Understanding Transactions In SQL Server

Jeanne Combrinck explains the purpose and nature of transactions in SQL Server:

Distributed Transactions:
You can use Distributed transactions which specifies the start of a SQL distributed transaction managed by Microsoft Distributed Transaction Coordinator (MS DTC). This is only applicable to SQL Server and no Azure. Transaction-level snapshot isolation does not support distributed transactions.

Is a user-defined transaction name used to track the distributed transaction within MS DTC utilities. transaction_name must conform to the rules for identifiers and must be <= 32 characters.

Is the name of a user-defined variable containing a transaction name used to track the distributed transaction within MS DTC utilities. The variable must be declared with a char, varchar, nchar, or nvarchar data type.

Jeanne also includes the important comment that nested transactions don’t really work the way you’d expect them to.  I probably could have ended that last sentence early with, “don’t really work.”

Related Posts

The Problems With NOLOCK

Rob Farley demonstrates the downside of the READ UNCOMMITTED isolation level: I’m going to create a table and insert exactly 1 million rows. This particular table will be a clustered index, and will contain 1 million GUIDs. 1 2 CREATE TABLE dbo.demoNOLOCK (someguid uniqueidentifier NOT NULL PRIMARY KEY); INSERT dbo.demoNOLOCK (someguid) SELECT TOP (1000000) NEWID() […]

Read More

Benefits Of Explicit Transactions

Kendra Little talks about explicit transactions and when they’re useful for single-statement operations: If you do not enable implicit transactions, and you don’t start an explicit transaction, you are in the default “autocommit” mode. This mode means that individual statements are automatically committed or rolled back as whole units. You can’t end up in a […]

Read More


June 2018
« May Jul »