23-02-2011, 01:02 PM
presented by:
Asma Halabeia
[attachment=9017]
Distributed Database
Objectives
• To understand concept of DDB
●To know architecture for DDB
●To know the Rules of DDB
●To know types of DDB
●Compare adva & disadva
●Show example of DDBQ
Distributed database concept
Distributed database is collection of different data which belong logically to the same system but spread over the Site of computer network
Why need distributed DB
• Organizational and economic reason.
●Interconnection of existing database.
●Reduced communication overhead.
●Performance considerations.
●Reliability and availability.
A reference architecture of DDB
●global schema.
●fragmentation schema.
●allocation schema.
●local mapping schema.
Some levels may be missing depend on levels of transparency supported.
Reference Architecture for DDB
●●global schema: defines all the data which are contained in distribut database.
●fragment: each global relation can be split into several non overlapping portion.
●●fragmentation schema: the mapping between global relation and fragment.
●●allocation schema: define at which site a fragment located.
●●local mapping schema: depends on the type of DBMS .
Asma Halabeia
[attachment=9017]
Distributed Database
Objectives
• To understand concept of DDB
●To know architecture for DDB
●To know the Rules of DDB
●To know types of DDB
●Compare adva & disadva
●Show example of DDBQ
Distributed database concept
Distributed database is collection of different data which belong logically to the same system but spread over the Site of computer network
Why need distributed DB
• Organizational and economic reason.
●Interconnection of existing database.
●Reduced communication overhead.
●Performance considerations.
●Reliability and availability.
A reference architecture of DDB
●global schema.
●fragmentation schema.
●allocation schema.
●local mapping schema.
Some levels may be missing depend on levels of transparency supported.
Reference Architecture for DDB
●●global schema: defines all the data which are contained in distribut database.
●fragment: each global relation can be split into several non overlapping portion.
●●fragmentation schema: the mapping between global relation and fragment.
●●allocation schema: define at which site a fragment located.
●●local mapping schema: depends on the type of DBMS .
