What's the difference between peer-to-peer and merge replication with SQL Server?

Question

What's the difference between peer-to-peer replication and merge replication using SQL Server?

Answer 1

EDIT Peer to Peer replicaiton is of two types - Transactional and Snapshot. Both of these are one way - from publisher to subscriber.

Transactional and Snapshot replication move data from publisher to subscriber. They are used primarily for editing in a single place and viewing / reporting data in multiple places. Transactional is almost instantaneous, while snapshot has to be scheduled. Transactional has a heavy initial resource requirement because it creates an initial snapshot and then it reads subsequent transactions from the transaction log to send data over. Snapshot is resource intensive every time it runs because it generates a new snapshot every time.

Merge replication lets you have multiple places where you can edit the data, and have it synchronized in near-real-time with the peers. Merge replications essentially runs a transactional replication engine to distribute the transactions, and additional logic to apply the transactions at the destination(s).

Here is some reading material http://technet.microsoft.com/en-us/library/ms152531.aspx

Answer 2

1. Peer-to-Peer Transactional Replication is used to support applications that distribute read operations across a number of server nodes.

   Although read operations can be spread across multiple nodes, write operations are applied to a single node and propogated out to the other nodes. The application needs to be aware of the network topology in order to direct your write activity.

   Peer-To-Peer Replicaiton

2. Merge Replication is bi-directional i.e. read and wrtie operations are propogated to and from all nodes. Merge replication often requires the implementation of conflict resolution.

   See: How Merge Replication Works