Distributed Transactions across cloud databases.

Installation and migration
The capabilities for distributed database transactions are provided through updates to the .NET libraries System.Data.dll and System.Transactions.dll. The DLLs ensure that two-phase commit is used where necessary to ensure atomicity. To start developing applications using elastic database transactions, install .NET Framework 4.6.1 or a later version. When running on an earlier version of the .NET framework, transactions will fail to promote to a distributed transaction and an exception will be raised.

Both SQL Database and SQL Managed Instance support client-side development experiences in C# and .NET. A server-side experience (code written in stored procedures or server-side scripts) using Transact-SQL is available for SQL Managed Instance only.

A server-side distributed transactions using Transact-SQL are available only for Azure SQL Managed Instance. Distributed transaction can be executed only between Managed Instances that belong to the same Server trust group. In this scenario, Managed Instances need to use linked server to reference each other.