Transactional Replication in SQL Server

Transactional Replication works with every transaction. When any changes made at the Publisher end, it’s delivered it to the Subscriber almost in the real time. Except first snapshot, it only transfers the changes or updates. That’s why its latency is very low and it is faster. This article explains how to configure Transactional Replication in SQL Server 2008 R2?

Before start we need to learn some prerequisite knowledge about SQL server replication and transactional replication. Some key point of transactional replications are given bellow:

• Must need one Primary key column for every table.
• Subscriptions are read only.
• Modifications are adjusted on a transaction basis.

Configuration of Transactional Replication
To configure transactional replication 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.

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

Step8:
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.

Step9:
Need to provide agent security. Specify the account under which the agent will run. Click Security Settings tab.

Stept10:
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.

Step11
Click next.

Step12
Click next.

Step13
Give a suitable name to the publisher and click finish.

Step14:
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 “Immediately” and click next.

Step11:
Choose “Create the subscription” and click next.

Step12
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 in SQL Server 2008 R2.