Oracle Advanced Replication .

1.  Advanced Replication can support both mass deployment
and server-to-server replication, enabling integration into a
single coherent environment.
 Advanced Replication can replicate data in environments
that use different releases of Oracle and in environments
that run Oracle on different operating systems.
Advanced Replication

2.  Replication - is the process of copying and maintaining
database objects, in multiple databases that comprise a
distributed database system. Changes applied at
 one site are captured and stored locally before being
forwarded and applied at each of the remote locations.
Advanced Replication is a fully integrated feature of the
Oracle server; it is not a separate server.
Replication uses distributed database technology to share
data between multiple sites, but a replicated database and
a distributed database are different. Replication means
that the same data is available at multiple locations.
 Availability, Performance: Replication provides fast, local
access to shared data because it balances activity over
multiple sites.
Advanced Replication can replicate data in environments
that use different releases of Oracle and in environments
that run Oracle on different operating systems.

3. Advanced Replication enables you to replicate the following
types of objects:
 ■ Tables
 ■ Indexes
 ■ Views and Object Views
 ■ Packages and Package Bodies
 ■ Procedures and Functions
 ■ User-Defined Types and Type Bodies
 ■ Triggers
 ■ Synonyms
 ■ Index types
 ■ User-Defined Operators
Basic components of a replication system, including
replication objects, replication groups, and replication sites.

4.  1.Oracle manages replication objects using replication groups. A replication
group is a collection of replication objects that are logically related make it
easier to
 administer many objects together. But each replication object can be a
member of only one replication group.
 2.Replication environments support two basic types of sites: master sites
and materialized view sites. One site can be both a master site for one
replication group and a materialized view site for a different replication
group.
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Every master group has exactly one master definition site. A replication
group's
 master definition site is a master site serving as the control center for
managing
 the replication group and the objects in the group.
A master site maintains a complete copy of all objects in a replication group,
while
 materialized views at a materialized view site can contain all or a subset of
the
 table data within a master group.

5.  Advanced Replication supports the following types of
replication environments:
 ■ Multi-master Replication
 ■ Materialized View Replication
 ■ Multi-master and Materialized View Hybrid
Configurations
Types of Replication Environments

6. Multimaster Replication

7.  Multimaster replication includes multiple master sites, where each master
site operates as an equal peer.
Materialized views can be based on master tables at master sites or on
materialized views at materialized view sites.
 Multimaster replication : (peer-to-peer or n-way replication), consists of
 multiple master sites equally participating in an update-anywhere model.
Updates
 made to an individual master site are propagated (sent) to all other
participating
 master sites.
There are two types of multimaster replication: asynchronous and
synchronous.
 Asynchronous replication, often referred to as store-and-forward
replication, captures any local changes, stores them in a queue, and, at
regular intervals, propagates and applies these changes at remote sites.
Synchronous replication, also known as real-time replication, applies any
changes or executes any replicated procedures at all sites participating in
the replication
 environment as part of a single transaction.

8. Materialized View Replication

9.  Oracle uses materialized views (also known as snapshots)
to replicate data to non-master sites in a replication
environment and to cache expensive queries in
 a data warehouse environment.
A materialized view is a replica of a target master from a
single point in time. The
 master can be either a master table at a master site or a
master materialized view at a materialized view site.
Materialized views helps to achieve one or more of the
following goals:
 ■ Ease Network Loads
 ■ Create a Mass Deployment Environment
 ■ Enable Data Sub-setting
 ■ Enable Disconnected Computing.

10. Multimaster and Materialized View
Hybrid Configurations

11.  Hybrid configurations can have any number of master sites and
multiple materialized view sites for each master.
 ■ Replicated master tables must contain data for the full table
being replicated,
 whereas materialized views can replicate subsets of master
table data.
 ■ Multimaster replication enables you to replicate changes for
each transaction as
 the changes occur. Materialized view refreshes are set oriented,
propagating
 changes from multiple transactions in a more efficient, batch-
oriented operation,
 but at less frequent intervals.
 ■ If conflicts occur because of changes made to multiple copies
of the same data,
 then detection and resolution of conflicts always occurs at a
master site or a master
 materialized view site.

12. END