question

Raj More avatar image
Raj More asked

Isolation Levels

For reading dirty data you can set isolation levels at a Connection level using

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

Do any of these help with locking / blocking issues at a global level?

ALTER DATABASE MyDatabase
SET ALLOW_SNAPSHOT_ISOLATION ON

or

ALTER DATABASE MyDatabase
SET READ_COMMITTED_SNAPSHOT ON
t-sqltransactionlockingblockingisolation-level
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Tom Staab avatar image
Tom Staab answered

I added tags for transaction and isolation-level to your question. There are some good answers in some of the previous questions:

What is snapshot isolation?

Which row-versioning transaction isolation level do you use?

Transaction Types in SQL Server 2005

short answer: Yes, both help by reducing the need for locking but both also increase usage of tempdb.

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Tom Staab avatar image Tom Staab ♦ commented ·
Just to clarify, those options are not for dirty reads. They are used to avoid lock/block issues when dirty reads are unacceptable.
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Matt Whitfield avatar image Matt Whitfield ♦♦ commented ·
Good answer as usual, sir.
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