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Background documentation Isolation Level Locate the document in its SAP Library structure

The lock mode plays an important part in the lock behavior. The lock mode is determined by specifying an isolation level.

By defining an isolation level, you specify whether and how shared locks and exclusive locks are implicitly requested or released (Requesting and Releasing a Lock).

The selected isolation level affects both the degree of concurrency and the guaranteed consistency.

·        A high degree of concurrency is characterized by a state in which a maximum number of concurrent transactions can process a database without long waiting periods for locks to be released.

·        As far as consistency is concerned, phenomena can arise through concurrent access to the same database at different isolation levels.

The lower the value of the isolation level, the higher the degree of concurrency and the lower the guaranteed consistency. This means that a compromise between concurrency and consistency that best suits the requirements of the application at hand must always be found.

You can use the CONNECT statement to help define the isolation level you require. The following isolation levels exist:

Isolation Level 0 (uncommitted)

Isolation Level 1 or 10 (committed)

Isolation Level 15

Isolation Level 2 or 20 (repeatable)

Isolation Level 3 or 30 (serializable)

 

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