ptg 594 CHAPTER 19 Replication FIGURE 19.45 Specifying a join filter on the SalesOrderHeader table (limiting the sales rows that will be published by joining for the North East customers only). Join filtering allows you to limit the rows you will publish, via join criteria, to another table. Figure 19.45 shows a complex join that filters SalesOrderHeader rows that correspond to North East Territory customers only (that is, those with TerritoryID values of 1 or 2). Creating Subscriptions Now that you have installed and configured the distributor, enabled publishing, and created a publication, you can create subscriptions. Remember that two types of subscriptions can be created: push or pull. Pull subscriptions allow remote sites to subscribe to any publication that they are allowed to, but for this to work, you must be confident that the administrators at the other sites have properly configured the subscriptions at their sites. Push subscriptions are easier to create because all the subscription processes are performed and administered from the publication/distrib- utor point of view. This also makes using them the most common approach. For this example, we use the New Subscription Wizard to create a push subscription: 1. In SQL Server Management Studio, locate the Replication node under the publica- tion server (the DBARCH-LT2\SQL08DE01 named instance in this example) or the Replication node under the subscription server (the DBARCH-LT2\SQL08DE03 named instance in this example). You can create a push subscription from either (but we use the subscription server here). Open the Replication node, navigate to the Local Subscription branch, right-click, and choose the New Subscriptions option. As you can see in Figure 19.46, choosing this option launches the New Subscription Wizard, where you can create one or more subscriptions to a publication and specify where and when to run the agents that synchronize the subscription. Download from www.wowebook.com ptg 595 Setting Up Replication 19 FIGURE 19.46 Launching the New Subscription Wizard from SQL Server Management Studio. FIGURE 19.47 Identifying the publication from which to subscribe. 2. You first need to identify the publisher and publication from which you want to create one or more subscriptions. As you can see in Figure 19.47, we have specified the publisher (DBARCH-LT2\SQL08DE01) and the publication that has been created for the AdventureWorks2008 database. Download from www.wowebook.com ptg 596 CHAPTER 19 Replication FIGURE 19.48 Run all agents at the Distributor (push subscriptions). 3. When you are presented with the option of where the replication agents will be run for the subscription, choose the first option—having the agents run at the distributor. This makes it a push subscription, which is much easier to control and manage centrally than a pull subscription (as shown in Figure 19.48). 4. Next, the New Database dialog appears, asking you to identify the database target for the subscription and the physical database files for its allocation (assuming that you want to create this from scratch using this wizard process). Figure 19.49 shows this New Database dialog, with the target database named AdventureWorks2008ODS. Essentially, we have decided to create a subscription that will continuously flow data from the publisher to the subscriber for all tables in the publication. This continuous replication at the transactional level effectively creates a mirror image of the data for operational usage. That’s why we have used the suffix ODS, for Operational Data Store, for the new database. This is a typical industry usage of replication that takes all read-only access to OLTP data and offloads it to the ODS copy of the same data (which is as close to up-to-date as the last transaction that was replicated to it). 5. In the Subscribers screen, with the new entry for the target subscriber server (the DBARCH-LT2\SQL08DE03 named instance in this example), check the box for the target subscription server. Figure 19.50 shows this subscriber server and the subscrip- tion database target. 6. Specify the process account and connection options for the distribution agent (to connect to the subscription server). Typically, you choose the option to use a domain account or choose to impersonate the process account (shown in Figure 19.51). 7. Specify the synchronization schedule for each agent. You want the distribution agent to run continuously, but you also have the options to run on a schedule and on demand (as shown in Figure 19.51). Download from www.wowebook.com ptg 597 Setting Up Replication 19 FIGURE 19.49 The New Database dialog specifying the target database (AdventureWorks2008ODS). FIGURE 19.50 Specifying the subscription server target database. Download from www.wowebook.com ptg 598 CHAPTER 19 Replication FIGURE 19.51 Distribution Agent Security and Synchronization Schedule for the subscription (Run Continuously). 8. Specify the initialization of the subscription. You want the subscription to be initial- ized immediately, but, depending on the size of the database, this might be accom- plished manually with a database backup of the publication database. 9. On the next screen, which lists the New Subscription Wizard actions, choose to create the subscription and generate a script file with all the steps to create the subscription for use later. 10. On the next wizard dialog, identify the location of the script to be generated. As shown in Figure 19.52, you are presented with the final wizard summary screen. Click Finish to create your subscription, initialize the subscription database, and enjoy a full transactional replication implementation. After you click Finish, the create subscription process starts and goes through each step. Remember to check for errors or warnings if any errors occur. When this process completes, you wait for the agents to initialize the target database and start replication to the subscriber. If you have specified that the schema and data be created immediately, things start happening quickly. The distribution agent finishes the job. As you can see in Figure 19.53, the distribution agent applies the schemas to the subscriber (as viewed from the Replication Monitor’s Distributor to Subscriber History tab). The bulk copying of the data into the tables on the subscriber side follows accordingly. After this bulk copying is done, the initialization step is completed, and active replication begins. Download from www.wowebook.com ptg 599 Setting Up Replication 19 FIGURE 19.52 The New Subscription Wizard