SQL Data Sync is a service built on Azure SQL Database that lets you synchronize the data you select bi-directionally across multiple SQL databases and SQL Server instances.

Data Sync is based around the concept of a Sync Group. A Sync Group is a group of databases that you want to synchronize.

  • A Sync Group has the following properties:
  • The Sync Schema describes which data is being synchronized.
  • The Sync Direction can be bi-directional or can flow in only one direction. That is, the Sync Direction can be Hub to Member or Member to Hub, or both.
  • The Sync Interval is how often synchronization occurs.
  • The Conflict Resolution Policy is a group level policy, which can be Hub wins or Member wins.

Data Sync uses a hub and spoke topology to synchronize data. You define one of the databases in the group as the Hub Database. The rest of the databases are member databases. Sync occurs only between the Hub and individual members.

  • The Hub Database must be an Azure SQL Database.
  • The member databases can be either SQL Databases, on-premises SQL Server databases, or SQL Server instances on Azure virtual machines.
  • The Sync Database contains the metadata and log for Data Sync. The Sync Database has to be an Azure SQL Database located in the same region as the Hub Database. The Sync Database is customer created and customer owned.

When to use Data Sync

Data Sync is useful in cases where data needs to be kept up to date across several Azure SQL Databases or SQL Server databases. Here are the main use cases for Data Sync:

  • Hybrid Data Synchronization: With Data Sync, you can keep data synchronized between your on-premises databases and Azure SQL Databases 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. 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.

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