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.

Arguments:
transaction_name
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.

@tran_name_variable
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

New(ish) VLF Status: 4

Paul Randal points out a new VLF status which can appear if you’re using an Availability Group: At least since I started working on the SQL Server team (just after 7.0 shipped) and since then there have only been two VLF status codes: 0 = the VLF is not active (i.e. it can be (re)activated […]

Read More

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

Categories

June 2018
MTWTFSS
« May Jul »
 123
45678910
11121314151617
18192021222324
252627282930