- Configuring a Distributor
- Creating a Publication
- Creating Subscriptions
- Testing the Replication
- Summary
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Creating a Publication
Once you’ve configured a distributor, you’re ready to create publications. To invoke the publication wizard, right-click the local publications folder and choose New Publication from the pop-up menu. As with the Distribution Configuration Wizard, the first screen of this wizard is introductory in nature and can be skipped. The second screen allows you to choose the database in which you want to create a publication; for purposes of this article, I’ll create a publication within the AdventureWorksDW database that can be created as part of SQL Server 2005 installation. After selecting the database, you must choose the publication type. The wizard offers the following options:
- Snapshot Publication
- Transactional Publication
- Transactional Publication with Updatable Subscriptions
- Merge Publication
The wizard includes a brief description of each type of publication. I’ll use the transactional publication for this example; refer to my earlier articles for more info about other publication types.
A transactional publication can contain one or more articles. An article can be a table, a view (including indexed views), a user-defined function, or a stored procedure. For this example, I’ll replicate the dimAccount table from the AdventureWorksDW database. As shown in Figure 8, I can replicate all columns or a subset of all columns within a given table.
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Replication has certain rules as far as which columns can be filtered. Transactional replication prohibits filtering primary-key columns. In addition, if your publication allows updateable subscriptions, you must replicate the msrepl_tran_version column (added by SQL Server when you create such publications). Further, publications that allow updateable subscriptions must replicate any column that doesn’t allow nulls, doesn’t have a predefined default, and isn’t an identity column.
If you check the box Show Only Checked Objects in the List, the wizard limits the list of articles to only those that have been checked. The Article Properties button allows you to set properties for the highlighted article or for all table articles. As Figure 9 shows, you can set a multitude of replication-related properties for each article.
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Most properties you can set for table articles are self-explanatory; for example, the Copy Foreign Key Constraints option instructs the replication to include foreign key constraints when creating the table in the subscriber database.
A few properties deserve additional consideration:
- Destination Object Name, Destination Object Owner. The destination table isn’t required to have the same name or the same owner as the source object.
- Convert Data Types. This option automatically changes a user-defined data type to the base data type, because the user-defined data type might not exist on the subscriber(s).
- Convert TIMESTAMP to BINARY. When replicating a column with a TIMESTAMP data type, you can convert it to BINARY. The TIMESTAMP data type tracks the sequence of modifications; every time you change a data row, SQL Server will automatically change the value of the column with the TIMESTAMP data type. This is important because, if you’re not careful, you might end up with different values in the column with the TIMESTAMP data type on the publisher and the subscriber.
- Convert MAX Data Types to NTEXT and IMAGE. This option translates VARCHAR(MAX) and VARBINARY(MAX) data types, which are new in SQL Server 2005, to respective data types supported in previous versions.
- Convert XML to NTEXT. Translates the new XML data type to NTEXT.
- Another option that wasn’t available through wizards in previous versions of SQL Server is automatic identity range management. This option allows the database administrator to set the ranges of valid values for the identity column in the publisher and subscriber databases. For example, we could assign values 1,000,000 and greater to the publisher and 1 to 1,000,000 to the subscriber. When the publisher database reaches the upper limit for the identity range, it will automatically assign a new range so that publisher and subscriber identity values don’t overlap.
- The final group of options (not shown in Figure 9) determines how to replicate INSERT, UPDATE, and DELETE statements to the subscriber.
Once you’ve set the necessary properties for the article you want to replicate, you can add publication filters (see Figure 10). In previous versions of SQL Server, these filters were referred to as horizontal filters—you create them by supplying a WHERE clause to limit the number of published rows. As shown earlier, now you can filter the publication vertically by specifying which columns to publish.
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The next step is to create a snapshot and/or specify the snapshot agent’s schedule, as shown in Figure 11.
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The snapshot agent copies the schema and data of the replicated article(s) into the snapshot folder. If you click the Change button on this screen, you’ll get the typical dialog box for creating job schedules; you can run the snapshot agents monthly, weekly, daily, or even multiple times per day.
Next you specify the security settings for the snapshot and log reader agents (see Figure 12). I’ll discuss replication security in greater detail in a later article about transactional replication agents. For now, you just need to know that you can customize security for each agent or use different credentials for each.
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The wizard next offers you the option to script the commands for creating the publication. Review the synopsis of the steps the wizard is about to undertake; then specify the publication name and click Finish to create the publication.
Listing 2 shows the script for creating the publication.
