Transactional Replication with Updatable Subscriptions

It is similar to the Transactional Replication that works with every transaction. It has some extra features. Here, both Publisher and Subscribers can update the existing data. It uses MSDTC to maintain the changes. It is so fast and its latency is low. This article explains how to configure Transactional Replication with Updatable Subscriptions in SQL Server 2008 R2?

Before start we need to learn some prerequisite knowledge about SQL server replication and transactional replication with updatable subscriptions. Some key points of transactional replication with updatable subscriptions are given bellow:

• Primary key is mandatory for every table.
• It is mandatory to active and running MSDTC.
• Need to create a link server for every subscriber to publisher.
• An auto generated unique identifier column is added to subscribers table.

Configuration of Transactional Replication with Updatable Subscriptions
To configure transactional replication with updatable subscriptions three steps are required:

1. Configuring Distribution
2. Creating Publisher
3. Creating Subscriber

Configuring Distribution
At first we need to configure a distributor database which manages the total replication process.

Creating Publisher
The steps to create publisher are given bellow:

Step1:
Connect to the server with actual server name.

Step2:
Expand the Replication folder and right click on Local Publications. Select New Publication.

Step3:
New Publication Wizard window will be open. Click next

Step4:
Select the database that contains database objects for publications. For example select “TestDB” and click next.

Step5:
Choose the appropriate publication type according to requirements. For now select Transactional publication with updatable subscriptions.

Step6:
Select the tables or others object to publish. We can select tables, stored procedures, views, and functions according to our choice. Here we will select only tables. Click next.
Remember that Primary key columns are mandatory for all tables in transactional replications. We can’t select tables which does not have a primary key column. If we try to select, it will provides warning message.

Step7:
A unique identifier column will be added to all the tables of publisher. It is used to track the changes. It is recommended and don’t delete this column from the table. Unless replication will not works.

Step8:
We can set filters to exclude unwanted rows. If required please add. Otherwise click next.

Step9:
Specify the time when Snapshot Agent will run. Select “Create a snapshot immediately and keep the snapshot available to initialize subscriptions” and click next.
Also we can select a schedule to run the snapshot agent. We can modify it any time from the jobs.

Step10:
Need to provide agent security. Specify the account under which the agent will run. Click Security Settings tab.

Stept11:
Under the Queue Reader Agent section, Click Security Settings tab.

Stept12:
Select “Run under the SQL Server Agent service account”. Click Ok.

Stept13:
Set the domain/machine account under which the snapshot agent process will run.
Select “Run under the SQL Server Agent service account”
Select “Using the following SQL Server login” and provides the credentials.
Click Ok.

Step14:
Click next.

Step15:
Click next.

Step16:
Give a suitable name to the publisher and click finish.

Step17:
If every thing is ok publication creation will be completed.

Creating Subscriber
After the creation of publisher the next step is to create the subscriber for it. The steps to create subscriber are given bellow:

Step1:
Right click on created publisher and select New Subscriptions.

Step2:
New Subscription Wizard window will be open. Click next

Step3:
Click next.

Step4:
Choose distribution agent location. Select the first one and click next.

Step5:
Choose subscribers and specify each subscriptions database. We can use same or remote SQL server as subscriber. We can set multiple subscribers for one publisher. In the subscriber list the default server is local. If we want to use different server, we need to click Add Subscriber and provides the credentials. Remember that for connection, the actual server name is mandatory. We need to create subscriber database. We can do that either restoring the publisher database or create new database. If we restore the database, then the database name will appear in the dropdown. Here we will use remote server (SDEV). After that, click next.

Step6:
Provide the process account and connection options for each distribution agent. Click the button highlighted in the bellow image.

Step7:
Provide distribution agent security. Specify the domain/machine account under which distribution agent will run.
Select “Run under the SQL Server Agent service account”
Provides the credential of SQL server
Click ok

Step8:
Click next.

Step9:
Specify synchronization agent schedule as Run continuously and click next.

Step10:
Specify initialize subscriptions “Simultaneously commit changes” and click next.

Step11:
Specify the login that will be used to connect to the Publisher when the replicated data is change. That mean need to create a link server for the Publisher. We can create a link server before or we can create it now.
In order to create new link server select “Create a linked server that connects using SQL Server Authentication” and provides the credentials.
For existing link server select “Use as linked server or remote server that you have already defined”
Click next.

Step12:
Choose “Create the subscription” and click next.

Step13:
Click finish. If everything is ok subscription creation will be completed. Expand local publications node and subscriber will be displayed. If we log on to subscriber database we will find the publisher.

In this way we can create transactional replication with updatable subscriptions in SQL Server 2008 R2.