New Isolation Levels Available in SQL Server 2005

http://www.sql-server-performance.com/articles/per/new_isolation_levels_p1.aspx



In SQL Server 2005, two new isolation levels are introduced, both of which use row versioning. They include:

READ_COMMITTED_SNAPSHOT (statement level)
ALLOW_SNAPSHOT_ISOLATION (transaction level)

'READ_COMMITTED_SNAPSHOT' isolation level is especially useful for applications that you migrate from platforms that support obtaining
earlier consistent versions of data, such as when an application migrates from Oracle to SQL Server.


SQL Server 2005 Row Versioning-Based Transaction Isolation
http://msdn.microsoft.com/en-us/library/ms345124(SQL.90).aspx

Understanding Row Versioning-Based Isolation Levels
http://msdn.microsoft.com/en-us/library/ms189050.aspx

Row Versioning Resource Usage
http://msdn.microsoft.com/en-us/library/ms175492.aspx


Performance Counter: Transaction
Version Store Size (KB).
Version Generation rate (KB/s).
Version Cleanup rate (KB/s).
Version Store unit count.
Version Store unit creation.
Version Store unit truncation.
Update conflict ratio.
Longest Transaction Running Time.
Snapshot Transactions.
Transactions.