ManagingReplication•Chapter9 407 Conflict tables are created to store conflict information. The conflict tables match the schema of the published tables: each published table is scripted, and then the script is used to create the conflict table in the publication database. Conflict tables are named in the form dbo.MSmerge_conflict_ <Publication>_<Article>. Components Merge replication uses two components, Snapshot Agent and Merge Agent. If the publication is unfiltered or uses static filters, the Snapshot Agent creates a single snapshot. If the publication uses parameterized filters, the Snapshot Agent creates a snapshot for each partition of data. The Merge Agent applies the initial snapshots to the Subscribers. It also merges incremental data changes that occurred at the Publisher or Subscribers after the initial snapshot was created, and detects and resolves any conflicts according to rules you configure. Replication Configuration Though there are several replication types, which we discussed earlier, configuration of those types are almost similar. Therefore, in this chapter we will look at how to configure Merge Replication. Later we will discuss how to configure Peer-to-Peer Replication. Configuration of Distributor Before configuring any replications on your server, you need to configure your distribution. If no distribution is available when configuring publication, the publication wizard will ask for relevant information to configure the distribution. EXERCISE 9.1 C o n f i g u r i n g Di s t r i b u t o r 1. Launch Open SQL Server Management Studio from Program Files| SQL Server 2008. 2. Supply the correct authentication for you to login to the SQL Server in which you are going to configure the distribution. 3. In the SQL Server Management Studio, navigate to Replication node in the Object Explorer. Right-click the Replication node and select Configure Distribution in the context menu. 408 Chapter9•ManagingReplication 4. After the start page you will be taken to the screen shown in Figure 9.2. From this screen, you can decide where your distribution server is. It can be either on the same database server instance where your publication is or on some other server that must already be configured as a distributor. Figure 9.2 Configuring Distributor Server 5. Configure the snapshot folder. To support both push and pull subscriptions, use a network path to refer to this folder. 6. Configure the distribution database. Supply the database name, database data file path and name, and database log file path and name. By default the database name is distribution. 7. Next you can add who can use this distributor when they become publishers. Configuration of Publisher After configuring distribution, the next step is to configure publisher, which is the major configuration in Replication. Exercise 9.2 will help you create a publisher. ManagingReplication•Chapter9 409 EXERCISE 9.2 Co n f i g u r i n g Pu b l i s h e r 1. Launch Open SQL Server Management Studio from Program Files| SQL Server 2008. 2. Supply the correct authentication for you to login to the SQL Server in which you are going to configure the publisher. 3. Navigate to Local Publication leaf under the Publication leaf and right-click the Local Publication leaf. Select New Publication…. 4. After the starting screen, the next screen asks you to select the database you want to publish. All the user databases will be listed, which means that you cannot replicate system databases. 5. After selecting the database, select the Replication type you want to implement, as seen in Figure 9.3. Figure 9.3 Selecting Publication Type 410 Chapter9•ManagingReplication Four replication types are shown and Peer-to-Peer Replication is missing here. We will see how we can configure Peer-to-Peer Replication later. When configuring replication, the most difficult part is to select which replication you want. Figure 9.3 gives you a short description about each replication so that you can be sure before selecting a replication type. In this example, we are going to configure Merge Replication, so we will select the last option. 6. Next, you will be asked what the database versions are for subscribers. This is Merge Replication specific configuration, and will not be seen for other replication configurations. In Figure 9.4, you can see that Merge Replication supports SQL Server versions after 2000. Figure 9.4 Subscriber Types Also, in SQL Server 2000, DDL replication is not supported. 7. Another important configuration is to configure Articles. As you can see in Figure 9.5, you have the luxury of replicating not only tables and views, but also stored procedures and user-defined functions as well. ManagingReplication•Chapter9 411 SQL Server requires that all tables referenced by published views and indexed views be available at the Subscriber. If the referenced tables are not published as articles in this publication, they must be created at the Subscriber manually. In case of transactional replication you are not allowed to select tables without primary keys to select as articles. 8. The next screen is an issue screen of the previous selected articles. For example, in the case of Merge Replication, tables without rowguid will be listed. Also, if you have selected views and have not selected referenced tables,which are referred by views again, a warning will be raised here. 9. The next screen lets you set filters (Figure 9.6). By clicking Add, you can set filters. You can create either static filters or dynamic filters. Static filters are straightforward; a simple where clause filters data. Dynamic filters filter which different subscribers receive different portions of data. For example, you may have Figure 9.5 Publisher Articles . Launch Open SQL Server Management Studio from Program Files| SQL Server 2008. 2. Supply the correct authentication for you to login to the SQL Server in which you are going to configure the distribution. 3 Launch Open SQL Server Management Studio from Program Files| SQL Server 2008. 2. Supply the correct authentication for you to login to the SQL Server in which you are going to configure the publisher. 3 conflict information. The conflict tables match the schema of the published tables: each published table is scripted, and then the script is used to create the conflict table in the publication