Azure SQL Data Sync has been ignored for quite some time, but has finally gotten an update (it’s in public preview). This release includes several major improvements to the service including new Azure portal support, PowerShell and REST API support, and enhancements to security and privacy.
SQL Azure Data Sync is a Microsoft Windows Azure web service that provides data synchronization capabilities for SQL databases. SQL Azure Data Sync allows data to be synchronized between on-premises SQL Server databases and Azure SQL databases; in addition, it can also keep multiple Azure SQL databases in sync (see Azure SQL Data Sync technical documentation).
SQL Data Sync targets the reference data replication scenario. Its key capabilities are:
Sync between SQL Server (2005 SP2 and later) and Azure SQL databases, or between Azure SQL databases:
- One-way and bi-directional sync
- One-to-one and hub-spoke
- Table filter and column filter
- Scheduled and on-demand
- Eventual consistency
Active Geo-Replication, in contrast, targets the GeoDR scenario for Azure SQL Database by replicating the database to another region. It only supports one-way replication (secondaries are read-only), replication is at database granularity, there is no database or column/row filter support, and it is only available for Premium service tier.
Comparing Data Sync to transactional replication: if you only need to do one way replication, both solution work. Transactional replication can provide better latency and transactional consistency. But it requires more complex setup and maintenance. It doesn’t require the latest SQL Server as publisher as SQL Server 2012 or later will work. Data sync is an Azure Database feature which requires less maintenance and is easier to setup. But it has a minimum five minute latency and a more significant performance impact to the source database (trigger based change tracking). It is optimized for bi direction sync.
Data Sync is now available in the new Azure portal. If you would like to try Data Sync refer to this tutorial. Existing users will be migrated to the new service starting June 1, 2017. For more information on migration look at the blog post “Migrating to Azure SQL Data Sync 2.0.”