O'Reilly logo

Guru's Guide to SQL Server Architecture and Internals, The by Ken Henderson

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Transaction Isolation Levels

SQL Server supports four TILs. As mentioned earlier, a transaction's isolation level controls how it impacts and is impacted by other transactions. The trade-off is always one of data consistency versus concurrency. Selecting a more restrictive TIL increases data consistency at the expense of accessibility. Selecting a less restrictive TIL increases concurrency at the expense of data consistency. The trick is to balance these opposing interests so that the needs of your application are met.

Use the SET TRANSACTION ISOLATION LEVEL command to set a transaction's isolation level. Valid TILs include READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ, and SERIALIZABLE.

READ UNCOMMITTED

Specifying READ UNCOMMITTED is essentially ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required