The University of Akron Dept of Business Technology Computer Information Systems 2440: 180 Database Concepts Instructor: Enoch E. Damson Database Management Approaches Distributed Databases • Computers at various sites • Distributed database is single logical database physically divided among networked computers • DDBMS supports and manipulates distributed databases Database Management Approaches • Connected with communications network 2 Characteristics of Distributed DBMSs • Homogeneous • Heterogeneous • At least two sites with different DBMSs Database Management Approaches • Same local DBMS at each site 3 Characteristics of Distributed DBMSs… • Location transparency • Replication transparency • User unaware of behind the scenes replication of the data • Fragmentation transparency Database Management Approaches • User feels as though entire database is at their site • Logical object divided among various locations 4 Advantages of Distributed Databases • Local control of data • 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 Database Management Approaches • Possible legal reasons for local control over data used in a particular geographic region • Added efficiency • Smaller tables are faster to query 5 Disadvantages of Distributed Databases • Problems updating replicated data • More complex treatment of concurrent update • More complex recovery measures • More difficult management of the data dictionary Database Management Approaches • More complex query processing • More complex database design 6 Rules for Distributed Databases • Local autonomy • Continuous operation • Location transparency Database Management Approaches • No reliance on a central site • Fragmentation transparency • Replication transparency 7 Rules for Distributed Databases… • Distributed query processing • Hardware independence • Operating system independence Database Management Approaches • Distributed transaction management • Network independence • DBMS independence 8 Client-Server Systems • Tiered approach to developing systems • Typical systems will implement two tiers • Server • Server manages all access to data • Client consults server for most processing Database Management Approaches • Client • Some systems almost totally abstract the client from any processing by introducing a middle tier to handle 9 all logic or processing Advantages of Client/Server Systems • Improved processing distribution • Thinner clients • Greater processing transparency Database Management Approaches • Lower network traffic 10 Advantages of Client/Server Systems… • Improved security • Decreased costs Database Management Approaches • Increased network, hardware, and software transparency • Increased scalability 11 Triggers and Stored Procedures • Triggers • Created by programmers • Use special SQL statements • Stored Procedures • Collection of SQL statements compiled and optimized by DBMS • Improves performance Database Management Approaches • Actions that occurs automatically in response to a particular database operation 12 Data Warehouses • Used for analysis of existing data Database Management Approaches • Subject-oriented, integrated, time-variant, nonvolatile collection of data in support of management’s decision-making process • Resolves performance issues suffered by operational RDBMSs and OLTPs 13 On-Line Analytical Processing • Optimized to work with data warehouses • Allows users to perceive data as a multidimensional data cube • Slice and dice • Drill down Database Management Approaches • Used to answer questions • Roll Up • Data mining 14 Rules for OLAP Systems • Multidimensional conceptual view • Accessibility • Consistent reporting performance Database Management Approaches • Transparency • Client/server architecture • Generic dimensionality 15 Rules for OLAP Systems • Dynamic sparse matrix handling • Unrestricted, cross-dimensional operations • Intuitive data manipulation Database Management Approaches • Multiuser support • Flexible reporting • Unlimited dimensions and aggregation levels 16 Object-Oriented DBMS (OODBMS) • Store graphics, drawings, video, sound, and other complex objects called binary large objects (BLOBs) • General concepts • Objects and classes Database Management Approaches • System in which data and methods operating on that data are encapsulated into objects • Methods and messages • Inheritance 17 Unified Modeling Language (UML) • • • • • • • Class Use Case State Sequence Activity Collaboration Component Database Management Approaches • Models various aspects of software development for OO systems • Includes several types of diagrams 18 Database Management Approaches Class Diagram with Constraints 19 Database Management Approaches Class Diagram with a Generalization and a Constraint 20 Rules for OODBMSs • Complex objects • Encapsulation • Information hiding • Types of classes Database Management Approaches • Object identity • Inheritance • Late binding 21 Rules for OODBMSs… • Computational completeness • Persistence • Performance • Concurrent update support Database Management Approaches • Extensibility • Recovery support • Query facility 22 Web Access to Databases • Electronic Commerce • Business to Business • Business to Consumer • Internet facilitating better access to data • Extensible Markup Language (XML) Database Management Approaches • Conducting business on the Internet • Key technology to data interchange between systems 23 History of Database Management • Early systems • GUAM, DL/I, IMS, IDS, IDMS • DB2, Oracle, Sybase, Paradox, dBASE, Access, MySQL, SQL Server • OODBMSs Database Management Approaches • Relational products • Gemstone, Objectivity/DB, Versant • ORDBMSs 24 Hierarchical and Network Databases • 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 • Data models have two components, structure and operations 25