SQL Server Change Tracking: 3 Easy Steps

Microsoft SQL Server provides organizations with a powerful yet simple database management tool to store their daily transactions and perform data analytics on the stored data. This tool operates on the Structured Query Language and is a popular name in the current IT market. Its flexibility, scalability, and business intelligence coupled with Microsoft’s security make it an all-in-one platform to manage data related to millions of business transactions in one go. 

Today, businesses are legally tasked with auditing data records, checking for suspicious and malicious activities, implementing forensic data auditing, tracking security violations and much more. Organizations turn to SQL Server Change Tracking for performing the above-mentioned activities and audit the changes in their data seamlessly. All the operations regarding insertion, update or deletion of data present in a table are captured periodically. The SQL Change Tracking feature scans the transaction logs to identify changes in data and record them for efficient auditing. This way, companies can rely on SQL Server’s lightweight mechanism to monitor and audit its incremental data changes.

This article will introduce you to SQL Server and discuss its key features. It will further elaborate on the importance of SQL Server Tracking and list the types of methods available to achieve data tracking with SQL. The article will also provide you with 3 easy steps to set up your SQL Tracking and Auditing functionalities. Read along to learn more about this tool and its limitations!

What is SQL Server?

Microsoft SQL Server provides robust facilities for data storage and retrieval in the form of a Relational Database Management System (RDBMS). This tool facilitates a rich collection of functionalities among which Transactional Processing, Data Auditing and Data Analytics are used widely by businesses today. Moreover, Microsoft SQL Server holds its position as one of the top 3 most popular database management platforms along with Oracle and IBM products.

Developers can rely on ANSI SQL, a standard Structured Query Language (SQL) to operate on Microsoft SQL Server which also has its own in-house SQL version, the Transact SQL (T-SQL). The T-SQL has unique exception handling features and supports you to perform various data operations. Furthermore, you can leverage the SQL Server Management Studio (SSMS) as the interface tool for the Microsoft SQL server and automate the most complex tasks to have a seamless experience.

Key Features of Microsoft SQL Server

The popular features of Microsoft SQL Server are as follows:

• Accelerated Data Recovery: Microsoft SQL Server contains a powerful recovery and rollback setup that activates automatically during server crashes. This recovery mechanism relies on Transaction Logs to perform full or partial rollbacks with minimum delay time.
• Advanced Encryption: Data security and privacy are the 2 most basic necessities of any DBMS. Microsoft, in 2016, installed AlwaysEncrypted software on its SQL Server to provide you with transparent encryption of column data. Furthermore, this feature performs encryption without presenting the Database Administrators with any access to the secret keys (Decryption).
• Intelligent Query Processing: Microsoft SQL Server offers great performance results using Dynamic Memory Grants, Table Variable Compilation, etc. This comes as a result of an in-built Query Optimizer that manages the execution plan.
• Advanced Analytics: You can access the Microsoft SQL Server data seamlessly and perform a detailed analysis to seek valuable insights. Furthermore, you can work with the Server Analysis Service (SSAS) of Microsoft which performs Data Mining tasks efficiently.

To learn more about Microsoft SQL Server, visit here.

Importance of SQL Server Change Tracking

Change Tracking refers to a mechanism that supports your applications to change the data present in the SQL Server database and access those modifications using queries. This lightweight solution, simplify the task of developers by allowing them to build custom queries which can integrate their various applications into the databases. 

SQL Server Change Tracking is a powerful tracking technique, in which the information related to database change is available as soon as the DML command commits. Moreover, unlike other methods such as Change Data Capture (CDC), etc. the Change Tracking mechanism does not face any delay issues. Creating such Change Tracking queries involve a lot of SQL understanding and frequently requires you to use some combination of triggers, new tables, timestamp columns, and custom cleanup processes. Depending on the type of your application, you may require different aspects of information about the database changes. 

Some of the popular question data regarding changes in data tables that applications can get answers for are as follows:

• Which rows have undergone transformations in a user table?: This question required only the name of rows that have undergone some changes. Since, it does not ask the number of times that row changed or what are the results of data modifications, simple queries under Data Tracking can provide the required results.
• What modifications have been done in a row?: This question requires the actual changes on a data table row. You can easily access the required information from the records that are generated and stored at the time of transactions. 

