Oracle db replication

1
A Guide to the Process of Database Replication

• Replication is the process of maintaining and
  copying database objects such as tables in
  several databases that in total make up a
  complete distributed database system. Any changes
  made at one site or point are first captured and
  stored locally before being sent and applied in
  remote locations. A fully integrated feature of
  the Oracle server is Oracle replication which is
  not a separate server by itself.

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• The Oracle database provides Oracle db
  replication and other integration features that
  are critical for any organization and enterprise,
  regardless of the scale and size. Replication
  uses distributed database technology to share
  data among multiple sites. In such a database,
  data may be present in many locations but a
  specific table resides at only one location.

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• Why should you be using replication? Here are a
  few common reasons for doing so. 
• Performance  Replication balances activities
  over multiple sites and hence provides fast local
  access to shared data. Some users can access data
  on one server while others will have access to
  the same data in other servers. The process thus
  reduces the load on any one server and
  distributes it evenly. Again, users can access
  data from the replication site that is
  geographically closest to them, thereby reducing
  costs of access and increasing the speed of
  access. 

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• Availability  Replication enhances the
  availability of applications by offering
  alternate data access options. Even if one site
  becomes unavailable or temporarily disabled,
  users can continue to have access and even update
  data on the remaining locations. In a nutshell,
  replication provides an excellent standby
  database. 
• Reduction in network load  Replication
  dramatically reduces network load. This is
  because the process distributes data over
  multiple regional locations and applications can
  access them instead of depending solely on one
  central server. 

5

• Deploying bulk applications  As organizations
  grow in size they have to deploy many
  applications that require the capability to
  manipulate and use data. With Oracle db
  replication, deployment templates facilitate
  quick creation of multiple snapshot environments
  with the option to use variables to customize
  each snapshot to match specific needs. A
  deployment template for sales force automation,
  for example, could contain a range of variables
  for different sales regions and salespersons. 

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• Disconnected computing Snapshots, which are
  copies of a complete or partial target master
  table from a particular point in time, help users
  to work on a subset of a database while
  disconnected from the central database server.
  Afterwards, when a connection is established with
  the central server, users can refresh or
  synchronize snapshots on demand. Through refresh,
  the central database is updated with all their
  changes. Simultaneously, they receive all the
  changes that were made while they were
  disconnected. 
• An Oracle db replication environment can support
  both server-to-server replication and mass
  deployment and this enables integration into one
  consistent environment.