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Donald K. Burleson
Oracle Tips |
Oracle Database
Distribution
The computers, or nodes in a
distributed database environment, will act as both clients and
servers depending upon whether they are requesting data from another
database on a different node or providing data to a different node
as it is requested.
Each site is autonomous, that is, managed independently. The
databases are distinct, separate entities that are sharing their
data. The benefits of site autonomy are:
* The various databases cooperating in the distributed environment
can mirror the local organization’s needs and desires. This is
especially useful at sites where there may be two organizations that
need to share some, but not all, data. An example would be two
aerospace companies cooperating on the space platform. They may need
to share data about design but not want to share financial
information.
* Local data is controlled by the local database administrator. This
limits the responsibility to a manageable level.
* Failure at one node is less likely to affect other nodes. The
global system is at least partially available as long as a single
node of the database is active. No single failure will halt all
processing or be a performance bottleneck. For example, if the
Pittsburgh node goes down, it won’t affect the Omaha node, as long
as Omaha doesn’t require any of Pittsburgh’s data.
* Failure recovery is on a per-node
basis.
* A data dictionary exists for each local database.
* Nodes can upgrade software independently, within reason.
As DBA you will need to understand the structures and limits of the
distributed environment if you are required to maintain a
distributed environment. The features of a two-phase commit, as well
as naming resolution and the other distributed topics, will be
covered in Chapter 14. Figure 1.3 shows a distributed database
structure.
This is an
excerpt by Mike Ault’s book “Oracle
Administration & Management”. If you want more current Oracle tips
by Mike Ault, check out his new book “Mike
Ault’s Oracle Internals Monitoring & Tuning Scripts” or
Ault’s Oracle Scripts Download.
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