Types of Replication
Microsoft® SQL Server™ 2000 provides the following types of replication that you can use in your distributed applications:
- Snapshot replication
- Transactional replication
- Merge replication
Each type provides different capabilities depending on your application, and different levels of ACID properties (atomicity, consistency, isolation, durability) of transactions and site autonomy. For example, merge replication allows users to work and update data autonomously, although ACID properties are not assured. Instead, when servers are reconnected, all sites in the replication topology converge to the same data values. Transactional replication maintains transactional consistency, but Subscriber sites are not as autonomous as they are in merge replication because Publishers and Subscribers generally should be connected continuously for updates to be propagated to Subscribers.
It is possible for the same application to use multiple replication types and options. Some of the data in the application may not require any updates at Subscribers, some sets of data may require updates infrequently, with updates made at only one or a few servers, while other sets of data may need to be updated daily at multiple servers.
Which type of replication you choose for your application depends on your requirements based on distributed data factors, whether or not data will need to be updated at the Subscriber, your replication environment, and the needs and requirements of the data that will be replicated. For more information, see Planning for Replication.
Each type of replication begins with generating and applying the snapshot at the Subscriber, so it is important to understand snapshot replication in addition to any other type of replication and options you choose.