Advanced Oracle PL/SQL Programming with Packages

21.1. PLVlog: Logging Activity in PL/SQL Programs

The PLVlog (PL/Vision LOGging) package offers a powerful, generic logging mechanism for PL/SQL-based applications. The need to log activity arises in a number of different settings, including logging errors, tracing execution, and auditing activity. Rather than build this functionality over and over again, you can use PLVlog to handle many different circumstances.

The central features of PLVlog include:

• Writing of log information to one of several different repositories, including a database table, a PL/SQL table, or an operating system file (for PL/SQL Release 2.3 and above).

• Simultaneous, optional display of logged information.

• Toggle processing of log activity. You can decide to turn off logging at any time without having to change your own application code.

• High-level programs to manage the log. You can display contents of the log with a single program call, and transfer the log contents from a PL/SQL table to a database table.

• Automated rollback and savepoint activity. The package provides the ability to preserve database-logged information even if the surrounding transaction is rolled back.

The following sections show how to use each of the different elements of PLVlog.

21.1.1. Controlling the Log Action

PLVlog writes information to the log only when it is turned on. The package provides a standard PL/Vision toggle to control the action of the logging mechanism. The programs comprising this toggle are:

PROCEDURE turn_on; PROCEDURE ...