New Features for Administrators - Question 083

Examine the command:

ALTER DATABASE ADD SUPPLEMENTAL LOG DATA (PRIMARY KEY) COLUMNS;

What does the command accomplish?

A. Creates an additional copy of the database online redo log files

B. Stores the primary key column values of each row involved in a DML operation in the online redo log files

C. Stores the primary key column values of each row involved in a DML operation in the supplemental log files

D. Stores the old and new primary key column values of each row involved in a DML operation only when the primary key is modified in the online redo log files

Answer: B

Explanation:

Database supplemental logging allows you to specify logging of primary keys, unique indexes or both. With this enabled, whenever a DML is performed, the columns involved in the primary key or unique index are always logged even if they were not involved in the DML. This only takes effect for statements which have not yet been parsed. It also invalidates all DML cursors in the cursor cache and therefore has an effect on performance until the cache is repopulated.

Incorrect Answers

A: This statement does not create an additional copy of the database online redo log files

C: Database supplemental logging stores the primary key column values of each row involved in a DML operation in the regular, not supplemental, online redo log files.

D: It stores the primary key column values of each row involved in a DML operation in the online redo log files.

OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 100-110 Chapter 2: Availability Enhancements

Oracle 9i New Features, Robert Freeman, p. 68-72 Chapter 3: New Oracle9i Availability and Recoverability Features