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Part V: Enterprise Data Management
What’s New with Replication in SQL 2012?
There are two new features in SQL Server 2012 replication:■ (^) Supports up to 15,000 partitions
■ (^) Supports AlwaysOn publisher Failover Support
Replication Concepts
SQL Server replication uses a publish-subscriber mode that may include a separate distribu-
tion server. It enables you to copy or move data and database objects to another database.
Consistency is maintained by a synchronizing process executed by replication. There can
be three types of servers in a replication topology:■ (^) Publisher: The source server.
■ (^) Distributor: For transactional replication and peer-to-peer replication, the dis-
tributor is where the changes are stored until they are replicated to the destination
server. For merge replication, the distributor is merely a repository for replication
process history. Changes and historical information are stored in a database called
the distribution database.
■ (^) Subscriber: The destination server.
Types of Replication
SQL Server 2012 offers fi ve basic types of replication, each serving a different purpose:
■ (^) Snapshot replication: A point-in-time image of database objects (a snapshot) is
copied from the source server to the destination server. This image generation and
deployment can be scheduled at whatever interval makes sense for your require-
ments; however, it is best used when the majority of your data seldom changes, and
when it does, it changes at the same time.
■ (^) Transactional replication: Transactions occurring on the source server are asyn-
chronously captured and stored in a repository (called a distribution database) and
then applied, again asynchronously, on the destination server.
■ (^) Oracle publishing: This is a variant of transactional replication. Instead of SQL
Server being the source server, an Oracle server is the source server, and changes
are replicated from the Oracle server to SQL Server. This SQL Server can be the fi nal
destination for the Oracle server’s data, or it can act as a gateway, and changes can
be replicated downstream to other SQL Servers, or other RDBMs. Oracle publishing
is only available on SQL Server Enterprise Edition and above.
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