Programming Replication Using System Stored Procedures
In SQL Server, programmatic access to all of the user-configurable functionality in a replication topology is provided by system stored procedures. While stored procedures may be executed individually using the SQL Server Management Studio or the sqlcmd command-line utility, it may be beneficial to write Transact-SQL script files that can be executed to perform a logical sequence of replication tasks.
Scripting replication tasks provides the following benefits:
- Keeps a permanent copy of the steps used to deploy your replication topology.
- Uses a single script to configure multiple Subscribers.
- Quickly educates new database administrators by enabling them to evaluate, understand, change, or troubleshoot the code.
Security Note: Scripts can be the source of security vulnerabilities; they can invoke system functions without user knowledge or intervention and may contain security credentials in plain text. Review scripts for security issues before you use them.
Creating Replication Scripts
From the standpoint of replication, a script is a series of one or more Transact-SQL statements where each statement executes a replication stored procedure. Scripts are text files, often with a .sql file extension, that can be run using the sqlcmd utility. When a script file is run, the utility executes the SQL statements stored in the file. Similarly, a script can be stored as a query object in a SQL Server Management Studio project.
Replication scripts can be created in the following ways:
- Manually create the script.
- Use the script generation features that are provided in the replication wizards or
- SQL Server Management Studio. For more information, see How to: Script Replication Objects (SQL Server Management Studio).
- Use Replication Management Objects (RMOs) to programmatically generate the script to create an RMO object.
When you manually create replication scripts, keep the following considerations in mind:
- Transact-SQL scripts have one or more batches. The GO command signals the end of a batch. If a Transact-SQL script does not have any GO commands, it is executed as a single batch.
- When executing multiple replication stored procedures in a single batch, after the first procedure, all subsequent procedures in the batch must be preceded by the EXECUTE keyword.
- All stored procedures in a batch must compile before a batch will execute. However, once the batch has been compiled, and an execution plan has been created, a run-time error may or may not occur.
- When creating scripts to configure replication, you should use Windows Authentication to avoid storing security credentials in the script file. If you must store credentials in a script file, you must secure the file to prevent unauthorized access.
Sample Replication Script
The following script can be executed to setup publishing and distribution on a server.
-- This script uses sqlcmd scripting variables. They are in the form -- $(MyVariable). For information about how to use scripting variables -- on the command line and in SQL Server Management Studio, see the -- "Executing Replication Scripts" section in the topic -- "Programming Replication Using System Stored Procedures". -- Install the Distributor and the distribution database. DECLARE @distributor AS sysname; DECLARE @distributionDB AS sysname; DECLARE @publisher AS sysname; DECLARE @directory AS nvarchar(500); DECLARE @publicationDB AS sysname; -- Specify the Distributor name. SET @distributor = $(DistPubServer); -- Specify the distribution database. SET @distributionDB = N'distribution'; -- Specify the Publisher name. SET @publisher = $(DistPubServer); -- Specify the replication working directory. SET @directory = N'\\' + $(DistPubServer) + '\repldata'; -- Specify the publication database. SET @publicationDB = N'AdventureWorks'; -- Install the server MYDISTPUB as a Distributor using the defaults, -- including autogenerating the distributor password. USE master EXEC sp_adddistributor @distributor = @distributor; -- Create a new distribution database using the defaults, including -- using Windows Authentication. USE master EXEC sp_adddistributiondb @database = @distributionDB, @security_mode = 1; GO -- Create a Publisher and enable AdventureWorks for replication. -- Add MYDISTPUB as a publisher with MYDISTPUB as a local distributor -- and use Windows Authentication. DECLARE @distributionDB AS sysname; DECLARE @publisher AS sysname; -- Specify the distribution database. SET @distributionDB = N'distribution'; -- Specify the Publisher name. SET @publisher = $(DistPubServer); USE [distribution] EXEC sp_adddistpublisher @publisher=@publisher, @distribution_db=@distributionDB, @security_mode = 1; GO
This script can then be saved locally as
instdistpub.sql so that it can be run or rerun when needed.
The previous script includes sqlcmd scripting variables, which are used in many of the replication code samples in SQL Server Books Online. Scripting variables are defined by using
$(MyVariable) syntax. Values for variables can be passed to a script at the command line or in SQL Server Management Studio. For more information, see the next section in this topic, "Executing Replication Scripts."
Executing Replication Scripts
Once created, a replication script can be executed in one of the following ways:
Creating a SQL Query File in SQL Server Management Studio
A replication Transact-SQL script file can be created as a SQL Query file in a SQL Server Management Studio project. After the script is written, a connection can be made to the database for this query file and the script can be executed. For more information about how to create Transact-SQL scripts by using SQL Server Management Studio, see Writing, Analyzing, and Editing Scripts with SQL Server Management Studio.
