RelationalDBDesign 





Network Topology   «Prev 

With distributed databases, there is no reliance on a central site

Ideally, all sites are equally remote, and no one site has governing authority over another.
Each site retains its own Oracle data dictionary and table security.
A data dictionary is a set of metadata that contains definitions and representations of data elements. Within the context of a DBMS, a data dictionary is a read-only set of tables and views. Amongst other things, a data dictionary holds the following information:

  1. Precise definition of data elements
  2. Usernames, roles and privileges
  3. Schema objects
  4. Integrity constraints
  5. Stored procedures and triggers
  6. General database structure
  7. Space allocations



Distributed database systems provide information on the networking, configuration, security, and design of systems. Any organization that uses the Oracle relational database management system (RDBMS) probably has multiple databases. There are a variety of reasons why you might use more than a single database in a distributed database system:
  1. Different databases may be associated with particular business functions, such as manufacturing or human resources.
  2. Databases may be aligned with geographic boundaries, such as a very large database at a headquarters site and smaller databases at regional offices.
  3. Two different databases may be required to access the same data in different ways, such as an order entry database whose transactions are aggregated and analyzed in a data warehouse.
  4. A busy internet commerce site may create multiple copies of the same database to attain horizontal scalability.
  5. A copy of a production database may be created to serve as a development test bed.