Understanding DB2®: Learning Visually with Examples

11.3. DB2 Isolation Levels

DB2 provides four isolation levels to control locking behavior. From the lowest isolation level to the highest these are

• Uncommitted read

• Cursor stability

• Read stability

• Repeatable read

These isolation levels use different locking strategies, so you can choose the level of data protection depending on the application design.

11.3.1. Uncommitted Reads

An uncommitted read (UR) is the lowest isolation level but provides the highest concurrency to the database applications. When you configure an application to perform uncommitted reads, the application will not acquire any row lock to read data. However, a nonrestrictive table lock is required (see Section 11.5, DB2 Locking, for more information). Since no row locks are acquired, ...