Unlocking Synonym Comparisons in SQL Compare: Spotting Hidden Differences

When using database comparison tools like Redgate SQL Compare, you might expect it to meticulously highlight every divergence between your database schemas. However, users sometimes encounter situations where seemingly obvious differences, particularly in synonyms, are overlooked. Imagine a scenario where you’ve diligently set up synonyms across different environments, perhaps pointing to Finance_Feature.dbo.MyTable in development and Finance.dbo.MyTable in production. You would naturally expect SQL Compare to flag this discrepancy, but you might be surprised to find no difference reported.

This article delves into why SQL Compare might miss these synonym variations and, more importantly, how to ensure these crucial distinctions are identified. Understanding this nuance is vital for maintaining database integrity across different stages of your software development lifecycle.

The Scenario: A Tale of Two Synonyms

Let’s illustrate this with a practical example. Consider a development environment where databases are feature-specific, such as Sales_Feature and Finance_Feature. Within Sales_Feature, you might create a synonym dbo.MyTable that points to an object in Finance_Feature, like so:

USE [SimpleTalk_1_Dev]
GO
CREATE SYNONYM dbo.MyTable FOR Compare1.dbo.MyTable
GO

This setup often works seamlessly in development. However, when transitioning to production, your database structure evolves. You might have consolidated databases named simply Sales and Finance. Consequently, the synonym intended for production needs to point to the Finance database.

USE [SimpleTalk_5_Prod]
GO
CREATE SYNONYM dbo.MyTable FOR Compare2.dbo.MyTable
GO

Now, if you were to compare these two databases using SQL Compare with its default settings, you might be puzzled to see no differences reported for these synonyms, as depicted below.

Despite the synonyms clearly pointing to different locations (Compare1.dbo.MyTable vs. Compare2.dbo.MyTable), SQL Compare, by default, overlooks this distinction. Why does this happen?

Unveiling the Solution: It’s All in the Options

The key lies in SQL Compare’s project options. By default, SQL Compare is configured to disregard database and server name variations in synonyms. This default behavior is predicated on the understanding that teams often deploy databases across different environments (development, QA, production), where server and database names are likely to diverge. The tool, in its default state, prioritizes identifying schema differences within the same logical database structure, rather than focusing on environment-specific naming conventions.

To unveil the hidden synonym differences, you need to adjust this setting. Within your SQL Compare project, navigate to “Edit project” and then to the “Options” tab. Scroll down, and you will find the option labeled “Ignore database and server name in synonyms,” which is checked by default.

Unchecking this box fundamentally changes how SQL Compare handles synonyms. With this option disabled, the tool will now meticulously compare the full definition of the synonym, including the database and server name.

Upon unchecking “Ignore database and server name in synonyms” and re-running the comparison, the difference becomes immediately apparent.

Now, SQL Compare accurately identifies the variation in synonym definitions, ensuring that you are aware of these environment-specific configurations. This adjustment is equally effective when dealing with different server instances, a common scenario in many deployment pipelines.

Beyond SQL Compare: A Consistent Behavior Across Redgate Tools

It’s important to note that this “Ignore database and server name in synonyms” option isn’t exclusive to SQL Compare. It’s a core setting within the SQL Compare engine, which powers a suite of Redgate products designed for database DevOps. Therefore, you’ll find this same option and behavior in tools like SQL Change Automation, SQL Source Control, Flyway Desktop, and other components within the Redgate Deploy ecosystem. If you encounter situations where synonym deployments seem to be overlooked, verifying this option should be your first step in troubleshooting.

For teams striving to implement database DevOps practices and seeking robust tools to manage database changes and deployments, exploring Redgate’s suite of tools is highly recommended. Consider downloading a trial to experience firsthand how these tools can streamline your database development lifecycle and enhance accuracy in deployments across diverse environments.

Download a trial and unlock the full potential of precise database comparisons and deployments.