SQL Server – Understanding of Replication

The primary purpose of replication is to distribute data from a master database to one or more secondary databases. Because Replication maintains a duplicate copy of data in synchronization with the master copy, the technology can be used to provide availability for application.

Type of Replication

• Snapshot
• Transactional
• Merge

Snapshot Replication

Snapshot Replication takes the entire set of data and sends it during the each cycle of replication. This is full copy of data that is sent by Publisher to subscriber.

Transactional Replication

Users obtain complete initial copies of the database and then obtain periodic updates as data changes.

We can configure transactional replication with two optional modes:

• Immediate updating subscriber
• Queued updating subscriber

Transactional Replication can be deployed in two alterative architectures:

• Bidirectional transactional replication
• Peer-to-peer transactional replication

Merge Replication

In merge replication received the data from two or more publishers is combined into a one subscriber.

Data Conflicts

Data conflicts can occurs within any environment that enable distributed processing of transaction.

Type of Conflicts

Three type of conflicts can occurs

• The insertion of a duplicate prinmary key on both publisher and subscriber
• A conflicting update same row at both publisher and subscriber
• An update of a nonexistent row

For more detail go to

http://msdn.microsoft.com/en-us/library/ms151198.aspx

http://msdn.microsoft.com/en-us/library/ms151215.aspx