Listing 2 Script for creating the example publication.
use [AdventureWorksDW] exec sp_replicationdboption @dbname = N’AdventureWorksDW’, @optname = N’publish’, @value = N’true’ GO -- Adding the transactional publication use [AdventureWorksDW] exec sp_addpublication @publication = N’DimAccount’, @description = N’Transactional publication of database ’’AdventureWorksDW’’ from Publisher ’’server\instance’’.’, @sync_method = N’concurrent’, @retention = 0, @allow_push = N’true’, @allow_pull = N’true’, @allow_anonymous = N’true’, @enabled_for_internet = N’false’, @snapshot_in_defaultfolder = N’true’, @compress_snapshot = N’false’, @ftp_port = 21, @ftp_login = N’anonymous’, @allow_subscription_copy = N’false’, @add_to_active_directory = N’false’, @repl_freq = N’continuous’, @status = N’active’, @independent_agent = N’true’, @immediate_sync = N’true’, @allow_sync_tran = N’false’, @autogen_sync_procs = N’false’, @allow_queued_tran = N’false’, @allow_dts = N’false’, @replicate_ddl = 1, @allow_initialize_from_backup = N’false’, @enabled_for_p2p = N’false’, @enabled_for_het_sub = N’false’ GO exec sp_addpublication_snapshot @publication = N’DimAccount’, @frequency_type = 4, @frequency_interval = 1, @frequency_relative_interval = 1, @frequency_recurrence_factor = 0, @frequency_subday = 8, @frequency_subday_interval = 1, @active_start_time_of_day = 0, @active_end_time_of_day = 235959, @active_start_date = 0, @active_end_date = 0, @job_login = null, @job_password = null, @publisher_security_mode = 1 use [AdventureWorksDW] exec sp_addarticle @publication = N’DimAccount’, @article = N’DimAccount’, @source_owner = N’dbo’, @source_object = N’DimAccount’, @type = N’logbased’, @description = null, @creation_script = null, @pre_creation_cmd = N’drop’, @schema_option = 0x000000000803509F, @identityrangemanagementoption = N’manual’, @destination_table = N’DimAccount’, @destination_owner = N’dbo’, @vertical_partition = N’false’, @ins_cmd = N’CALL sp_MSins_dboDimAccount’, @del_cmd = N’CALL sp_MSdel_dboDimAccount’, @upd_cmd = N’SCALL sp_MSupd_dboDimAccount’ GO
You can view the newly created publication’s properties by expanding the local publications folder, right-clicking the publication, and choosing Properties from the pop-up menu. The properties dialog box has several pages, each of which has a specific purpose:
- General. Shows the publication’s name, description, type, and the database on which the publication is based. You can modify subscription expiration options from this page.
- Articles. Lets you review the published articles, modify their properties, or add new articles to the publication.
- Filter Rows. Allows you to create horizontal filters for articles.
- Snapshot. Enables you to specify the snapshot folder location, snapshot format, or additional scripts to be executed before and after applying the snapshot.
- FTP Snapshot. Settings that let you allow subscribers to download the snapshot from an FTP share and configure FTP security.
- Agent Security. Controls security settings for the log reader and snapshot agents.
- Publication Access List. Specifies SQL Server and Windows logins who have permissions to create and synchronize subscriptions.
- Subscription Options. Provides a multitude of options for subscribers to the current publication.
The following table describes the subscription options you can set through the Publication Properties dialog box. Note that several of these options are new in SQL Server 2005.
|
Subscription Option |
New in SQL Server 2005 |
Description |
|
Independent Distribution Agent |
No |
Specifies whether to use an agent independent of other publications in the same database. |
|
Snapshot Always Available |
Yes |
Makes snapshot files always be available for initializing subscriptions. This option requires an independent distribution agent. |
|
Allow Anonymous Subscriptions |
No |
Supports anonymous subscriptions, typically used for replicating over the Internet. This option requires Snapshot Always Available. |
|
Attachable Subscription Database |
No |
Specifies whether subscriptions can be created by attaching the publication database on the subscriber. This option requires Snapshot Always Available. |
|
Allow Pull Subscriptions |
No |
Provides support for pull subscriptions. |
|
Allow Initialization from Backup Files |
Yes |
Enables subscriptions to be created by restoring the publication database backup on the subscriber. |
|
Allow Non-SQL Server Subscribers |
No |
Permits non-SQL Server subscribers. |
|
Allow Data Transformations |
No |
Allows for data to be transformed before it’s sent to subscribers. This option is deprecated. |
|
Replicate Schema Changes |
Yes |
Perhaps the most important change introduced with SQL Server 2005. If this option is set to YES (the default value), replication can deliver to the subscriber(s) any ALTER TABLE statements executed on publishers. In previous releases, some schema changes required removing articles from the publication and were therefore associated with downtime. |
|
Allow Peer-to-Peer Subscriptions |
Yes |
Determines whether subscribers can participate in peer-to-peer relationship with publishers. Peer-to-peer topology allows multiple nodes to act as publishers and subscribers at the same time. This is similar to bidirectional replication available in previous releases. |
|
Allow Immediate Updating Subscriptions |
No |
Controls whether data changes on subscriber(s) can be delivered immediately to the publisher. |
|
Allow Queued Updating Subscriptions |
No |
Specifies whether data changes on subscriber(s) can be queued and delivered to the publisher at a later time. This option is useful if the network line between the publisher and subscriber isn’t always reliable. |