Types of SQL Server Change Audits

Microsoft SQL Server Change Tracking mechanism provides your applications with various techniques to audit the changes made to the Microsoft SQL database. Some of the most popular auditing techniques are: 

• Manual Auditing: This mechanism involves a set of queries and reports that allow you to track activities for each table, transaction, recent changes etc, manually. This method provides you with total control, however, it is time-consuming and you can not scale it to include all auditing events.
• SQL Server Triggers: SQL Server provides triggers as a basic functionality which has its own importance for users. These triggers are easy to set up and track database information. You can customize them according to your requirements and build your auditing information repositories. However, since triggers often throw errors to the client applications, you should not rely on them for SQL Server Data tracking in case of high throughput or bulk operations.
• SQL Server Extended Events: This SQL facility offers better performance than SQL Triggers and also provides you with built-in GUI tools. However, the Extended Events functionality can not help you with information regarding what data was inserted or deleted. Furthermore, it has no provision to compare the results of 2 auditings and get changes or updates.
• SQL Server Audit: This is an old SQL Server feature that provides you with a basic data aggregation facility while auditing. However, its usefulness in the modern data world is limited.
• Change Tracking:  This is an advanced feature of SQL Server and you will require training & experience to implement it. Moreover, it records only those changes that are connected with the primary key of a table.
• Change Data Capture (CDC): This is a relatively new feature in SQL Server and is much more useful than change tracking. Performing CDC will provide you with much better auditing capabilities as it tracks a variety of information regarding your data tables. However, CDC lacks a proper user interface and you need to rely on queries to use this comprehensive feature.

Steps to Set Up SQL Server Change Tracking as Audits

You can set up your SQL Server Change Tracking mechanism using the following 3 steps:

• Step 1: Enable SQL Server Change Tracking for your Database
• Step 2: Enable SQL Server Change Tracking for Every Table
• Step 3: Disabling SQL Change Tracking

Step 1: Enable SQL Server Change Tracking for your Database

You can enable SQL Server Change Tracking on your database table for auditing via ALTER DATABASE T-SQL statement, as shown below:

USE master
GO
ALTER DATABASE [CTAudit]
SET CHANGE_TRACKING = ON
(CHANGE_RETENTION = 2 DAYS, AUTO_CLEANUP = ON)

Write the above code in the Tracking tab (Database Properties) SQL Server Management Studio tool. The below image shows on-disk tables and the auto-clean process:

Step 2: Enable SQL Server Change Tracking for Every Table

Once you enable the SQL Server Tracking on a database, the next step is to do the same for each table so that you can track the DML changes. You can achieve this by using The Alter Table T-SQL statement as shown below:

USE CTAudit
GO
ALTER TABLE Employee_Main
ENABLE CHANGE_TRACKING
WITH (TRACK_COLUMNS_UPDATED = ON)

Keep in mind that the above code will not work on a database table if there is no Primary Key defined as shown below.

Once SQL Server Change Tracking is in place, your SQL Server Engine will generate an internal table, with the default name Change_Tracking_<Object_ID>. This will track the user table for changes due to the INSERT, UPDATE and DELETE statements.

Step 3: Disabling SQL Change Tracking

Enabling SQL Server Change Tracking on a database table will not prevent you from performing DDL changes at that table, except for the changes on the Primary Key that will fail unless the CT is disabled on that table.

Change Tracking can be disabled at the table level using the ALTER TABLE T-SQL statement below:

USE CTAudit
GO
ALTER TABLE Employee_Main
DISABLE CHANGE_TRACKING
GO

After disabling it at the table level, Change Tracking can be easily disabled at the database level, using the ALTER DATABASE T-SQL statement below:

USE master
go
ALTER DATABASE CTAudit
SET CHANGE_TRACKING = OFF
GO

Limitations of SQL Server Change Tracking

Microsoft SQL Server Change Tracking comes with its own share of limitations, some of which are as follows;

• The SQL Server Change Tracking features allow you to capture changes, however, a significant amount of coding is still required to capture the relevant changes.
• Enterprises seeking reliability and robustness for Change Tracking must also learn to manage the maintenance and data issues that come along with SQL Server Change Tracking features. Managing various new tables and different data types are some of the major concerns for enterprise developers.
• Every table needs to have a primary key if you wish to deploy SQL Server Change Tracking. This limits the usage of this feature and adds an extra constraint.

Conclusion

The article introduced you to SQL Server and explained its key features. It also explained the importance of SQL Server Change Tracking and discussed the types of techniques available for this purpose. Moreover, the article provided 3 easy steps to set up the required SQL Server mechanism for auditing and tracking data. It also listed the limitations associated what this mechanism. 

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