Advanced Oracle PL/SQL Programming with Packages

20.2. PLVrb: Performing Rollbacks

The PLVrb PL/Vision RollBack package provides a programmatic interface to rollback activity in PL/SQL. With PLVrb, you no longer issue explicit ROLLBACK and SAVEPOINT commands. Instead, you call the appropriate PLVrb module. This layer of code gives you the ability to change transaction-level behavior at runtime. With PLVrb, you can even execute soft-coded savepoints, a feat usually considered impossible in PL/SQL.

These different elements of the PLVrb package are explained in the following sections.

20.2.1. Controlling Rollbacks

One of the big advantages to using PLVrb instead of direct calls to ROLLBACK is that you have placed a layer of code between your application and the ROLLBACK. This layer gives you (through PL/Vision) the ability to modify rollback processing behavior without changing your application code. This is very important because it allows you to stabilize your code, but still change the way it works for purposes of testing and debugging.

PLVrb offers a standard PL/Vision toggle to control rollback processing. This triumvirate of programs is:

PROCEDURE turn_on;
PROCEDURE turn_off;
FUNCTION rolling_back RETURN BOOLEAN;

All that the first two procedures do is set the value of a private Boolean variable, but by correctly applying that Boolean inside an IF statement in PLVrb, the package's user gets to fine-tune the package's behavior.

20.2.2. Logging Rollbacks

The rollback action in an application is a critical step. It is, ...