To use a script that includes scripting variables, SQL Server Management Studio must be running in sqlcmd mode. In sqlcmd mode, the Query Editor accepts additional syntax specific to sqlcmd, such as
:setvar, which is used to a value for a variable. For more information about sqlcmd mode, see Editing SQLCMD Scripts with Query Editor. In the following script,
:setvar is used to provide a value for the
:setvar DistPubServer N'MyPublisherAndDistributor'; -- Install the Distributor and the distribution database. DECLARE @distributor AS sysname; DECLARE @distributionDB AS sysname; DECLARE @publisher AS sysname; DECLARE @directory AS nvarchar(500); DECLARE @publicationDB AS sysname; -- Specify the Distributor name. SET @distributor = $(DistPubServer); -- Specify the distribution database. SET @distributionDB = N'distribution'; -- Specify the Publisher name. SET @publisher = $(DistPubServer); -- -- Additional code goes here --
Using the sqlcmd Utility from the Command Line
The following example shows how the command line is used to execute the
instdistpub.sql script file using the sqlcmd utility:
sqlcmd.exe -E -S sqlserverinstance -i C:\instdistpub.sql -o C:\output.log -v DistPubServer="N'MyDistributorAndPublisher'"
In this example, the
-E switch indicates that Windows Authentication is used when connecting to SQL Server. When using Windows Authentication, there is no need to store a username and password in the script file. The name and path of the script file is specified by the
-i switch and the name of the output file is specified by the
-o switch (output from SQL Server is written to this file instead of the console when this switch is used). The
sqlcmd utility enables you to pass scripting variables to a Transact-SQL script at runtime using the
-v switch. In this example,
sqlcmd replaces every instance of
$(DistPubServer) in the script with the value
N'MyDistributorAndPublisher' before execution.
-X switch disables scripting variables.
Automating Tasks in a Batch File
By using a batch file, replication administration tasks, replication synchronization tasks, and other tasks can be automated in the same batch file. The following batch file uses the sqlcmd utility to drop and recreate the subscription database and add a merge pull subscription. Then the file invokes the merge agent to synchronize the new subscription:
REM ----------------------Script to synchronize merge subscription ---------------------- REM -- Creates subscription database and REM -- synchronizes the subscription to MergeSalesPerson. REM -- Current computer acts as both Publisher and Subscriber. REM ------------------------------------------------------------------------------------- SET Publisher=%computername% SET Subscriber=%computername% SET PubDb=AdventureWorks SET SubDb=AdventureWorksReplica SET PubName=AdvWorksSalesOrdersMerge REM -- Drop and recreate the subscription database at the Subscriber sqlcmd /S%Subscriber% /E /Q"USE master IF EXISTS (SELECT * FROM sysdatabases WHERE name='%SubDb%' ) DROP DATABASE %SubDb%" sqlcmd /S%Subscriber% /E /Q"USE master CREATE DATABASE %SubDb%" REM -- Add a pull subscription at the Subscriber sqlcmd /S%Subscriber% /E /Q"USE %SubDb% EXEC sp_addmergepullsubscription @publisher = %Publisher%, @publication = %PubName%, @publisher_db = %PubDb%" sqlcmd /S%Subscriber% /E /Q"USE %SubDb% EXEC sp_addmergepullsubscription_agent @publisher = %Publisher%, @publisher_db = %PubDb%, @publication = %PubName%, @subscriber = %Subscriber%, @subscriber_db = %SubDb%, @distributor = %Publisher%" REM -- This batch file starts the merge agent at the Subscriber to REM -- synchronize a pull subscription to a merge publication. REM -- The following must be supplied on one line. "\Program Files\Microsoft SQL Server\90\COM\REPLMERG.EXE" -Publisher %Publisher% -Subscriber %Subscriber% -Distributor %Publisher% -PublisherDB %PubDb% -SubscriberDB %SubDb% -Publication %PubName% -PublisherSecurityMode 1 -OutputVerboseLevel 1 -Output -SubscriberSecurityMode 1 -SubscriptionType 1 -DistributorSecurityMode 1 -Validate 3
Scripting Common Replication Tasks
The following are some of the most common replication tasks can be scripted using system stored procedures:
- Configuring publishing and distribution
- Modifying Publisher and Distributor properties
- Disabling publishing and distribution
- Creating publications and defining articles
- Deleting publications and articles
- Creating a pull subscription
- Modifying a pull subscription
- Deleting a pull subscription
- Creating a push subscription
- Modifying a push subscription
- Deleting a push subscription
- Synchronizing a pull subscription
17 July 2006