15-10-2012, 01:48 PM
Distributed Database Management Systems
Distributed Database.ppt (Size: 1.7 MB / Downloads: 155)
The Evolution of Distributed Database Management Systems
Distributed database management system (DDBMS)
Governs storage and processing of logically related data over interconnected computer systems in which both data and processing functions are distributed among several sites
The Evolution of Distributed Database Management Systems (DDBMS)
Centralized database required that corporate data be stored in a single central site
Performance degradation as number of remote sites grew
High cost to maintain large centralized DBs
Reliability problems with one, central site
Dynamic business environment and centralized database’s shortcomings spawned a demand for applications based on data access from different sources at multiple locations
Business operations became more decentralized geographically
Competition at global level
Rapid technological change in computers
DDBMS Advantages
Data are located near “greatest demand” site
Faster data access
Faster data processing
Growth facilitation
Improved communications
Reduced operating costs
User-friendly interface
Less danger of a single-point failure
Processor independence
DDBMS Disadvantages
Complexity of management and control
Security
Lack of standards
Increased storage requirements
Greater difficulty in managing the data environment
Increased training cost
Distributed Processing vsDistributed Database
Distributed processing – a database’s logical processing is shared among two or more physically independent sites that are connected through a network
One computer performs I/O, data selection and validation while second computer creates reports
Uses a single-site database but the processing chores are shared among several sites
Distributed database – stores a logically related database over two or more physically independent sites. The sites are connected via a network
Database is composed of database fragments which are located at different sites and may also be replicated among various sites
Characteristics of a DDBMS
Application interface
Validation
Transformation
Query optimization
Mapping
I/O interface
Formatting
Security
Backup and recovery
DB administration
Concurrency control
Transaction management
DDBMS Components
Must include (at least) the following components:
Computer workstations
Network hardware and software
Allows all sites to interact and exchange data
Communications media
Carry the data from one workstation to another
Transaction processor (application processor or transaction manager)
Software component found in each computer that receives and processes the application’s requests data
Data processor or data manager
Software component residing on each computer that stores and retrieves data located at the site
May even be a centralized DBMS
Communications between the TPs and DPs is made possible through a set of protocols used by the DDBMS
Distributed Database.ppt (Size: 1.7 MB / Downloads: 155)
The Evolution of Distributed Database Management Systems
Distributed database management system (DDBMS)
Governs storage and processing of logically related data over interconnected computer systems in which both data and processing functions are distributed among several sites
The Evolution of Distributed Database Management Systems (DDBMS)
Centralized database required that corporate data be stored in a single central site
Performance degradation as number of remote sites grew
High cost to maintain large centralized DBs
Reliability problems with one, central site
Dynamic business environment and centralized database’s shortcomings spawned a demand for applications based on data access from different sources at multiple locations
Business operations became more decentralized geographically
Competition at global level
Rapid technological change in computers
DDBMS Advantages
Data are located near “greatest demand” site
Faster data access
Faster data processing
Growth facilitation
Improved communications
Reduced operating costs
User-friendly interface
Less danger of a single-point failure
Processor independence
DDBMS Disadvantages
Complexity of management and control
Security
Lack of standards
Increased storage requirements
Greater difficulty in managing the data environment
Increased training cost
Distributed Processing vsDistributed Database
Distributed processing – a database’s logical processing is shared among two or more physically independent sites that are connected through a network
One computer performs I/O, data selection and validation while second computer creates reports
Uses a single-site database but the processing chores are shared among several sites
Distributed database – stores a logically related database over two or more physically independent sites. The sites are connected via a network
Database is composed of database fragments which are located at different sites and may also be replicated among various sites
Characteristics of a DDBMS
Application interface
Validation
Transformation
Query optimization
Mapping
I/O interface
Formatting
Security
Backup and recovery
DB administration
Concurrency control
Transaction management
DDBMS Components
Must include (at least) the following components:
Computer workstations
Network hardware and software
Allows all sites to interact and exchange data
Communications media
Carry the data from one workstation to another
Transaction processor (application processor or transaction manager)
Software component found in each computer that receives and processes the application’s requests data
Data processor or data manager
Software component residing on each computer that stores and retrieves data located at the site
May even be a centralized DBMS
Communications between the TPs and DPs is made possible through a set of protocols used by the DDBMS