Concepts of Database Management, Fifth Edition Chapter 9: Database Management Approaches

Objectives Describe distributed DBMSs Discuss client/server systems Define data warehouses and explain their structure and access Discuss the general concepts of object- oriented DBMSs Concepts of Database Management, 5th Edition

Objectives Summarize the impact of Web access to databases Provide a brief history of database management Describe the network and hierarchical data models Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

Figure 9.1: Communications Network Concepts of Database Management, 5th Edition

Characteristics of Distributed DBMSs Homogeneous Same local DBMS at each site Heterogeneous At least two sites with different DBMSs Concepts of Database Management, 5th Edition

Characteristics of Distributed DBMSs (con’t.) 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 Concepts of Database Management, 5th Edition

Unfragmented Parts Table Concepts of Database Management, 5th Edition

Fragmented Parts Table Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

Rules for Distributed Databases Local autonomy No reliance on a central site Continuous operation Location transparency Fragmentation transparency Replication transparency Concepts of Database Management, 5th Edition

Rules for Distributed Databases (con’t.) Distributed query processing Distributed transaction management Hardware independence Operating system independence Network independence DBMS independence Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

Client/Server Systems Figure 9.4: Client/Server Systems Concepts of Database Management, 5th Edition

Figure 9.5: Two-Tier Client/Server Architecture Concepts of Database Management, 5th Edition

Figure 9.6: Three-Tier Client/Server Architecture Concepts of Database Management, 5th Edition

Advantages of Client/Server Systems Lower network traffic Improved processing distribution Thinner clients Greater processing transparency Concepts of Database Management, 5th Edition

Advantages of Client/Server Systems (con’t.) Increased network, hardware, and software transparency Improved security Decreased costs Increased scalability Concepts of Database Management, 5th Edition

Triggers and Stored Procedures 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 Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

Data Warehouse Architecture Figure 9.7: Data Warehouse Architecture Concepts of Database Management, 5th Edition

Data Warehouse Structure Figure 9.8: Data Warehouse Structure Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

Data Cube Representation Figure 9.9: Data Cube Representation Concepts of Database Management, 5th Edition

Slicing on Time Dimension Figure 9.11: Slicing on Time Dimension Concepts of Database Management, 5th Edition

Dicing on Part Dimension Figure 9.12: Dicing on Part Dimension Concepts of Database Management, 5th Edition

Rules for OLAP Systems Multidimensional conceptual view Transparency Accessibility Consistent reporting performance Client/server architecture Generic dimensionality Concepts of Database Management, 5th Edition

Rules for OLAP Systems Dynamic sparse matrix handling Multiuser support Unrestricted, cross-dimensional operations Intuitive data manipulation Flexible reporting Unlimited dimensions and aggregation levels Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

Figure 9.19: Class Diagram for Premiere Products Concepts of Database Management, 5th Edition

Class Diagram with Constraints Figure 9.20: Class Diagram with Constraints Concepts of Database Management, 5th Edition

Generalization and a Constraint Figure 9.21: Class Diagram with a Generalization and a Constraint Concepts of Database Management, 5th Edition

Rules for OODBMSs Complex objects Object identity Encapsulation Information hiding Types of classes Inheritance Late binding Concepts of Database Management, 5th Edition

Rules for OODBMSs (con’t.) Computational completeness Extensibility Persistence Performance Concurrent update support Recovery support Query facility Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

Figure 9.22: Web Access to Databases Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

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 Concepts of Database Management, 5th Edition

Summary Distributed databases physically fragment a database across many parts of a DBMS, but they must maintain reasonable transparency Most applications built around a DBMS will use a client-server architecture, involving at least two tiers, but more typically three Data warehouses are specialized DBMS products that allow users to view the data in more than two dimensions, typically three Concepts of Database Management, 5th Edition

Summary (con’t.) Object Oriented databases provide an encapsulated view by merging data with their operations, fitting with modern programming architectures Web access is common way to access data in a DBMS Hierarchical and network data models are two models of how users perceive a DBMSs structure and operation Concepts of Database Management, 5th Edition