summary. FIGURE 19.53 Delivering schemas and data to the subscriber. Download from www.wowebook.com ptg 600 CHAPTER 19 Replication FIGURE 19.54 Transactions replicating to the subscriber (pushed). The complete replication buildup is finished, and you should be fully functional for repli- cating transactions to the subscriber. Figure 19.54 shows what the replication buildup looks like from the Replication Monitor as transactions flow through the replication topology. This screenshot shows the transac- tion counts and commands being delivered on the last leg in the journey (from the distributor to a subscriber). Figure 19.55 shows the full replication topology that was built (Publisher, Distributor and Subscriber). Your replication topology is now completely functional and will replicate flawlessly for as long as you require. Scripting Replication Earlier, it was strongly suggested that you generate SQL scripts for all that you do because going through wizards every time you have to configure replication is a difficult way to run a production environment. In the example in the preceding section, you always chose to generate these scripts as you built up the replication configuration. This was only half the scripts needed, however. You must also generate the breakdown scripts (that is, those that drop and remove replication components) to remove each component of the replica- tion topology in case you need to start from scratch or, as an example, rebuild a subscriber that is completely nonfunctional. As you can see in Figure 19.56, SQL Server Management Studio has a great feature that allows the complete generation of all aspects of replication topology (including disabling and removing replication). Download from www.wowebook.com ptg 601 Scripting Replication 19 FIGURE 19.55 Full replication topology that was built (Publisher, Distributor, Subscriber). FIGURE 19.56 A script-generation feature for all replication topology components. NOTE Remember that working from scripts minimizes the errors you make while supporting your data replication environments (especially at 3:00 a.m.). Download from www.wowebook.com ptg 602 CHAPTER 19 Replication The following example shows the SQL scripts needed to generate the part of the data repli- cation configuration you just built with the wizard: From distribution Server /****** Scripting replication configuration. Script Date: 6/30/2009 10:49:03 AM ******/ /****** Please Note: For security reasons, all password parameters were scripted with either NULL or an empty string. ******/ /****** Begin: Script to be run at Distributor ******/ /****** Installing the server as a Distributor. Script Date: 6/30/2009 10:49:03 AM ******/ use master exec sp_adddistributor @distributor = N’DBARCH-LT2\SQL08DE02’, @password = N’’ GO Adding the agent profiles Updating the agent profile defaults exec sp_MSupdate_agenttype_default @profile_id = 1 GO exec sp_MSupdate_agenttype_default @profile_id = 2 GO exec sp_MSupdate_agenttype_default @profile_id = 4 GO exec sp_MSupdate_agenttype_default @profile_id = 6 GO exec sp_MSupdate_agenttype_default @profile_id = 11 GO Adding the distribution databases use master exec sp_adddistributiondb @database = N’distribution’, @data_folder = N’C:\ Program Files\Microsoft SQL Server\MSSQL10.SQL08DE02\MSSQL\Data’, @data_file = N’distribution.MDF’, @data_file_size = 6, @log_folder = N’C:\Program Files\ Microsoft SQL Server\MSSQL10.SQL08DE02\MSSQL\Data’, @log_file = N’distribution.LDF’, @log_file_size = 3, @min_distretention = 0, @max_distretention = 72, @history_retention = 48, @security_mode = 1 GO Adding the distribution publishers exec sp_adddistpublisher @publisher = N’DBARCH-LT2\SQL08DE01’, @distribution_db = N’distribution’, @security_mode = 1, @working_directory = N’C:\Program Files\Microsoft SQL Server\MSSQL10.SQL08DE02\MSSQL\ReplData’, @trusted = N’false’, Download from www.wowebook.com ptg 603 Monitoring Replication 19 @thirdparty_flag = 0, @publisher_type = N’MSSQLSERVER’ GO /****** End: Script to be run at Distributor ******/ use master GO The complete set of buildup and breakdown scripts for the example used here are available on this book’s CD. They are labeled CreatingXXX.sql for the buildup scripts and RemoveXXX.sql for the breakdown scripts. Monitoring Replication After replication is up and running, it is important for you to monitor it and see how things are running. You can do this in several ways, including using SQL statements, SQL Server Management Studio, and Windows Performance Monitor. You are interested in the agent’s successes and failures, the speed at which replication is done, and the synchroniza- tion state of tables involved in replication. Other issues to watch for are the sizes of the distribution database, growth of the subscriber databases, and available space on the distri- bution server’s snapshot working directory. Replication Monitoring SQL Statements One way to look at the replication configuration and validate row counts, for example, is to use various replication stored procedures, including the following: . sp_helppublication—Information on the publication server . sp_helparticle—Article definition information . sp_helpdistributor—Distributor information . sp_helpsubscriberinfo—Subscriber server information . sp_helpsubscription—Subscription information These stored procedures are all extremely useful for verifying exactly how the replication configuration is really configured. If you execute these stored procedures (from the publi- cation database), you get a great documentation of your complete replication topology that can be included in run books or other system documentation. Here’s what you might do to see how the current replication configuration has been built out: use AdventureWorks2008 go exec sp_helppublication exec sp_helparticle @publication=’PUBLISH AdventureWorks2008 - Transactional’ exec sp_helpdistributor exec sp_helpsubscriberinfo exec sp_helpsubscription go Download from www.wowebook.com . Files Microsoft SQL Server MSSQL10 .SQL0 8DE02MSSQLData’, @data_file = N’distribution.MDF’, @data_file_size = 6, @log_folder = N’C:Program Files Microsoft SQL Server MSSQL10 .SQL0 8DE02MSSQLData’,. @publisher = N’DBARCH-LT2 SQL0 8DE01’, @distribution_db = N’distribution’, @security_mode = 1, @working_directory = N’C:Program Files Microsoft SQL Server MSSQL10 .SQL0 8DE02MSSQLReplData’, @trusted. Wizard to create a push subscription: 1. In SQL Server Management Studio, locate the Replication node under the publica- tion server (the DBARCH-LT2 SQL0 8DE01 named instance in this example) or