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What is DTC in database?
A distributed transaction spans two or more databases. As the transaction manager, DTC coordinates the transaction between SQL Server instances, and other data sources. Each instance of the SQL Server database engine can operate as a resource manager.
What is SQL DTC?
MSDTC (aka Microsoft Distributed Transaction Control) is a piece of software that a lot of people use, but they don’t really know what it does, or how it works. MSDTC is used by SQL Server and other applications when they want to make a distributed transaction between more than one machine.
What is DTC role?
Review the status of a specified travel authorization. Review the status of financial accounting for a specified trip. Review and approve final settlements prior to forwarding to DADS. Digitally sign travel authorizations and vouchers.
How to create DTC service for always on availability group?
A sample script can be seen at Create Clustered DTC for an Always On Availability Group. Enable network access securely for the clustered DTC resource. Stop and disable local DTC service. Cycle the SQL Server service for each instance in the Availability Group.
When to use local DTC in SQL Server always on?
You can also notice that we use a Local DTC instead of a clustered DTC for SQL Server Always On Availability Group. If you right-click on the UOW, you get an option to Commit, Abort or Forget this DTC transaction. We do not want manual intervention here so let’s ignore it as of now.
Is there DTC support in SQL Server 2017?
In the generated script for the availability group configuration, it adds a new argument DTC_SUPPORT=PER_DB to highlight distributed transactions DTC support. Before SQL Server 2017, SQL Server did not use DTC for cross distributed transactions in different databases of an instance unless explicitly configured.
How does DTC mark a distributed transaction as in doubt?
As the transaction was not finished (commit or rollback) before AG failover, DTC marks it as an in-doubt distributed transaction. On the new replica, it tries to recover the in-doubt distributed transaction 1 transactions rolled back in database ‘Distribute2’ (10:0).