In what scenario should I choose SQL Data Sync and why not Transactional Replication?

Hi @SebastianMarkov ,

Welcome to Microsoft Q&A forum and thanks for using Azure services.

As I understand from the question, you want to know the scenario when we can choose SQL Data Sync and how it is different from Transactional Replication.

SQL Data Sync can be used for the below use cases:

• Hybrid Data Synchronization: With Data Sync, you can keep data synchronized between your databases in SQL Server and Azure SQL Database to enable hybrid applications. This capability may appeal to customers who are considering moving to the cloud and would like to put some of their application in Azure.
• Distributed Applications: In many cases, it's beneficial to separate different workloads across different databases. For example, if you have a large production database, but you also need to run a reporting or analytics workload on this data, it's helpful to have a second database for this additional workload. This approach minimizes the performance impact on your production workload. You can use Data Sync to keep these two databases synchronized.
• Globally Distributed Applications: Many businesses span several regions and even several countries/regions. To minimize network latency, it's best to have your data in a region close to you. With Data Sync, you can easily keep databases in regions around the world synchronized.

Transactional Replication and SQL Data Sync comparison is given below:

Reference: compare-with-transactional-replication

Demonstration video for SQL Data Sync: SQL Data Sync | Demo of Data Sync with Hub and Member as Azure SQL Database | Data Synchronization

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