Understanding SQL Server Change Tracking: A Guide for Dev

Greetings Dev! In the world of database management systems, one of the most important tasks is tracking changes made to the database. This is where SQL Server change tracking comes in. In this article, we will dive deep into the world of SQL Server change tracking, its benefits, and how to implement it effectively.

What is SQL Server Change Tracking?

SQL Server change tracking is a feature that allows you to keep track of changes made to your database. It captures changes to tables, which can then be used to synchronize data between databases, backup information, or diagnose issues that arise from unintended changes.

The change tracking process is automatic, lightweight, and continuous. It does not require a lot of resources or complex coding to enable. Once change tracking is enabled, it runs in the background and captures any changes made to the database, including new records, updated records, and deleted records.

Benefits of SQL Server Change Tracking

There are many benefits to using SQL Server change tracking. Some of the most notable benefits include:

Enabling SQL Server Change Tracking

Enabling SQL Server change tracking is a straightforward process. Before we go into each step, let us discuss the requirements.

Requirements

To enable SQL Server change tracking, you need the following:

• SQL Server 2008 or later
• Permissions to create tables and enable change tracking

Steps to Enable SQL Server Change Tracking

Follow these steps to enable SQL Server change tracking:

Step 1: Create a Database

The first step in enabling SQL Server change tracking is to create a database. You can do this through SQL Server Management Studio or using Transact-SQL.

Step 2: Enable Change Tracking

The next step is to enable change tracking on the desired tables. You can use the ALTER TABLE statement to enable change tracking. Here is the syntax:

ALTER TABLE table_nameENABLE CHANGE_TRACKINGWITH (TRACK_COLUMNS_UPDATED = ON);

The WITH clause is optional. It enables you to specify whether you want to track changes made to all columns or only selected columns. Here, we are setting it to ON to track changes made to all columns.

Step 3: Verify Change Tracking is Enabled

You can verify that change tracking is enabled on a table by using the following SQL statement:

SELECT name, is_track_columns_updated_on FROM sys.change_tracking_tables;

The is_track_columns_updated_on column should be set to 1, indicating that change tracking is enabled.

Working with SQL Server Change Tracking Data

SQL Server change tracking data is stored in the change tracking tables. These tables are system tables and cannot be modified. You can use the CHANGE_TRACKING_CURRENT_VERSION function to get the current version of the change tracking data.

Querying Change Tracking Data

Here is an example of how to query change tracking data in SQL Server:

SELECT CT.SYS_CHANGE_VERSION, C.DetailsFROM Customer AS CINNER JOIN CHANGETABLE(CHANGES Customer, @last_sync_version) AS CTON C.Id = CT.Id;

This query retrieves the change tracking data for the Customer table. The CHANGETABLE function is used to retrieve the changes made to the table since the last synchronization. The @last_sync_version parameter is used to specify the last version of the data that was synchronized.

FAQs about SQL Server Change Tracking

Q: What is the difference between change tracking and change data capture?

A: Change tracking and change data capture are similar in that they both capture changes made to a database. However, change data capture captures detailed information about changes, including the user who made the change, when the change was made, and the value before and after the change. Change tracking, on the other hand, only captures the version of the data and the type of change made.

Q: How do I disable change tracking?

A: To disable change tracking, use the ALTER TABLE statement with the DISABLE CHANGE_TRACKING option, like this:

ALTER TABLE table_nameDISABLE CHANGE_TRACKING;

Q: Can I use change tracking with replicated databases?

A: Yes, change tracking can be used with replicated databases. In fact, it is recommended that you use change tracking to identify the changes made to a database that is being replicated.

Q: How much overhead does change tracking add to the database?

A: Change tracking is a lightweight process and does not add a significant amount of overhead to the database. However, the amount of overhead will depend on the amount of data being changed and the frequency of the changes.

Q: Can I use change tracking with third-party applications?

A: Yes, change tracking can be used with third-party applications. However, you will need to ensure that the application can work with the change tracking data.

Q: Can I roll back changes made using change tracking?

A: No, change tracking only captures changes made to the database. It does not allow you to roll back changes.

Conclusion

In conclusion, SQL Server change tracking is a powerful feature that allows you to keep track of changes made to your database. It is easy to set up, lightweight, and can be used to improve backup and restore processes, synchronize data, and diagnose issues. By following the steps outlined in this article, you can enable change tracking on your database and begin taking advantage of its benefits.