Skip to main content
pdf?stylesheet=default
Blackboard Help

READ COMMITTED SNAPSHOT Isolation Level

If you are a Managed Hosting customer, this topic doesn't apply to you.
 

The READ_COMMITTED_SNAPSHOT database option determines "what locks SQL Server takes when accessing data and, therefore, by extension, they determine the level of concurrency and consistency that statements and transactions experience." Quotation taken from Craig Freedman's SQL Server Blog: "Read Committed Isolation Level" . To learn more about the option, see http://msdn.microsoft.com/en-us/library/ms173763.aspx.

READ_COMMITTED_SNAPSHOT specifies that data read by any statement in a transaction will be the transactionally consistent version of the data that existed at the start of the transaction. The transaction can recognize only those data modifications that were committed before the start of the transaction. Data modifications made by other transactions after the start of the current transaction are not visible to statements executing in the current transaction. The effect is that the statements in a transaction get a snapshot of the committed data as it existed at the start of the transaction.

Blackboard recommends setting READ_COMMITTED_SNAPSHOT to ON for the BBLEARN (legacy: BB_BB60) schema:

ALTER DATABASE BBLEARN
SET READ_COMMITTED_SNAPSHOT ON
GO

To disable READ_COMMITTED_SNAPSHOT, change the value to OFF:

ALTER DATABASE BBLEARN
SET READ_COMMITTED_SNAPSHOT OFF
GO