Sync Data Across Multiple Databases

• It is a service built on Azure SQL Database that lets you synchronize the data you select bidirectionally 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 and 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 describes 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:

1. 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.
2. 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.
   • This approach minimizes the performance impact on your production workload.
3. 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.

When not to Use Data Sync

1. Disaster Recovery
   • Recommendation: Azure Geo-Redundant Backups.
2. Read Scale (Reporting)
   • Recommendation: **Read-only Replicas.**
3. ETL (OLTP to OLAP)
   • Recommendation: Azure Data Factory or **SQL Server Integration Services.**
4. Migration From On-Premises to Azure SQL Database
   • Recommendation: **Azure Database Migration Service.**

Set up Azure SQL Data Sync

Monitor Azure SQL Data Sync with Log Analytics

Best practices for Azure SQL Data Sync

Troubleshoot Azure SQL Data Sync