with different DBMSs Database Management Approaches 3

Characteristics of Distributed DBMSs… Location transparency User feels as though entire database is at their site Replication transparency User unaware of behind the scenes replication of the data Fragmentation transparency Logical object divided among various locations Database Management Approaches 4

Advantages of Distributed Databases Local control of data Possible legal reasons for local control over data used in a particular geographic region Increased database capability Added system availability Though parts of a database may not be accessible, transactions can still occur, increasing overall availability of the database Added efficiency Smaller tables are faster to query Database Management Approaches 5

Disadvantages of Distributed Databases Problems updating replicated data More complex query processing More complex treatment of concurrent update More complex recovery measures More difficult management of the data dictionary More complex database design Database Management Approaches 6

Rules for Distributed Databases Local autonomy No reliance on a central site Continuous operation Location transparency Fragmentation transparency Replication transparency Database Management Approaches 7

Rules for Distributed Databases… Distributed query processing Distributed transaction management Hardware independence Operating system independence Network independence DBMS independence Database Management Approaches 8

Client-Server Systems Tiered approach to developing systems Typical systems will implement two tiers Client Server Server manages all access to data Client consults server for most processing Some systems almost totally abstract the client from any processing by introducing a middle tier to handle all logic or processing Database Management Approaches 9

Advantages of Client/Server Systems Lower network traffic Improved processing distribution Thinner clients Greater processing transparency Database Management Approaches 10

Advantages of Client/Server Systems… Increased network, hardware, and software transparency Improved security Decreased costs Increased scalability Database Management Approaches 11

Triggers and Stored Procedures Triggers Actions that occurs automatically in response to a particular database operation Created by programmers Use special SQL statements Stored Procedures Collection of SQL statements compiled and optimized by DBMS Improves performance Database Management Approaches 12

Data Warehouses Subject-oriented, integrated, time-variant, nonvolatile collection of data in support of management’s decision-making process Used for analysis of existing data Resolves performance issues suffered by operational RDBMSs and OLTPs Database Management Approaches 13

On-Line Analytical Processing Optimized to work with data warehouses Used to answer questions Allows users to perceive data as a multidimensional data cube Slice and dice Drill down Roll Up Data mining Database Management Approaches 14

Rules for OLAP Systems Multidimensional conceptual view Transparency Accessibility Consistent reporting performance Client/server architecture Generic dimensionality Database Management Approaches 15

Rules for OLAP Systems Dynamic sparse matrix handling Multiuser support Unrestricted, cross-dimensional operations Intuitive data manipulation Flexible reporting Unlimited dimensions and aggregation levels Database Management Approaches 16

Object-Oriented DBMS (OODBMS) System in which data and methods operating on that data are encapsulated into objects Store graphics, drawings, video, sound, and other complex objects called binary large objects (BLOBs) General concepts Objects and classes Methods and messages Inheritance Database Management Approaches 17

Unified Modeling Language (UML) Models various aspects of software development for OO systems Includes several types of diagrams Class Use Case State Sequence Activity Collaboration Component Database Management Approaches 18

Database Management Approaches 19 Class Diagram with Constraints

Database Management Approaches 20 Class Diagram with a Generalization and a Constraint

Rules for OODBMSs Complex objects Object identity Encapsulation Information hiding Types of classes Inheritance Late binding Database Management Approaches 21

Rules for OODBMSs… Computational completeness Extensibility Persistence Performance Concurrent update support Recovery support Query facility Database Management Approaches 22

Web Access to Databases Electronic Commerce Conducting business on the Internet Business to Business Business to Consumer Internet facilitating better access to data Extensible Markup Language (XML) Key technology to data interchange between systems Database Management Approaches 23

History of Database Management Early systems GUAM, DL/I, IMS, IDS, IDMS Relational products DB2, Oracle, Sybase, Paradox, dBASE, Access, MySQL, SQL Server OODBMSs Gemstone, Objectivity/DB, Versant ORDBMSs Database Management Approaches 24

Hierarchical and Network Databases Data models have two components, structure and operations Structure is how users perceive data to be structured Operations are facilities given to users to interact with data Users perceive a network model database as a collection of record types and relationships Users perceive a hierarchical model as a collection of hierarchies or trees Database Management Approaches 25